学习java的日子 Day64 学生管理系统 web2.0 web版本

MVC设计模式

概念 - 代码的分层

MVC：项目分层的思想

字母	表示	层	理解
M	Modle	模型层	业务的具体实现
V	View	视图层	展示数据
C	Controller	控制器层	控制业务流程（跳转）

1.细化理解层数

Controller：控制器层，用于存放Servlet（页面跳转）

View：视图层，用于存放前端页面（jsp）

Modle-Biz/service：逻辑业务层，用于存放业务具体的实现

Modle-Dao/mapper：数据持久层，用于存放操作数据的实现（数据的增删改查）

在这里插入图片描述

MVC涉及到了前端，而后端只涉及到了MC

1.1 优缺点

缺点：使用MVC不能减少代码量，还会增加系统结构和实现的复杂性

优点：整个项目结构清晰，业务逻辑清晰，降低了代码的耦合性，代码的重用性高

注意：一般来说，使用设计模式都会增加代码量

1.2 各层的命名规范

Controller控制器层：controller/servlet/action/web

Modle-Biz 逻辑业务层：service/biz

Modle-Dao 数据持久层：dao/persist/mapper

2.学生管理系统 web2.0 mvc版本

具体的业务逻辑详情请见 Day59 学生管理系统 web1.0（直接使用servlet+jsp写的），v2.0只是使用mvc分层思想进行构造

项目结构：(总结里有展示所有层)

注意：mapper层、service层、controller层

在这里插入图片描述

2.1 学生 student

StudentMapper

通过具体的业务，判断需要用到什么增删查改，然后写数据库增删查改的接口，让实现类去实现

public interface StudentMapper {

    //添加学生
    public void add(String username,String password,String name,String sex,int age,String hobbies,String photo);

    //删除学生，通过username
    public void delete(String username);

    //更新学生的密码，通过username和newPassword
    public void update(String username,String newPassword);

    //更新学生信息(除了密码)，通过username去操作，没有更新照片
    public void update(String username,String name,String sex,int age,String hobbies);

    //更新学生信息(除了密码)，通过username更新，有更新照片
    public void update(String username,String name,String sex,int age,String hobbies,String photo);

    //获取学生信息，通过username
    public Student getStudent(String username);

    //获取学生信息，通过username和username
    public Student getStudent(String username,String password);

    //获取学生的所有集合信息，用于分页，offset--偏移量，count--数据条数
    public List<Student> getStudents(int offset,int count);

    //获取当前表的总条数
    public int getAllCount();
}

StudentMapperImpl

具体操作数据库的增删查改，可以使用自己写的DBUtils 工具类

public class StudentMapperImpl implements StudentMapper {

    @Override
    public void add(String username, String password, String name, String sex, int age, String hobbies, String photo) {
        try {
            DBUtils.commonUpdate("insert into student(username,password,name,sex,age,hobbies,photo) values(?,?,?,?,?,?,?)",username,password,name,sex,age, hobbies,photo);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void delete(String username) {
        try {
            DBUtils.commonUpdate("delete from student where username = ?",username);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void update(String username, String newPassword) {
        try {
            DBUtils.commonUpdate("update student set password=? where username=?",newPassword,username);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void update(String username, String name, String sex, int age, String hobbies) {
        try {
            DBUtils.commonUpdate("update student set name=?,sex=?,age=?,hobbies=? where username=?",name,sex,age,hobbies,username);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void update(String username, String name, String sex, int age, String hobbies, String photo) {
        try {
            DBUtils.commonUpdate("update student set name=?,sex=?,age=?,hobbies=?,photo=? where username=?",name,sex,age,hobbies,photo,username);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public Student getStudent(String username) {

        Student student = null;
        try {
            student = DBUtils.commonQueryObj(Student.class, "select * from student where username = ?", username);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }

        return student;
    }

    @Override
    public Student getStudent(String username, String password) {
        Student student = null;
        try {
            student = DBUtils.commonQueryObj(Student.class, "select * from student where username = ? and password = ?", username, password);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        return student;
    }

    @Override
    public List<Student> getStudents(int offset, int count) {

        List<Student> students = null;
        try {
            students = DBUtils.commonQueryList(Student.class, "select * from student limit ?,?", offset, count);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }

        return students;
    }

    @Override
    public int getAllCount() {

        int allcount = 0;
        try {
            allcount = DBUtils.getAllCount("student");
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        return allcount;
    }
}

service业务逻辑层

具体的业务流程，存放Servlet

不用进行跳转，在Controller层进行跳转

有返回值的返回true/false就可以了

StudentService

public interface StudentService {

    //是否成功注册功能
    public boolean isRegister(String username);

    //注册功能
    public boolean register(HttpServletRequest request, HttpServletResponse response);

    //初始化学生信息功能
    public void initModify(HttpServletRequest request, HttpServletResponse response);

    //修改学生信息功能
    public void modify(HttpServletRequest request, HttpServletResponse response);

    //获取学生信息列表，方便分页
    public void getStudents(HttpServletRequest request, HttpServletResponse response);

    //删除学生功能
    public void delete(HttpServletRequest request, HttpServletResponse response);

    //添加学生的功能
    public boolean add(HttpServletRequest request, HttpServletResponse response);
}

StudentServiceImpl

实现 StudentService接口，写具体的业务逻辑

public class StudentServiceImpl implements StudentService {

    private StudentMapper studentMapper = new StudentMapperImpl();

    //是否成功注册功能
    @Override
    public boolean isRegister(String username) {

        Student student = studentMapper.getStudent(username);
        if(student == null){//允许注册
            return true;

        }
        return false;
    }

    //注册功能（注册表单是二进制流，涉及到了图片上传）
    @Override
    public boolean register(HttpServletRequest request, HttpServletResponse response) {

        ParseRequestData<Student> parseRequestData = ParseRequestDataUtils.parseRequest(request, Student.class, "upload\\student");

        Student stu = parseRequestData.getT();
        InputStream in = parseRequestData.getIn();
        OutputStream out = parseRequestData.getOut();

        boolean register = isRegister(stu.getUsername());
        if(register){
            //将数据插入到学生表中
            studentMapper.add(stu.getUsername(),stu.getPassword(),stu.getName(),stu.getSex(),stu.getAge(),stu.getHobbies(),stu.getPhoto());

            //将头像存储到本地磁盘
            try {
                IOUtils.copy(in,out);
                in.close();
                out.close();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }

            return true;
        }else{
            try {
                in.close();
                out.close();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
            request.setAttribute("msg","注册失败 -- 账号已注册");
            return false;
        }
    }

    //初始化学生信息功能
    @Override
    public void initModify(HttpServletRequest request, HttpServletResponse response) {
        String username = request.getParameter("username");
        Student student = studentMapper.getStudent(username);
        request.setAttribute("student",student);
    }

    //修改学生信息功能
    @Override
    public void modify(HttpServletRequest request, HttpServletResponse response) {

        ParseRequestData<Student> parseRequestData = ParseRequestDataUtils.parseRequest(request, Student.class, "upload\\student");
        Student stu = parseRequestData.getT();
        InputStream in = parseRequestData.getIn();
        OutputStream out = parseRequestData.getOut();

        try {
            if(stu.getPhoto() != null){//说明用户修改头像

                studentMapper.update(stu.getUsername(),stu.getName(), stu.getSex(), stu.getAge(),stu.getHobbies(),stu.getPhoto());
                IOUtils.copy(in,out);//文件复制
            }else{
                studentMapper.update(stu.getUsername(),stu.getName(), stu.getSex(), stu.getAge(),stu.getHobbies());
            }
            if(in != null){
                in.close();
            }
            if(out != null){
                out.close();
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        }

        String role = (String) request.getSession().getAttribute("role");
        if("student".equals(role)){
            //更新Session里的数据
            request.getSession().setAttribute("name",stu.getName());
            //更新Cookie里的数据
 response.addCookie(CookieUtils.createCookie("name",stu.getName(),60*60*24*5));
            if(stu.getPhoto() != null){
                request.getSession().setAttribute("photo",stu.getPhoto());
                response.addCookie(CookieUtils.createCookie("photo",stu.getPhoto(),60*60*24*5));
            }

        }

    }

    //获取学生信息列表，方便分页
    @Override
    public void getStudents(HttpServletRequest request, HttpServletResponse response) {
        //获取当前页数
        int curPage = Integer.parseInt(request.getParameter("curPage"));

        //设置URL
        String url = "student?action=doGetStudents&curPage=";
        //设置当前页的数据条数
        int count = 15;
        //计算偏移量
        int offset = (curPage-1)*count;
        //计算总页数
        int allCount = studentMapper.getAllCount();
        int totalPage = PageUtils.getTotalPage(allCount,count);

        //从数据库获取学生的集合
        List<Student> students = studentMapper.getStudents(offset,count);

        //处理学生集合
        List<StudentDto> studentDtos = DtoUtils.studentDtoListHandler(students);

        //封装Page对象
        Page<StudentDto> page = new Page<>(url, curPage, totalPage, studentDtos);

        //将数据存入到请求对象中
        request.setAttribute("page",page);
    }

    //删除学生功能
    @Override
    public void delete(HttpServletRequest request, HttpServletResponse response) {
        String username = request.getParameter("username");
        studentMapper.delete(username);
    }

    //添加学生的功能
    @Override
    public boolean add(HttpServletRequest request, HttpServletResponse response) {
        ParseRequestData<Student> parseRequestData = ParseRequestDataUtils.parseRequest(request, Student.class, "upload\\student");

        Student stu = parseRequestData.getT();
        InputStream in = parseRequestData.getIn();
        OutputStream out = parseRequestData.getOut();

        boolean register = isRegister(stu.getUsername());
        if(register){
            //将数据插入到学生表中
            studentMapper.add(stu.getUsername(),stu.getPassword(),stu.getName(),stu.getSex(),stu.getAge(),stu.getHobbies(),stu.getPhoto());

            //将头像存储到本地磁盘
            try {
                IOUtils.copy(in,out);
                in.close();
                out.close();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }

            return true;
        }else{
            try {
                in.close();
                out.close();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
            request.setAttribute("msg","添加失败 -- 账号已添加");
            return false;
        }
    }


}

ParseRequestDataUtils

package com.qf.utils;

public class ParseRequestDataUtils {

    public static <T> ParseRequestData parseRequest(HttpServletRequest request,Class<T> clazz,String path){

        ParseRequestData<T> parseRequestData = new ParseRequestData<>();

        //创建文件上传工厂类的对象
        DiskFileItemFactory factory = new DiskFileItemFactory();
        //创建文件上传类的对象
        ServletFileUpload upload = new ServletFileUpload(factory);

        HashMap<String, String> map = new HashMap<>();
        try {
            //解析请求
            List<FileItem> list = upload.parseRequest(request);
            for (FileItem fileItem : list) {
                if(fileItem.isFormField()){//文本数据

                    String name = fileItem.getFieldName();
                    String value = fileItem.getString("UTF-8");

                    String v = map.get(name);
                    if(v == null){//说明是第一次添加
                        map.put(name,value);
                    }else{//不是第一次添加就需要拼接（多选框的情况）
                        map.put(name,v + "," + value);
                    }

                }else{//二进制数据

                    //D:\\apache-tomcat-8.0.49\\webapps\\Day23_upload_war_exploded\\upload\\student
                    //D:\\apache-tomcat-8.0.49\\webapps\\Day23_upload_war_exploded\\upload\\teacher
                    String realPath = request.getServletContext().getRealPath(path);


                    //文件存储目录 -- 自定义路径\\用户名
                    realPath = realPath + File.separator + map.get("username");
                    File file = new File(realPath);
                    if(!file.exists()){
                        file.mkdirs();
                    }

                    String fileName = fileItem.getName();//获取文件名

                    //自定义路径\\用户名\\tx01.jpg
                    realPath = realPath + File.separator + fileName;//拼接路径

                    InputStream in = fileItem.getInputStream();
                    if(in.available() != 0){
                        FileOutputStream out = new FileOutputStream(realPath);

                        parseRequestData.setIn(in);
                        parseRequestData.setOut(out);

                        map.put("photo",path + File.separator + map.get("username") + File.separator + fileName);
                    }
                }
            }
        } catch (FileUploadException e) {
            throw new RuntimeException(e);
        } catch (FileNotFoundException e) {
            throw new RuntimeException(e);
        } catch (IOException e) {
            throw new RuntimeException(e);
        }

        Set<Map.Entry<String, String>> entries = map.entrySet();
        for (Map.Entry<String, String> entry : entries) {
            System.out.println(entry);
        }

        T t = null;
        try {
            t = clazz.newInstance();
            //将map中的数据映射到实体类对象中
            BeanUtils.populate(t,map);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        } catch (InvocationTargetException e) {
            throw new RuntimeException(e);
        } catch (InstantiationException e) {
            throw new RuntimeException(e);
        }
        parseRequestData.setT(t);

        return parseRequestData;
    }
}

controller

根据每一个前端传过来的action功能来判断跳转

判断功能进行页面跳转

action=“student?action=doRegister”，前端设置路径加上action=xxx功能

Controller进行具体的判断，成功就重定向，失败就转发

@WebServlet("/student")
public class StudentController extends BaseServlet {

    private StudentService studentService = new StudentServiceImpl();

    //注册功能
    public void doRegister(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        boolean register = studentService.register(request, response);

        if(register){
                response.sendRedirect("login.jsp");
        }else{
            request.getRequestDispatcher("register.jsp").forward(request,response);
        }
    }

    //初始化修改功能
    public void doInitModify(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        studentService.initModify(request,response);
        request.getRequestDispatcher("stuInfo.jsp").forward(request,response);
    }

    //修改功能
    public void doModify(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        studentService.modify(request,response);
        String role = (String) request.getSession().getAttribute("role");

        if("student".equals(role)){
            response.sendRedirect("index.jsp");
        }else if("teacher".equals(role)){
            request.getRequestDispatcher("student?action=doGetStudents&curPage=1").forward(request,response);
        }else if("admin".equals(role)){
            request.getRequestDispatcher("student?action=doGetStudents&curPage=1").forward(request,response);
        }
    }

    //展示数据功能
    public void doGetStudents(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        studentService.getStudents(request,response);
        request.getRequestDispatcher("stuList.jsp").forward(request,response);
    }

    //删除功能
    public void doDelete(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        studentService.delete(request,response);
        request.getRequestDispatcher("student?action=doGetStudents&curPage=1").forward(request,response);
    }

    //添加学生功能
    public void doAddStu(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        boolean register = studentService.register(request, response);

        if(register){
            request.getRequestDispatcher("student?action=doGetStudents&curPage=1").forward(request,response);
        }else{
            request.getRequestDispatcher("stuAdd.jsp").forward(request,response);
        }
    }

    //是否注册学生的提示功能（ajax）
    public void isRegister(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        String username = request.getParameter("username");
        boolean register = studentService.isRegister(username);
        String code;
        if(register){
            code="1";
        }else {
            code="-1";
        }
        response.getWriter().write(code);
    }
}

BaseServlet

给控制层重写的servlet，以前继承HttpServlet，就会写很多的if-else判断，太麻烦了

package com.qf.servlet;

public class BaseServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request, response);
    }

    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

        //url -- http://localhost:8080/Day24_MVC_war_exploded/user?action=doLogin
        String action = request.getParameter("action");//doLogin

        //获取Controller类的class对象
        Class<? extends BaseServlet> clazz = this.getClass();

        try {

            //根据action获取Controller类对应的方法对象
            Method method = clazz.getDeclaredMethod(action, HttpServletRequest.class, HttpServletResponse.class);

            //设置操作权限
            method.setAccessible(true);
            //调用方法
            method.invoke(this,request,response);
        } catch (NoSuchMethodException e) {
            throw new RuntimeException(e);
        } catch (InvocationTargetException e) {
            throw new RuntimeException(e);
        } catch (IllegalAccessException e) {
            throw new RuntimeException(e);
        }


    }
}

2.2 老师 teacher

TeacherMapper

明确数据库的功能

public interface TeacherMapper {

    //添加老师
    public void add(String username,String password,String name,String sex,int age,int courseId,String photo);

    //删除老师，通过username
    public void delete(String username);

    //更新老师的密码，通过username和newPassword
    public void update(String username,String newPassword);

    //更新老师信息(除了密码)，通过username去操作，没有更新照片
    public void update(String username,String name,String sex,int age,int courseId);

    //更新老师信息(除了密码)，通过username更新，有更新照片
    public void update(String username,String name,String sex,int age,int courseId,String photo);

    //获取老师信息，通过username
    public Teacher getTeacher(String username);

    //获取老师信息，通过username和username
    public Teacher getTeacher(String username,String password);

    //获取老师的所有集合信息，用于分页，offset--偏移量，count--数据条数
    public List<Teacher> getTeachers(int offset,int count);

    //获取当前表的总条数
    public int getAllCount();
}

StudentMapperImpl

public class StudentMapperImpl implements StudentMapper {

    @Override
    public void add(String username, String password, String name, String sex, int age, String hobbies, String photo) {
        try {
            DBUtils.commonUpdate("insert into student(username,password,name,sex,age,hobbies,photo) values(?,?,?,?,?,?,?)",username,password,name,sex,age, hobbies,photo);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void delete(String username) {
        try {
            DBUtils.commonUpdate("delete from student where username = ?",username);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void update(String username, String newPassword) {
        try {
            DBUtils.commonUpdate("update student set password=? where username=?",newPassword,username);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void update(String username, String name, String sex, int age, String hobbies) {
        try {
            DBUtils.commonUpdate("update student set name=?,sex=?,age=?,hobbies=? where username=?",name,sex,age,hobbies,username);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void update(String username, String name, String sex, int age, String hobbies, String photo) {
        try {
            DBUtils.commonUpdate("update student set name=?,sex=?,age=?,hobbies=?,photo=? where username=?",name,sex,age,hobbies,photo,username);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public Student getStudent(String username) {

        Student student = null;
        try {
            student = DBUtils.commonQueryObj(Student.class, "select * from student where username = ?", username);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }

        return student;
    }

    @Override
    public Student getStudent(String username, String password) {
        Student student = null;
        try {
            student = DBUtils.commonQueryObj(Student.class, "select * from student where username = ? and password = ?", username, password);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        return student;
    }

    @Override
    public List<Student> getStudents(int offset, int count) {

        List<Student> students = null;
        try {
            students = DBUtils.commonQueryList(Student.class, "select * from student limit ?,?", offset, count);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }

        return students;
    }

    @Override
    public int getAllCount() {

        int allcount = 0;
        try {
            allcount = DBUtils.getAllCount("student");
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        return allcount;
    }
}

业务逻辑层

TeacherService

public interface TeacherService {

    public boolean isAdd(String username);

    public boolean add(HttpServletRequest request, HttpServletResponse response);

    public void initModify(HttpServletRequest request, HttpServletResponse response);

    public void modify(HttpServletRequest request, HttpServletResponse response);

    public void getTeachers(HttpServletRequest request, HttpServletResponse response);

    public void delete(HttpServletRequest request, HttpServletResponse response);
}

TeacherServiceImpl

public class TeacherServiceImpl implements TeacherService {

    private TeacherMapper teacherMapper = new TeacherMapperImpl();
    private CourseService courseService = new CourseServiceImpl();

    @Override
    public boolean isAdd(String username) {
        Teacher teacher = teacherMapper.getTeacher(username);
        if(teacher == null){
            return true;

        }
        return false;
    }

    @Override
    public boolean add(HttpServletRequest request, HttpServletResponse response) {

        ParseRequestData<Teacher> parseRequestData = ParseRequestDataUtils.parseRequest(request, Teacher.class, "upload\\teacher");

        Teacher t = parseRequestData.getT();
        InputStream in = parseRequestData.getIn();
        OutputStream out = parseRequestData.getOut();

        boolean add = isAdd(t.getUsername());
        if(add){
            //将数据插入到老师表中
            teacherMapper.add(t.getUsername(),t.getPassword(),t.getName(),t.getSex(),t.getAge(),t.getCourseId(),t.getPhoto());

            //将头像存储到本地磁盘
            try {
                IOUtils.copy(in,out);
                in.close();
                out.close();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }

            return true;
        }else{
            try {
                in.close();
                out.close();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
            request.setAttribute("msg","添加失败 -- 账号已存在");
            return false;
        }
    }

    @Override
    public void initModify(HttpServletRequest request, HttpServletResponse response) {
        String username = request.getParameter("username");
        Teacher teacher = teacherMapper.getTeacher(username);
        request.setAttribute("teacher",teacher);

        courseService.getCourses(request,response);
    }

    @Override
    public void modify(HttpServletRequest request, HttpServletResponse response) {

        ParseRequestData<Teacher> parseRequestData = ParseRequestDataUtils.parseRequest(request, Teacher.class, "upload\\teacher");
        Teacher tea = parseRequestData.getT();
        InputStream in = parseRequestData.getIn();
        OutputStream out = parseRequestData.getOut();

        try {
            if(tea.getPhoto() != null){//说明用户修改头像
                teacherMapper.update(tea.getUsername(),tea.getName(), tea.getSex(), tea.getAge(),tea.getCourseId(),tea.getPhoto());
                IOUtils.copy(in,out);
            }else{
                teacherMapper.update(tea.getUsername(),tea.getName(), tea.getSex(), tea.getAge(),tea.getCourseId());
            }
            if(in != null){
                in.close();
            }
            if(out != null){
                out.close();
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        }

        String role = (String) request.getSession().getAttribute("role");
        if("teacher".equals(role)){
            //更新Session里的数据
            request.getSession().setAttribute("name",tea.getName());
            //更新Cookie里的数据
            response.addCookie(CookieUtils.createCookie("name",tea.getName(),60*60*24*5));

            if (tea.getPhoto() != null){
                request.getSession().setAttribute("photo",tea.getPhoto());
                response.addCookie(CookieUtils.createCookie("photo",tea.getPhoto(),60*60*24*5));
            }
        }

    }

    @Override
    public void getTeachers(HttpServletRequest request, HttpServletResponse response) {

        //获取当前页数
        int curPage = Integer.parseInt(request.getParameter("curPage"));

        //设置URL
        String url = "teacher?action=doGetTeachers&curPage=";
        //设置当前页的数据条数
        int count = 15;
        //计算偏移量
        int offset = (curPage-1)*count;
        //计算总页数
        int allCount = teacherMapper.getAllCount();
        int totalPage = PageUtils.getTotalPage(allCount,count);

        //从数据库获取老师的集合
        List<Teacher> teachers = teacherMapper.getTeachers(offset,count);

        //处理老师集合
        List<TeacherDto> teacherDtos = DtoUtils.teacherDtoListHandler(teachers);

        //封装Page对象
        Page<TeacherDto> page = new Page<>(url, curPage, totalPage, teacherDtos);

        //将数据存入到请求对象中
        request.setAttribute("page",page);
    }

    @Override
    public void delete(HttpServletRequest request, HttpServletResponse response) {

        String username = request.getParameter("username");
        teacherMapper.delete(username);
    }
}

控制器层

TeacherController

@WebServlet("/teacher")
public class TeacherController extends BaseServlet {

    private TeacherService teacherService = new TeacherServiceImpl();

    public void doInitModify(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        teacherService.initModify(request,response);
        request.getRequestDispatcher("teaInfo.jsp").forward(request,response);
    }

    public void doModify(HttpServletRequest request,HttpServletResponse response) throws IOException, ServletException {
        teacherService.modify(request,response);
        request.getRequestDispatcher("teacher?action=doGetTeachers&curPage=1").forward(request,response);
    }

    public void doGetTeachers(HttpServletRequest request,HttpServletResponse response) throws IOException, ServletException {
        teacherService.getTeachers(request,response);
        request.getRequestDispatcher("TeaList.jsp").forward(request,response);
    }

    public void doDelete(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        teacherService.delete(request,response);
        request.getRequestDispatcher("teacher?action=doGetTeachers&curPage=1").forward(request,response);
    }

    public void doAddTea(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        boolean add = teacherService.add(request,response);

        if(add){
            request.getRequestDispatcher("teacher?action=doGetTeachers&curPage=1").forward(request,response);
        }else{
            request.getRequestDispatcher("teaAdd.jsp").forward(request,response);
        }
    }

}

2.3 用户 user

user是学生和老师的父类，两个都有的功能就写在user里

注意：在数据库中没有user这个表，这是把学生和老师相同的功能提出来了，放在user里

UserService

public interface UserService {

    //绘制验证码功能
    public void drawCode(HttpServletRequest request, HttpServletResponse response);

    //登录功能
    public boolean login(HttpServletRequest request, HttpServletResponse response);

    //记住我功能
    public void rememberMe(HttpServletResponse response,String username,String name,String role,String photo);

    //安全退出功能
    public void loginOut(HttpServletRequest request, HttpServletResponse response);

    //修改验证码功能
    public boolean resetPassword(HttpServletRequest request, HttpServletResponse response);

}

UserServiceImpl

public class UserServiceImpl implements UserService {

    private StudentMapper studentMapper = new StudentMapperImpl();
    private TeacherMapper teacherMapper = new TeacherMapperImpl();

    private AdminMapper adminMapper=  new AdminMapperImpl();

    //绘制验证码功能
    @Override
    public void drawCode(HttpServletRequest request, HttpServletResponse response) {
        //设置宽高的变量
        int width = 120;
        int height = 30;

        //创建画布
        BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);

        //获取画笔
        Graphics graphics = image.getGraphics();

        //设置背景色 -- 填充矩形
        graphics.setColor(Color.BLUE);
        graphics.fillRect(0,0,width,height);

        //设置验证码
        Random random = new Random();
        String[] codes = {"A","B","C","D","E","F","G","H","J","K","M","N","P","Q","R","S","T","U","V","W","X","Y","Z","0","1","2","3","4","5","6","7","8","9"};
        Color[] colors = {Color.CYAN,Color.BLACK,Color.GREEN,Color.PINK,Color.WHITE,Color.RED,Color.ORANGE};

        StringBuffer sb = new StringBuffer();

        for (int i = 0; i < 4; i++) {

            String randomCode = codes[random.nextInt(codes.length)];
            Color randomColor = colors[random.nextInt(colors.length)];

            graphics.setColor(randomColor);//设置随机颜色
            graphics.setFont(new Font("宋体",Font.BOLD,20+random.nextInt(10)));//设置字体（字体,样式,大小）
            graphics.drawString(randomCode,20+i*25,15+random.nextInt(10));//设置单个验证码

            sb.append(randomCode);
        }

        //将系统验证码设置到Session对象中(会话对象)
        HttpSession session = request.getSession();//获取请求里的JSESSIONID(客户端Cookie里的数据)，如果没有就创建Session对象，如果有就从Session容器中获取会话对象
        session.setAttribute("sysCode",sb.toString());

        //设置干扰线
        graphics.setColor(Color.YELLOW);
        for (int i = 0; i < 3; i++) {
            graphics.drawLine(random.nextInt(width),random.nextInt(height),random.nextInt(width),random.nextInt(height));//绘制直线(x1,y1,x2,y2) -> 两点为一线
        }

        //将画布以jpg形式的文件传出给客户端
        try {
            ImageIO.write(image,"jpg",response.getOutputStream());
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    //登录功能
    @Override
    public boolean login(HttpServletRequest request, HttpServletResponse response) {
        //获取请求中的数据
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String userCode = request.getParameter("userCode");
        String rememberMe = request.getParameter("rememberMe");
        String role = request.getParameter("role");

        //从Session对象中获取系统的验证码
        String sysCode = (String) request.getSession().getAttribute("sysCode");
        if(sysCode.equalsIgnoreCase(userCode)){//验证码正确

            User user = null;
            if("student".equals(role)){
                user = studentMapper.getStudent(username,password);
            }else if("teacher".equals(role)){
                user = teacherMapper.getTeacher(username,password);
            } else if ("admin".equals(role)) {
                user = adminMapper.getAdmin(username, password);
            }

            if(user != null){//登录成功

                //判断是否记住我
                if(rememberMe != null){
                    if("admin".equals(role)){
                        rememberMe(response,user.getUsername(),user.getPassword(),role);
                        HttpSession session = request.getSession();
                        session.setAttribute("username",user.getUsername());
                        session.setAttribute("password",user.getPassword());
                        session.setAttribute("role",role);
                        return true;

                    }else if ("student".equals(role) || "teacher".equals(role)){

                        rememberMe(response,user.getUsername(),user.getName() ,role,user.getPhoto());
                        //将数据存储到Session中
                        HttpSession session = request.getSession();
                        session.setAttribute("username",user.getUsername());
                        session.setAttribute("name",user.getName());
                        session.setAttribute("role",role);
                        session.setAttribute("photo",user.getPhoto());
                        return true;
                    }

                }

                if("admin".equals(role)){
                    HttpSession session = request.getSession();
                    session.setAttribute("username",user.getUsername());
                    session.setAttribute("name",user.getPassword());
                    session.setAttribute("role",role);

                }else if ("student".equals(role) || "teacher".equals(role)){
                    //将数据存储到Session中
                    HttpSession session = request.getSession();
                    session.setAttribute("username",user.getUsername());
                    session.setAttribute("name",user.getName());
                    session.setAttribute("role",role);
                    session.setAttribute("photo",user.getPhoto());
                }


                return true;
            }else{//登录失败 -- 账号或密码错误
                request.setAttribute("msg","登录失败 -- 账号或密码错误");
                return false;
            }

        }else{//登录失败 - 验证码错误
            request.setAttribute("msg","登录失败 -- 验证码错误");
            return false;
        }
    }

    //管理员的记住我
    private void rememberMe(HttpServletResponse response, String username, String password, String role) {
        response.addCookie(CookieUtils.createCookie("username",username,60*60*24*5));
        response.addCookie(CookieUtils.createCookie("password",password,60*60*24*5));
        response.addCookie(CookieUtils.createCookie("role",role,60*60*24*5));
    }

    //记住我功能
    @Override
    public void rememberMe(HttpServletResponse response,String username, String name, String role, String photo) {
        //将凭证添加到Cookie中
        response.addCookie(CookieUtils.createCookie("username",username,60*60*24*5));
        response.addCookie(CookieUtils.createCookie("name",name,60*60*24*5));
        response.addCookie(CookieUtils.createCookie("role",role,60*60*24*5));
        response.addCookie(CookieUtils.createCookie("photo",photo,60*60*24*5));
    }

    //安全退出功能
    @Override
    public void loginOut(HttpServletRequest request, HttpServletResponse response) {
        //删除Cookie里的数据
        response.addCookie(CookieUtils.createCookie("username","",0));
        response.addCookie(CookieUtils.createCookie("name","",0));
        response.addCookie(CookieUtils.createCookie("role","",0));
        response.addCookie(CookieUtils.createCookie("photo","",0));
        response.addCookie(CookieUtils.createCookie("password","",0));

        //删除Session里的数据
        HttpSession session = request.getSession();
        session.removeAttribute("username");
        session.removeAttribute("name");
        session.removeAttribute("role");
        session.removeAttribute("photo");
        session.removeAttribute("password");
    }

    //修改密码功能
    @Override
    public boolean resetPassword(HttpServletRequest request, HttpServletResponse response) {
        //获取请求中的数据
        String username = request.getParameter("username");
        String password = request.getParameter("password");
        String newPassword = request.getParameter("newPassword");
        String role = request.getParameter("role");

        User user = null;
        if("student".equals(role)){
            user = studentMapper.getStudent(username,password);
        }else if("teacher".equals(role)){
            user = teacherMapper.getTeacher(username,password);
        } else if ("admin".equals(role)) {
            user = adminMapper.getAdmin(username, password);
        }

        if(user != null){
            if("student".equals(role)){
                studentMapper.update(username,newPassword);
            }else if("teacher".equals(role)){
                teacherMapper.update(username,newPassword);
            } else if ("admin".equals(role)) {
                adminMapper.update(username,newPassword);
            }
            return true;
        }else{
            request.setAttribute("msg","修改密码失败 -- 原密码不正确");
            return false;
        }
    }
}

UserController

，前端传过来的路径中带有action=“xxx功能”，然后进行xxx功能的相关业务的跳转

@WebServlet("/user")
public class UserController extends BaseServlet {

    private UserService userService = new UserServiceImpl();

    public void doDrawCode(HttpServletRequest request,HttpServletResponse response){
        userService.drawCode(request,response);
    }

    public void doLogin(HttpServletRequest request,HttpServletResponse response) throws IOException, ServletException {
        boolean login = userService.login(request, response);
        if(login){
            response.sendRedirect("index.jsp");
        }else{
            request.getRequestDispatcher("login.jsp").forward(request,response);
        }
    }

    public void doLoginOut(HttpServletRequest request,HttpServletResponse response) throws IOException {
        userService.loginOut(request, response);
        response.sendRedirect("welcome.html");
    }

    public void doResetPassword(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        boolean resetPassword = userService.resetPassword(request, response);
        if(resetPassword){
            request.getRequestDispatcher("user?action=doLoginOut").forward(request,response);
        }else{
            request.getRequestDispatcher("resetPassword.jsp").forward(request,response);
        }
    }

}

2.4 管理员

功能：

1.登录（user里有）

2.修改密码（user里有）

3.管理老师 – 老师列表页面（分页、修改、删除、添加）

4.管理学科 – 学科列表页面（展示所有学科、修改、删除、添加）

5.管理学生 – 学生列表页面（分页、修改、删除、添加）

在这里插入图片描述

实体类 Admin 直接继承user类

SQL – admin ：username、password

public class Admin extends User{}

AdminMapper

public interface AdminMapper {

    //获取管理员信息，通过username
    public Admin getAdmin(String username);

    //获取管理员信息，通过username和username
    public Admin getAdmin(String username,String password);

    //更新管理员的密码，通过username和newPassword
    public void update(String username,String newPassword);
}

AdminMapperImpl

public class AdminMapperImpl implements AdminMapper {
    @Override
    public Admin getAdmin(String username) {
        Admin admin=null;
        try {
            admin = DBUtils.commonQueryObj(Admin.class, "select * from admin where username =?", username);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        return admin;
    }

    @Override
    public Admin getAdmin(String username, String password) {
        Admin admin=null;
        try {
            admin = DBUtils.commonQueryObj(Admin.class, "select * from admin where username =? and password=?", username,password);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
        return admin;
    }

    @Override
    public void update(String username, String newPassword) {

        try {
            DBUtils.commonUpdate("update admin set password = ? where username =?", newPassword, username);
        } catch (SQLException e) {
            throw new RuntimeException(e);
        }
    }
}

AdminService

都是uer里写了的，就没有AdminServiceImpl,controller层也没有，直接在index.jsp跳转就可以了

public interface AdminService {

    //登录功能
    public boolean login(HttpServletRequest request, HttpServletResponse response);

    //修改验证码功能
    public boolean resetPassword(HttpServletRequest request, HttpServletResponse response);
}

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
<html>
<head>
    <title>Title</title>
</head>
<body>

    <button οnclick="safeExit()">安全退出</button>
    <h1>详情页面</h1>

    <c:if test="${role eq 'admin'}">
        <h1>欢迎管理员进入到学生管理系统</h1>
    </c:if>

    <c:if test="${role eq 'student' || role eq 'teacher'}">
        <h1>欢迎${name}${(role eq "student")?"学员":""}${(role eq "teacher")?"老师":""}进入到学生管理系统</h1>
        <img src="${photo}" width="100px" height="100px"><br/>
    </c:if>


    <a href="resetPassword.jsp">修改密码</a>

    <c:if test="${role eq 'admin'}">
        <a href="student?action=doGetStudents&curPage=1">管理学生</a>
        <a href="teacher?action=doGetTeachers&curPage=1">管理老师</a>
        <a href="course?action=doGetCourses">管理学科</a>
    </c:if>


    <c:if test="${role eq 'student'}">
        <a href="student?action=doInitModify&username=${username}">修改信息</a>
    </c:if>
    <c:if test="${role eq 'teacher'}">
        <a href="teacher?action=doInitModify&username=${username}">修改信息</a>
        <a href="student?action=doGetStudents&curPage=1">查看所有学生</a>
    </c:if>

    <script type="text/javascript">
        function safeExit(){
            window.location = "user?action=doLoginOut";
        }
    </script>
</body>
</html>

2.5 其他补充

数据库工具类DBUtils

package com.qf.utils;

public class DBUtils {

    private static DruidDataSource pool;
    private static ThreadLocal<Connection> local;

    static{
        Properties properties = new Properties();
        try {
            properties.load(DBUtils.class.getClassLoader().getResourceAsStream("DBConfig.properties"));
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
        String driverClassName = properties.getProperty("driverClassName");
        String url = properties.getProperty("url");
        String username = properties.getProperty("username");
        String password = properties.getProperty("password");
        int maxActive = Integer.parseInt(properties.getProperty("maxActive"));

        //初始化数据库连接池
        pool = new DruidDataSource();

        //设置参数
        pool.setDriverClassName(driverClassName);
        pool.setUrl(url);
        pool.setUsername(username);
        pool.setPassword(password);
        pool.setMaxActive(maxActive);

        local = new ThreadLocal<>();
    }

    /**
     * 获取连接对象
     */
    public static Connection getConnection() throws SQLException {
        Connection connection = local.get();//获取当前线程的Connection对象
        if(connection == null){
            connection = pool.getConnection();//获取数据库连接池里的连接对象
            local.set(connection);//将Connection对象添加到local中
        }
        return connection;
    }

    /**
     * 关闭资源
     */
    public static void close(Connection connection, Statement statement, ResultSet resultSet){
        if(resultSet != null){
            try {
                resultSet.close();
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
        if(statement != null){
            try {
                statement.close();
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
        if(connection != null){
            try {
                if(connection.getAutoCommit()){
                    connection.close();
                    local.set(null);
                }
            } catch (SQLException e) {
                throw new RuntimeException(e);
            }
        }
    }

    /**
     * 开启事务
     */
    public static void startTransaction() throws SQLException {
        Connection connection = getConnection();
        connection.setAutoCommit(false);
    }

    /**
     * 提交事务
     */
    public static void commit() throws SQLException {
        Connection connection = local.get();
        if(connection != null){
            connection.commit();
            connection.close();
            local.set(null);
        }
    }

    public static void rollback() throws SQLException {
        Connection connection = local.get();
        if(connection != null){
            connection.rollback();
            connection.close();
            local.set(null);
        }
    }

    /**
     * 更新数据（添加、删除、修改）
     */
    public static int commonUpdate(String sql,Object... params) throws SQLException {
        Connection connection = null;
        PreparedStatement statement = null;
        try {
            connection = getConnection();
            statement = connection.prepareStatement(sql);
            paramHandler(statement,params);
            int num = statement.executeUpdate();
            return num;
        }finally {
            close(connection,statement,null);
        }
    }

    /**
     * 添加数据 - 主键回填(主键是int类型可以返回)
     */
    public static int commonInsert(String sql,Object... params) throws SQLException {
        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;
        try {
            connection = getConnection();
            statement = connection.prepareStatement(sql,PreparedStatement.RETURN_GENERATED_KEYS);
            paramHandler(statement,params);
            statement.executeUpdate();

            resultSet = statement.getGeneratedKeys();
            int primaryKey = 0;
            if(resultSet.next()){
                primaryKey = resultSet.getInt(1);
            }
            return primaryKey;
        }finally {
            close(connection,statement,resultSet);
        }
    }

    /**
     * 查询多个数据
     */
    public static <T> List<T> commonQueryList(Class<T> clazz,String sql, Object... params) throws SQLException{

        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;

        try {
            connection = getConnection();
            statement = connection.prepareStatement(sql);
            paramHandler(statement,params);
            resultSet = statement.executeQuery();

            //获取表数据对象
            ResultSetMetaData metaData = resultSet.getMetaData();
            //获取字段个数
            int count = metaData.getColumnCount();

            List<T> list = new ArrayList<>();

            while(resultSet.next()){

                T t = null;
                try {
                    t = clazz.newInstance();
                } catch (InstantiationException e) {
                    throw new RuntimeException(e);
                } catch (IllegalAccessException e) {
                    throw new RuntimeException(e);
                }

                //获取字段名及数据
                for (int i = 1; i <= count; i++) {
                    String fieldName = metaData.getColumnName(i);
                    Object fieldVal = resultSet.getObject(fieldName);
                    setField(t,fieldName,fieldVal);
                }
                list.add(t);
            }
            return list;
        } finally {
            DBUtils.close(connection,statement,resultSet);
        }
    }

    /**
     * 查询单个数据
     */
    public static <T> T commonQueryObj(Class<T> clazz,String sql, Object... params) throws SQLException{

        Connection connection = null;
        PreparedStatement statement = null;
        ResultSet resultSet = null;

        try {
            connection = getConnection();
            statement = connection.prepareStatement(sql);
            paramHandler(statement,params);
            resultSet = statement.executeQuery();

            //获取表数据对象
            ResultSetMetaData metaData = resultSet.getMetaData();
            //获取字段个数
            int count = metaData.getColumnCount();

            if(resultSet.next()){

                T t = null;
                try {
                    t = clazz.newInstance();
                } catch (InstantiationException e) {
                    throw new RuntimeException(e);
                } catch (IllegalAccessException e) {
                    throw new RuntimeException(e);
                }

                //获取字段名及数据
                for (int i = 1; i <= count; i++) {
                    String fieldName = metaData.getColumnName(i);
                    Object fieldVal = resultSet.getObject(fieldName);
                    setField(t,fieldName,fieldVal);
                }
                return t;
            }
        } finally {
            DBUtils.close(connection,statement,resultSet);
        }
        return null;
    }

    /**
     * 获取当前表的总条数
     */
    public static int getAllCount(String table) throws SQLException {
        Connection connection = getConnection();
        String sql = "select count(1) from " + table;
        PreparedStatement statement = connection.prepareStatement(sql);
        ResultSet resultSet = statement.executeQuery();
        if(resultSet.next()){
            int allCount = resultSet.getInt(1);
            return allCount;
        }
        return 0;
    }

    /**
     * 处理statement对象参数数据的处理器
     */
    private static void paramHandler(PreparedStatement statement,Object... params) throws SQLException {
        for (int i = 0; i < params.length; i++) {
            statement.setObject(i+1,params[i]);
        }
    }

    /**
     * 获取当前类及其父类的属性对象
     * @param clazz class对象
     * @param name 属性名
     * @return 属性对象
     */
    private static Field getField(Class<?> clazz,String name){

        for(Class<?> c = clazz;c != null;c = c.getSuperclass()){
            try {
                Field field = c.getDeclaredField(name);
                return field;
            } catch (NoSuchFieldException e) {
            } catch (SecurityException e) {
            }
        }
        return null;
    }

    /**
     * 设置对象中的属性
     * @param obj 对象
     * @param name 属性名
     * @param value 属性值
     */
    private static void setField(Object obj,String name,Object value){

        Field field = getField(obj.getClass(), name);
        if(field != null){
            field.setAccessible(true);
            try {
                field.set(obj, value);
            } catch (IllegalArgumentException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }
    }


}