Mybatis实现多对多

其他 2020-04-11 01:35:33 阅读次数: 0

Mybatis实现多对多

项目结构

在这里插入图片描述

配置文件

  1. pom.xml

    <?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.xiaoge</groupId>
    <artifactId>many2many</artifactId>
    <version>1.0-SNAPSHOT</version>
    <packaging>jar</packaging>

    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.5</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>8.0.13</version>
        </dependency>

        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>
    </dependencies>

</project>

  2. jdbcConfig.properties

    jdbc.driver=com.mysql.cj.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/eesy_mybatis
jdbc.username=root
jdbc.password=123456

  3. SqlMapConfig.xml

    <?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration
        PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-config.dtd">

<configuration>

    <!--配置properties-->
    <properties resource="jdbcConfig.properties">
    </properties>


    <!-- 使用typeAliases配置别名, 它只能配置domain中类的别名 -->
    <typeAliases>
        <package name="com.xiaoge.domain"></package>
    </typeAliases>

    <!--配置环境-->
    <environments default="mysql">
        <!--配置mysql环境-->
        <environment id="mysql">
            <!--配置事务-->
            <transactionManager type="JDBC"></transactionManager>

            <!--配置连接池-->
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}" />
                <property name="url" value="${jdbc.url}" />
                <property name="username" value="${jdbc.username}" />
                <property name="password" value="${jdbc.password}" />
            </dataSource>

        </environment>
    </environments>

    <mappers>
        <package name="com.xiaoge.dao"></package>
    </mappers>
</configuration>

  4. roleDao.xml

    <?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">

<mapper namespace="com.xiaoge.dao.RoleDao">

  
  
    <!-- 定义role表的resultMap -->
    <resultMap id="roleMap" type="role">
        <id property="roleId" column="rid"></id>
        <result property="roleName" column="role_name"></result>
        <result property="roleDesc" column="role_desc"></result>

        <!-- 配置用户集合的映射 -->
        <collection property="users" ofType="user">
            <id property="id" column="id"></id>
            <result property="username" column="username"></result>
            <result property="birthday" column="birthday"></result>
            <result property="sex" column="sex"></result>
            <result property="address" column="address"></result>
        </collection>
    </resultMap>

  
  
    <!-- 查询所有 -->
    <select id="findAll" resultMap="roleMap">
        <!-- 注意 id 重复了  不取别名 java程序查出来的结果有误(注意: 这里用了别名, 上面resultMap设置column值时也用别名) -->
        select
            role.id as rid,
            role.role_name as role_name,
            role.role_desc as role_desc,
            user.*
        from
            role
        left join
            user_role
        on
            role.id = user_role.rid
        left join
            user
        on
            user_role.uid = user.id
    </select>
              
              
</mapper>

  5. userDao.xml

    <?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE mapper
        PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
        "http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="com.xiaoge.dao.UserDao">

  
  
    <!-- 定义user表的resultMap -->
    <resultMap id="userMap" type="user">
        <id property="id" column="id"></id>
        <result property="username" column="username"></result>
        <result property="birthday" column="birthday"></result>
        <result property="sex" column="sex"></result>
        <result property="address" column="address"></result>

        <!-- 配置角色集合的映射 -->
        <collection property="roles" ofType="role">
            <id property="roleId" column="rid"></id>
            <result property="roleName" column="role_name"></result>
            <result property="roleDesc" column="role_desc"></result>
        </collection>


    </resultMap>


  
  
    <!-- 查询所有用户操作 -->
    <select id="findAll" resultMap="userMap">
        <!-- 注意 id 重复了  不取别名 java程序查出来的结果有误(注意: 这里用了别名, 上面resultMap设置column值时也用别名) -->
         select
            user.*,
            role.id as rid,
            role.role_name as role_name,
            role.role_desc as role_desc
        from
            user
        left join
            user_role
        on
            user.id = user_role.uid
        left join
            role
        on
            user_role.rid= role.id
    </select>


              
</mapper>

实体类

  1. User

    package com.xiaoge.domain;

import java.util.Date;
import java.util.List;

/**
 * @Author: 潇哥
 * @DateTime: 2020/3/4 下午4:03
 * @Description: TODO
 */
public class User {

    private Integer id;
    private String username;
    private String address;
    private String sex;
    private Date birthday;

    // 多对多关系映射
    // 用户和角色是多对多关系, 但是这里希望的是查询用户的时候, 同时显示角色信息, 所以在该实体类中定义映射关系
    private List<Role> roles;

    public List<Role> getRoles() {
        return roles;
    }

    public void setRoles(List<Role> roles) {
        this.roles = roles;
    }

    public Integer getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getAddress() {
        return address;
    }

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

    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 +
                ", username='" + username + '\'' +
                ", address='" + address + '\'' +
                ", sex='" + sex + '\'' +
                ", birthday=" + birthday +
                '}';
    }
}

  2. Role

    package com.xiaoge.domain;

import java.io.Serializable;
import java.util.List;

/**
 * @Author: 潇哥
 * @DateTime: 2020/3/17 下午3:58
 * @Description: TODO
 */
public class Role implements Serializable {

    private Integer roleId;
    private String roleName;
    private String roleDesc;

    // 多对多关系映射
    // 角色和用户是多对多关系, 但是这里希望的是查询角色的时候, 同时显示用户信息, 所以在该实体类中定义映射关系
    private List<User> users;

    public List<User> getUsers() {
        return users;
    }

    public void setUsers(List<User> users) {
        this.users = users;
    }

    public Integer getRoleId() {
        return roleId;
    }

    public void setRoleId(Integer roleId) {
        this.roleId = roleId;
    }

    public String getRoleName() {
        return roleName;
    }

    public void setRoleName(String roleName) {
        this.roleName = roleName;
    }

    public String getRoleDesc() {
        return roleDesc;
    }

    public void setRoleDesc(String roleDesc) {
        this.roleDesc = roleDesc;
    }

    @Override
    public String toString() {
        return "Role{" +
                "roleId=" + roleId +
                ", roleName='" + roleName + '\'' +
                ", roleDesc='" + roleDesc + '\'' +
                '}';
    }
}

持久层接口

  1. UserDao

    package com.xiaoge.dao;

import com.xiaoge.domain.User;

import java.util.List;

/**
 * @Author: 潇哥
 * @DateTime: 2020/3/4 下午4:19
 * @Description: 用户的持久层接口
 */
public interface UserDao {

    /**
     * 查询所有用户, 同时获取到用户所对应的角色
     * @return
     */
    public List<User> findAll();


}

  2. RoleDao

    package com.xiaoge.dao;

import com.xiaoge.domain.Role;

import java.util.List;

/**
 * @Author: 潇哥
 * @DateTime: 2020/3/17 下午4:04
 * @Description: TODO
 */
public interface RoleDao {

    /**
     * 查询所有角色, 及角色所对应的用户信息
     * @return
     */
    public List<Role> findAll();

}

测试持久层接口方法

  1. UserTest

    package com.xiaoge.test;

import com.xiaoge.dao.UserDao;
import com.xiaoge.domain.User;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

/**
 * @Author: 潇哥
 * @DateTime: 2020/3/16 下午6:12
 * @Description: TODO
 */
public class UserTest {

    private SqlSession session;
    private UserDao userDao;
    private InputStream is;

    @Before
    public void init() throws IOException {
        is = Resources.getResourceAsStream("SqlMapConfig.xml");
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(is);
        session = factory.openSession();
        userDao = session.getMapper(UserDao.class);
    }

    @After
    public void destroy() throws IOException {

        if (session != null) {
            session.commit();
            session.close();
        }

        if (is != null) {
            is.close();
        }

    }

    /**
     * 测试查询所有
     */
    @Test
    public void findAllTest(){
        List<User> list = userDao.findAll();

        for (User user : list) {
            System.out.println("-----------每个user信息------------");
            System.out.println(user);
            System.out.println(user.getRoles());
        }
      
      	// 运行结果
      	-----------每个user信息------------
        User{id=41, username='老王', address='北京', sex='男', birthday=Wed Feb 28 07:47:08 CST 2018}
        [Role{roleId=1, roleName='院长', roleDesc='管理整个学院'}, Role{roleId=2, roleName='总裁', roleDesc='管理整个公司'}]
        -----------每个user信息------------
        User{id=46, username='老王', address='北京', sex='女', birthday=Thu Mar 08 07:37:26 CST 2018}
        [Role{roleId=1, roleName='院长', roleDesc='管理整个学院'}]
        -----------每个user信息------------
        User{id=42, username='小二王', address='北京金燕龙', sex='女', birthday=Sat Mar 03 05:09:37 CST 2018}
        []
        -----------每个user信息------------
        User{id=43, username='小二王', address='北京金燕龙', sex='女', birthday=Mon Mar 05 01:34:34 CST 2018}
        []
        -----------每个user信息------------
        User{id=48, username='小马宝莉', address='北京修正', sex='女', birthday=Fri Mar 09 01:44:00 CST 2018}
        []
        -----------每个user信息------------
        User{id=53, username='啸哥', address='北京四合院', sex='男', birthday=Fri Mar 06 13:10:42 CST 2020}
        []
        -----------每个user信息------------
        User{id=54, username='李四 last insertid', address='北京', sex='男', birthday=Fri Mar 06 14:26:40 CST 2020}
        []
        -----------每个user信息------------
        User{id=55, username='王五 last insertid', address='北京', sex='男', birthday=Fri Mar 06 15:17:43 CST 2020}
        []
        -----------每个user信息------------
        User{id=56, username='李六 last insertid', address='北京', sex='男', birthday=Fri Mar 06 18:47:48 CST 2020}
        []
        -----------每个user信息------------
        User{id=57, username='李六 last insertid', address='北京', sex='男', birthday=Fri Mar 06 19:11:40 CST 2020}
        []
        -----------每个user信息------------
        User{id=59, username='李白 last insertid', address='北京', sex='男', birthday=Wed Mar 11 18:17:20 CST 2020}
        []

    }


}

  2. RoleTest

    package com.xiaoge.test;

import com.xiaoge.dao.RoleDao;
import com.xiaoge.domain.Role;
import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.io.IOException;
import java.io.InputStream;
import java.util.List;

/**
 * @Author: 潇哥
 * @DateTime: 2020/3/16 下午6:12
 * @Description: TODO
 */
public class RoleTest {

    private SqlSession session;
    private RoleDao roleDao;
    private InputStream is;

    @Before
    public void init() throws IOException {
        is = Resources.getResourceAsStream("SqlMapConfig.xml");
        SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();
        SqlSessionFactory factory = builder.build(is);
        session = factory.openSession();
        roleDao = session.getMapper(RoleDao.class);
    }

    @After
    public void destroy() throws IOException {

        if (session != null) {
            session.commit();
            session.close();
        }

        if (is != null) {
            is.close();
        }

    }

    /**
     * 测试查询所有
     */
    @Test
    public void findAllTest(){
        List<Role> list = roleDao.findAll();

        for (Role role : list) {
            System.out.println("-----------每个role信息------------");
            System.out.println(role);
            System.out.println(role.getUsers());
        }
      
      	// 运行结果
      	-----------每个role信息------------
        Role{roleId=1, roleName='院长', roleDesc='管理整个学院'}
        [User{id=41, username='老王', address='北京', sex='男', birthday=Wed Feb 28 07:47:08 CST 2018}, User{id=46, username='老王', address='北京', sex='女', birthday=Thu Mar 08 07:37:26 CST 2018}]
        -----------每个role信息------------
        Role{roleId=2, roleName='总裁', roleDesc='管理整个公司'}
        [User{id=41, username='老王', address='北京', sex='男', birthday=Wed Feb 28 07:47:08 CST 2018}]
        -----------每个role信息------------
        Role{roleId=3, roleName='校长', roleDesc='管理整个学校'}
        []
    }


}
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