Mbatis学习笔记（五）多对多

多对多
实体类

public class Role implements Serializable {

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

    //多对多的关系映射：一个角色可以赋予多个用户
    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 + '\'' +
                '}';
    }
}

public class User implements Serializable {

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

    //多对多的关系映射：一个用户可以具备多个角色
    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 +
                '}';
    }
}

主配置文件

<?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.domain"></package>
    </typeAliases>

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

            <!--配置连接池-->
            <dataSource type="POOLED">
                <property name="driver" value="${jdbc.driver}"></property>
                <property name="url" value="${jdbc.url}"></property>
                <property name="username" value="${jdbc.username}"></property>
                <property name="password" value="${jdbc.password}"></property>
            </dataSource>
        </environment>
    </environments>
    <!-- 配置映射文件的位置 -->
    <mappers>
        <package name="com.dao"></package>
    </mappers>
</configuration>

映射配置文件

<?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.dao.IUserDao">

    <!-- 定义User的resultMap-->
    <resultMap id="userMap" type="user">
        <id property="id" column="id"></id>
        <result property="username" column="username"></result>
        <result property="address" column="address"></result>
        <result property="sex" column="sex"></result>
        <result property="birthday" column="birthday"></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 -->
    <select id="findAll" resultMap="userMap">
        select u.*,r.id as rid,r.role_name,r.role_desc from user u
         left outer join user_role ur  on u.id = ur.uid
         left outer join role r on r.id = ur.rid
    </select>


</mapper>

<?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.dao.IRoleDao">

    <!--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>
        <collection property="users" ofType="user">
            <id column="id" property="id"></id>
            <result column="username" property="username"></result>
            <result column="address" property="address"></result>
            <result column="sex" property="sex"></result>
            <result column="birthday" property="birthday"></result>
        </collection>
    </resultMap>

    <!--查询所有-->
    <select id="findAll" resultMap="roleMap">
       select u.*,r.id as rid,r.role_name,r.role_desc from role r
        left outer join user_role ur  on r.id = ur.rid
        left outer join user u on u.id = ur.uid
    </select>
</mapper>

dao接口

public interface IRoleDao {

    /**
     * 查询所有角色
     * @return
     */
    List<Role> findAll();
}

public interface IUserDao {

    /**
     * 查询所有用户，同时获取到用户下所有账户的信息
     * @return
     */
    List<User> findAll();


    /**
     * 根据id查询用户信息
     * @param userId
     * @return
     */
    User findById(Integer userId);

}

jdbc

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

测试

public class RoleTest {

    private InputStream in;
    private SqlSession sqlSession;
    private IRoleDao roleDao;

    @Before//用于在测试方法执行之前执行
    public void init()throws Exception{
        //1.读取配置文件，生成字节输入流
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.获取SqlSessionFactory
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        //3.获取SqlSession对象
        sqlSession = factory.openSession(true);
        //4.获取dao的代理对象
        roleDao = sqlSession.getMapper(IRoleDao.class);
    }

    @After//用于在测试方法执行之后执行
    public void destroy()throws Exception{
        //提交事务
        // sqlSession.commit();
        //6.释放资源
        sqlSession.close();
        in.close();
    }

    /**
     * 测试查询所有
     */
    @Test
    public void testFindAll(){
        List<Role> roles = roleDao.findAll();
        for(Role role : roles){
            System.out.println("---每个角色的信息----");
            System.out.println(role);
            System.out.println(role.getUsers());
        }
    }

}

public class UserTest {

    private InputStream in;
    private SqlSession sqlSession;
    private IUserDao userDao;

    @Before//用于在测试方法执行之前执行
    public void init()throws Exception{
        //1.读取配置文件，生成字节输入流
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.获取SqlSessionFactory
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        //3.获取SqlSession对象
        sqlSession = factory.openSession(true);
        //4.获取dao的代理对象
        userDao = sqlSession.getMapper(IUserDao.class);
    }

    @After//用于在测试方法执行之后执行
    public void destroy()throws Exception{
        //提交事务
        // sqlSession.commit();
        //6.释放资源
        sqlSession.close();
        in.close();
    }

    /**
     * 测试查询所有
     */
    @Test
    public void testFindAll(){
        List<User> users = userDao.findAll();
        for(User user : users){
            System.out.println("-----每个用户的信息------");
            System.out.println(user);
            System.out.println(user.getRoles());
        }
    }

}