MyBatis多对多关系查询

Mybatis多对多

第一次写博客，请大家多多关照

数据库表的关系

数据库表我简单的画了下，3张主表 2张关系映射表

原则：
不同的角色用户登录 显示不同的权限列表
一个用户可以多个角色 一个角色有多个权限

实体类

用户 ：

// An highlighted block
public class User {
	private Integer uid;
	private String uname;
	private List<Role> roleList;
	public List<Role> getRoleList() {
		return roleList;
	}
	public void setRoleList(List<Role> roleList) {
		this.roleList = roleList;
	}
	public Integer getUid() {
		return uid;
	}
	public void setUid(Integer uid) {
		this.uid = uid;
	}
	public String getUname() {
		return uname;
	}
	public void setUname(String uname) {
		this.uname = uname;
	}
	
}

用户角色 ：

// An highlighted block
public class Role {
	private Integer rid;
	private String rname;
	private List<Qx> qxList;
	
	public List<Qx> getQxList() {
		return qxList;
	}
	public void setQxList(List<Qx> qxList) {
		this.qxList = qxList;
	}
	public Integer getRid() {
		return rid;
	}
	public void setRid(Integer rid) {
		this.rid = rid;
	}
	public String getRname() {
		return rname;
	}
	public void setRname(String rname) {
		this.rname = rname;
	}
}

用户权限 ：

// An highlighted block
public class Qx {
	private Integer qid;
	private String qname;
	public Integer getQid() {
		return qid;
	}
	public void setQid(Integer qid) {
		this.qid = qid;
	}
	public String getQname() {
		return qname;
	}
	public void setQname(String qname) {
		this.qname = qname;
	}
	
}

mapper接口 ：

// An highlighted block
public interface UserMapper {

	public User getUserRoleQxList(int uid);
	
}

UserMapper.xml ：

// An highlighted block
<?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="mapper.UserMapper"> 	
	<select id="getUserRoleQxList" parameterType="int" resultMap="user_map">
		SELECT
			u.uid,
			u.uname,
			r.rid,
			r.rname,
			q.qid,
			q.qname
		FROM
			USER u
			LEFT JOIN u_r ON u_r.uid = u.uid
			LEFT JOIN role r ON r.rid = u_r.rid
			LEFT JOIN r_q ON r_q.rid = r.rid
			LEFT JOIN qx q ON q.qid = r_q.qid
		WHERE
			u.uid = #{uid}
	</select>

	<resultMap type="user" id="user_map">
		<id column="uid" property="uid"/>
		<result column="uname" property="uname"/>
			<collection property="roleList" ofType="role">
				<id column="rid" property="rid"/>
				<result column="rname" property="rname"/>
				<collection property="qxList" ofType="qx">
					<id column="qid" property="qid"/>
					<result column="qname" property="qname"/>
				</collection>
			</collection>
	</resultMap>

</mapper>

稍微把公共的语句封装了下：

// An highlighted block
public class MyBatisUtil {

	private static SqlSessionFactory sqlSessionFactory ;
	
	static {
		try {
			InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
			sqlSessionFactory =  new SqlSessionFactoryBuilder().build(is);
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
	/**
	 * 获取Sqlsession
	 * @return
	 */
	public static SqlSession getSqlSession() {
		if(sqlSessionFactory!=null) {
			return sqlSessionFactory.openSession();
		}else {
			try {
				InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
				return sqlSessionFactory.openSession();
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			return sqlSessionFactory.openSession();
		}
	}
	/**
	 * 关闭Sqlsession
	 * @param sqlSession
	 */
	public static void CloseSqlsession(SqlSession sqlSession) {
		if(sqlSession!=null) {
			sqlSession.close();
		}	
	}
	
}

测试类

// An highlighted block
public class Test {
	
	@org.junit.Test
	public void test01() {
		SqlSession sqlSession = MyBatisUtil.getSqlSession();
		UserMapper userMapper = sqlSession.getMapper(UserMapper.class);
		//根据用户ID进行查询
		User user = userMapper.getUserRoleQxList(1);
		System.out.println("用户名:"+user.getUname());
		List<Role> roleList = user.getRoleList();
		for (Role role : roleList) {
			System.out.println("用户角色:"+role.getRname());
			List<Qx> qxList = role.getQxList();
			for (Qx qx : qxList) {
				System.out.println("用户权限:"+qx.getQname());
			}
			System.out.println("---------------------");
		}
		MyBatisUtil.CloseSqlsession(sqlSession);
	}
}

结果：