构建项目Maven/jar

初次构建项目时，思考是不是通过maven创建，使用maven的化需要导入那些依赖；
如果不是使用maven创建项目的话，使用哪些些jar包。

检测验证项目

选择使用maven创建项目完成，可以使用模板，导入完成后 补充自己目录结构。

在java下建自己的目录地址，此次使用的是com.smbms01，resources下建立资源路径；
在java的代码路径下，建立相应的pack包路径：dao、filter、pojo/entity、service、servlet。

导入jar包/依赖

使用maven创建项目的情况，我们要在pom.xml中添加依赖：

 <dependencies>
     <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.11</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>4.0.1</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>jsp-api</artifactId>
      <version>2.2</version>
    </dependency>
    <dependency>
      <groupId>javax.servlet.jsp.jstl</groupId>
      <artifactId>jstl</artifactId>
      <version>1.2</version>
    </dependency>
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>8.0.30</version>
    </dependency>
  </dependencies>

junit: 测试依赖；
javax.servlet：服务依赖；
javax.servlet.jsp：画面jsp依赖；
javax.servlet.jsp.jstl：jstl依赖；
mysql-connector-java:mysql的驱动连接。

编写相应实体类

编写实体类与SQL中表的字段要一一对应：
User的表结构

实体类：

package com.smbms01.pojo;

import java.util.Date;

/**
 * 用户表
 */
public class User {

    /* id */
    private Integer id;
    /* 用户编码 */
    private String userCode;
    /* 用户名称 */
    private String userName;
    /* 用户密码 */
    private String userPassword;
    /* 用户性别 */
    private String gender;
    /* 出生日期 */
    private String birthday;
    /* 电话 */
    private String phone;
    /* 地址 */
    private String address;
    /* 用户角色 */
    private String userRole;
    /* 创建者 */
    private String createBy;
    /* 创建时间 */
    private String createdDate;
    /* 更新者 */
    private String modifyBy;
    /* 更新时间 */
    private String modifyDate;

    /* 年龄 */
    private Integer age;
    /* 用戶角色名称 */
    private String userRoleName;

    public String getUserRoleName() {
        return userRoleName;
    }

    public void setUserRoleName(String userRoleName) {
        this.userRoleName = userRoleName;
    }

    public Integer getAge() {
        Date date = new Date();
        Integer age = Integer.valueOf(birthday) - Integer.valueOf(date.getDate());
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public User() {
        super();
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUserCode() {
        return userCode;
    }

    public void setUserCode(String userCode) {
        this.userCode = userCode;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName;
    }

    public String getUserPassword() {
        return userPassword;
    }

    public void setUserPassword(String userPassword) {
        this.userPassword = userPassword;
    }

    public String getGender() {
        return gender;
    }

    public void setGender(String gender) {
        this.gender = gender;
    }

    public String getBirthday() {
        return birthday;
    }

    public void setBirthday(String birthday) {
        this.birthday = birthday;
    }

    public String getPhone() {
        return phone;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getUserRole() {
        return userRole;
    }

    public void setUserRole(String userRole) {
        this.userRole = userRole;
    }

    public String getCreateBy() {
        return createBy;
    }

    public void setCreateBy(String createBy) {
        this.createBy = createBy;
    }

    public String getCreatedDate() {
        return createdDate;
    }

    public void setCreatedDate(String createdDate) {
        this.createdDate = createdDate;
    }

    public String getModifyBy() {
        return modifyBy;
    }

    public void setModifyBy(String modifyBy) {
        this.modifyBy = modifyBy;
    }

    public String getModifyDate() {
        return modifyDate;
    }

    public void setModifyDate(String modifyDate) {
        this.modifyDate = modifyDate;
    }
}

在eclipse中，使用alt+shift+s，可以使用工具的快捷方式，生成相应的gettesetter方法。
在idea中 ，使用alt+inster，在打开的框中，可以生产相应的gettersetter方法。

编写SQL公共基础类

package com.smbms01.dao;

import java.io.IOException;
import java.io.InputStream;
import java.sql.*;
import java.util.Properties;

// 数据库的公共类
public class BaseDao {

    private static String driver;
    private static String url;
    private static String username;
    private static String password;

    // 静态代码块，类加载的时候就初始化了
    static {
        Properties properties = new Properties();
        // 通过类加载器读取对应的资源
        InputStream iS = BaseDao.class.getClassLoader().getResourceAsStream("db.properties");

        try {
            properties.load(iS);
        } catch (IOException e) {
            e.printStackTrace();
        }

        driver = properties.getProperty("driver");
        driver = properties.getProperty("url");
        driver = properties.getProperty("username");
        driver = properties.getProperty("password");
    }

    // 获取数据库的连接
    public static Connection getConnection(){
        Connection connection = null;
        try {
            Class.forName(driver);
            connection = DriverManager.getConnection(url,username,password);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return  connection;
    }

    // 编写查询公共类
    public  static ResultSet execute(Connection connection, String sql, Object[] params,PreparedStatement preparedStatement,ResultSet resultSet) throws SQLException {
      // 预编译的 不需要再次传值，后面直接使用就可以了
        preparedStatement = connection.prepareStatement(sql);

        for (int i = 0; i < params.length; i++) {
            preparedStatement.setObject(i+1, params[i]);
        }
        resultSet = preparedStatement.executeQuery();

        return resultSet;
    }

    // 编写增删改的公共类
    public  static int execute(Connection connection, String sql, Object[] params,PreparedStatement preparedStatement) throws SQLException {

        preparedStatement = connection.prepareStatement(sql);
        for (int i = 0; i < params.length; i++) {
            preparedStatement.setObject(i+1, params[i]);
        }
        int updateRows = preparedStatement.executeUpdate();
        return updateRows;
    }

    public  static boolean closeResource(Connection connection,PreparedStatement preparedStatement, ResultSet resultSet) throws SQLException {
        boolean flag = true;
        if (resultSet !=null){
            try {
                resultSet.close();
                preparedStatement = null;
            } catch (SQLException e){
                e.printStackTrace();
                flag = false;
            }
        }

        if (preparedStatement !=null){
            try {
                resultSet.close();
                preparedStatement = null;
            } catch (SQLException e){
                e.printStackTrace();
                flag = false;
            }
        }

        if (connection !=null){
            try {
                resultSet.close();
                preparedStatement = null;
            } catch (SQLException e){
                e.printStackTrace();
                flag = false;
            }
        }

        return true;
    }

}

编写字符编码过滤器

package com.smbms01.filter;


import javax.servlet.*;
import java.io.IOException;

/**
 * 字符编码过滤器
 */
public class CharacterEnCodingFilter 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() {

    }
}

在这里插入代码片  <!--字符编码过滤器-->
  <filter>
    <filter-name>CharacterEnCodingFilter</filter-name>
    <filter-class>com.smbms01.filter.CharacterEnCodingFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>CharacterEnCodingFilter</filter-name>
    <url-pattern>/*</url-pattern>
  </filter-mapping>
  

导入静态资源

需要的内容，js，图片，css样式等；