基于Servlet的增删改查
1.开发环境
- IDEA
- JDK1.8
- Tomcat8.5
- Mysql 8.0.12
2.数据库
2.1表创建
2.2表数据
3.JavaWeb代码
3.1目录结构
3.2util包下代码
JdbcUtil完成对数据库的连接和资源释放
JsonResult对返回前端资源的封装
JdbcUtil代码：
/*
数据库连接板帮助类
*/
public class JdbcUtil {
private static final String DRIVERNAME="com.mysql.cj.jdbc.Driver";
private static final String URL="jdbc:mysql://localhost:3306/jdbc?useUnicode=true&characterEncoding=utf-8&useSSL=false&serverTimezone=Asia/Shanghai";
private static final String USERNAME="root";
private static final String PASSWORD="root";
static {
try {
// 1.加载驱动类
Class.forName(DRIVERNAME);
} catch (ClassNotFoundException e) {
System.out.println("驱动加载错误："+ e);
}
}
// 2.返回数据库连接对象
public static Connection getJDBCConnection(){
Connection connection=null;
try {
connection= DriverManager.getConnection(URL,USERNAME,PASSWORD);
} catch (SQLException e) {
System.out.println("创建连接对象错误："+ e);
}
finally {
return connection;
}
}
// 3.关闭资源
public static void closeJDBC(ResultSet resultSet, Statement statement, Connection connection){
try {
if (resultSet!=null)
resultSet.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
finally {
if (statement!=null) {
try {
statement.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
finally {
try {
if (connection!=null)
connection.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
}
finally {
System.out.println("close success！");
}
}
}
}
}
}
JsonResult代码：
public class JsonResult {
private Integer code;
private String message;
private Object data;
public JsonResult(Integer code, String message, Object data) {
this.code = code;
this.message = message;
this.data = data;
}
public JsonResult() {
}
public Integer getCode() {
return code;
}
public void setCode(Integer code) {
this.code = code;
}
public String getMessage() {
return message;
}
public void setMessage(String message) {
this.message = message;
}
public Object getData() {
return data;
}
public void setData(Object data) {
this.data = data;
}
@Override
public String toString() {
return "JsonResult{" +
"code:" + code.toString() +
", message:" + message +
", data:" + data+
'}';
}
}3.3entity包下代码
User实体类代码
User代码：
public class User implements Serializable {
private Integer id;
private String name;
private String password;
private String sex;
private Date birthday;
public User(Integer id, String name, String password, String sex, Date birthday) {
this.id = id;
this.name = name;
this.password = password;
this.sex = sex;
this.birthday = birthday;
}
public User() {
}
public Integer getId() {
return id;
}
public void setId(Integer id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public String getSex() {
return sex;
}
public void setSex(String sex) {
this.sex = sex;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
@Override
public String toString() {
return "User{" +
"id:" + id +
", name:" + name +
", password:" + password +
", sex:" + sex +
", birthday:" + birthday +
'}';
}
}
3.4dao包下代码
dao层完成对数据库user表的增删改查操作
UserDao定义的是接口
UserDao'Impl定义的是接口的实现类。
注意：基于事务的操作。
UserDao代码：
public interface UserDao {
public boolean save(User user);
public boolean update(User user);
public boolean delete(Integer id);
public User getUserById(Integer id);
public List<User> listAll();
}
UserDaoImpl代码：
public class UserDaoImpl implements UserDao {
@Override
public boolean save(User user) {
Connection connection=JdbcUtil.getJDBCConnection();
String sql="insert into user(`name`,`password`,`sex`,`birthday`) values(?,?,?,?)";
PreparedStatement statement=null;
try {
statement=connection.prepareStatement(sql);
connection.setAutoCommit(false);
statement =connection.prepareStatement(sql);
statement.setString(1,user.getName());
statement.setString(2,user.getPassword());
statement.setString(3,user.getSex());
statement.setDate(4,user.getBirthday());
int line=statement.executeUpdate();
connection.commit();
if (line>=1)
return true;
else
return false;
} catch (SQLException throwables) {
throwables.printStackTrace();
try {
connection.rollback();
} catch (SQLException e) {
return false;
}
return false;
}
finally {
try {
statement.close();
connection.close();
}
catch (SQLException e) {
e.printStackTrace();
return false;
}
}
}
@Override
public boolean update(User user) {
Connection connection=JdbcUtil.getJDBCConnection();
String sql="update user set `name`=?,`password`=?,`sex`=?,`birthday`=? where `id`=?";
PreparedStatement statement=null;
try {
statement=connection.prepareStatement(sql);
connection.setAutoCommit(false);
statement =connection.prepareStatement(sql);
statement.setString(1,user.getName());
statement.setString(2,user.getPassword());
statement.setString(3,user.getSex());
statement.setDate(4,user.getBirthday());
statement.setInt(5,user.getId());
int line=statement.executeUpdate();
connection.commit();
if (line>=1)
return true;
else
return false;
} catch (SQLException throwables) {
throwables.printStackTrace();
try {
connection.rollback();
} catch (SQLException e) {
return false;
}
return false;
}
finally {
try {
statement.close();
connection.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
return false;
}
}
}
@Override
public boolean delete(Integer id) {
Connection connection=JdbcUtil.getJDBCConnection();
String sql="delete from user where `id`=?";
PreparedStatement statement=null;
try {
statement=connection.prepareStatement(sql);
connection.setAutoCommit(false);
statement.setInt(1,id);
int line=statement.executeUpdate();
connection.commit();
if (line>=1) {
return true;
}
else
return false;
} catch (SQLException throwables) {
throwables.printStackTrace();
try {
connection.rollback();
} catch (SQLException e) {
return false;
}
return false;
}
finally {
try {
statement.close();
connection.close();
} catch (SQLException throwables) {
throwables.printStackTrace();
return false;
}
}
}
@Override
public User getUserById(Integer id) {
Connection connection=JdbcUtil.getJDBCConnection();
String sql="select * from user where `id`=?";
User user=new User();
PreparedStatement statement=null;
try {
statement=connection.prepareStatement(sql);
statement.setInt(1,id);
ResultSet set=statement.executeQuery();
if (set.next()){
user.setId(set.getInt("id"));
user.setName(set.getString("name"));
user.setPassword(set.getString("password"));
user.setSex(set.getString("sex"));
user.setBirthday(set.getDate("birthday"));
}
} catch (SQLException throwables) {
throwables.printStackTrace();
}
finally {
return user;
}
}
public static void main(String[] args) {
System.out.println(new UserDaoImpl().delete(8));
}
@Override
public List<User> listAll() {
List<User> list=new ArrayList<User>();
Connection connection=JdbcUtil.getJDBCConnection();
String sql="select * from user ";
Statement statement=null;
try {
statement=connection.createStatement();
ResultSet set=statement.executeQuery(sql);
while (set.next()){
User user=new User();
user.setId(set.getInt("id"));
user.setName(set.getString("name"));
user.setPassword(set.getString("password"));
user.setSex(set.getString("sex"));
user.setBirthday(set.getDate("birthday"));
list.add(user);
}
} catch (SQLException throwables) {
throwables.printStackTrace();
}
finally {
return list;
}
}
}3.5servic包下代码
UserService以及UserServiceImpl完成对业务逻辑的封装
UserService代码：
public interface UserService {
public boolean save(User user);
public boolean update(User user);
public boolean delete(Integer id);
public User getUserById(Integer id);
public List<User> listAll();
}
UserServiceImpl代码：
public class UserServiceImpl implements UserService {
private UserDao userDao=new UserDaoImpl();
@Override
public boolean save(User user) {
return userDao.save(user);
}
@Override
public boolean update(User user) {
return userDao.update(user);
}
@Override
public boolean delete(Integer id) {
return userDao.delete(id);
}
@Override
public User getUserById(Integer id) {
return userDao.getUserById(id);
}
@Override
public List<User> listAll() {
return userDao.listAll();
}
}
3.6controller代码
采用基于Servlet的请求转发
UserController代码：
@WebServlet(name = "userController",urlPatterns = {
"/save",
"/update",
"/delete",
"/findAll",
"/getUserById"
})
public class UserController extends HttpServlet {
private UserService userService=new UserServiceImpl();
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String option =req.getParameter("option");
JsonResult jsonResult=new JsonResult();
if (option.equals("findAll")){
jsonResult.setCode(200);
jsonResult.setMessage("获取成功！");
jsonResult.setData(userService.listAll());
}
else if (option.equals("getUserById")){
Integer id=Integer.parseInt(req.getParameter("id"));
jsonResult.setCode(200);
jsonResult.setMessage("获取成功！");
jsonResult.setData(userService.getUserById(id));
}
else {
jsonResult.setCode(20000);
jsonResult.setMessage("获取失败！");
jsonResult.setData(null);
}
resp.getWriter().println(jsonResult.toString());
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String option =req.getParameter("option");
JsonResult jsonResult=new JsonResult();
if (option.equals("save")){
User user=new User();
user.setName(req.getParameter("name"));
user.setSex(req.getParameter("sex"));
user.setPassword(req.getParameter("password"));
SimpleDateFormat format= new SimpleDateFormat("yyyy-MM-dd");
if (!req.getParameter("birthday").equals(""))
{
try {
user.setBirthday(new Date(format.parse(req.getParameter("birthday")).getTime()));
} catch (ParseException e) {
user.setBirthday(null);
}
}
if (userService.save(user)){
jsonResult.setCode(200);
jsonResult.setMessage("添加成功！");
jsonResult.setData(null);
}
else {
jsonResult.setCode(20000);
jsonResult.setMessage("添加失败！");
jsonResult.setData(null);
}
}
else {
jsonResult.setCode(20000);
jsonResult.setMessage("添加失败！");
jsonResult.setData(null);
}
resp.getWriter().println(jsonResult.toString());
}
@Override
protected void doDelete(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String option =req.getParameter("option");
JsonResult jsonResult=new JsonResult();
if (option.equals("delete")){
Integer id=Integer.parseInt(req.getParameter("id"));
if (userService.delete(id)){
jsonResult.setCode(200);
jsonResult.setMessage("删除成功！");
jsonResult.setData(null);
}
else {
jsonResult.setCode(20000);
jsonResult.setMessage("删除失败！");
jsonResult.setData(null);
}
}
else {
jsonResult.setCode(20000);
jsonResult.setMessage("删除失败！");
jsonResult.setData(null);
}
resp.getWriter().println(jsonResult.toString());
}
@Override
protected void doPut(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
String option =req.getParameter("option");
JsonResult jsonResult=new JsonResult();
if (option.equals("update")){
User user=new User();
user.setId(Integer.parseInt(req.getParameter("id")));
user.setName(req.getParameter("name"));
user.setSex(req.getParameter("sex"));
user.setPassword(req.getParameter("password"));
SimpleDateFormat format= new SimpleDateFormat("yyyy-MM-dd");
if (!req.getParameter("birthday").equals(""))
{
try {
user.setBirthday(new Date(format.parse(req.getParameter("birthday")).getTime()));
} catch (ParseException e) {
user.setBirthday(null);
}
}
if (userService.update(user)){
jsonResult.setCode(200);
jsonResult.setMessage("更新成功！");
jsonResult.setData(null);
}
else {
jsonResult.setCode(20000);
jsonResult.setMessage("更新失败！");
jsonResult.setData(null);
}
}
else {
jsonResult.setCode(20000);
jsonResult.setMessage("添加失败！");
jsonResult.setData(null);
}
resp.getWriter().println(jsonResult.toString());
}
}
4.接口测试
4.1findAll操作
4.2getUserById操作
4.3save操作
4.4update操作
4.5delete操作
5.乱码问题解决
5.1解决方式1
在所有请求的方法中加入
req.setCharacterEncoding("UTF-8");
resp.setCharacterEncoding("UTF-8");
5.1解决方式2
需要配置过滤的路径
注意：/*不能写成/**
使用过滤器的方式
@WebFilter("/*")
public class EncodingFilter implements Filter {
@Override
public void init(FilterConfig filterConfig) throws ServletException {
}
@Override
public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
servletRequest.setCharacterEncoding("UTF-8");
servletResponse.setCharacterEncoding("UTF-8");
filterChain.doFilter(servletRequest,servletResponse);
}
@Override
public void destroy() {
}
}
如果有错误，欢迎大家批评指正！！!
