SSM16.5【Mybatis：通过注解实现Mybatis的复杂映射开发之多对多查询】

 

 

 

 

 

 

 

 

 

 

 

package com.haifei.domain;

public class Role {

    private int id;
    private String roleName;
    private String roleDesc;

    public int getId() {
        return id;
    }

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

    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{" +
                "id=" + id +
                ", roleName='" + roleName + '\'' +
                ", roleDesc='" + roleDesc + '\'' +
                '}';
    }
}

package com.haifei.domain;

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

public class User {

    private int id;
    private String username;
    private String password;
    private Date birthday;

    //描述的是当前用户具有的订单
    private List<Order> orderList;
    public List<Order> getOrderList() {
        return orderList;
    }
    public void setOrderList(List<Order> orderList) {
        this.orderList = orderList;
    }

    //描述的是当前用户具备哪些角色
    private List<Role> roleList;
    public List<Role> getRoleList() {
        return roleList;
    }
    public void setRoleList(List<Role> roleList) {
        this.roleList = roleList;
    }

    public Date getBirthday() {
        return birthday;
    }

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

    public int getId() {
        return id;
    }

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

    public String getUsername() {
        return username;
    }

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

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    //1:1
   /* @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", birthday=" + birthday +
                '}';
    }*/
   //1:n
    /*@Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", birthday=" + birthday +
                ", orderList=" + orderList +
                '}';
    }*/
    //m:n
    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", password='" + password + '\'' +
                ", birthday=" + birthday +
                ", orderList=" + orderList +
                ", roleList=" + roleList +
                '}';
    }
}

UserMapper 

+

    @Select("select * from user")
    @Results({
            @Result(column = "id", property = "id", id=true),
            @Result(column = "username",property = "username"),
            @Result(column = "password",property = "password"),
            @Result(
                    property = "roleList",
                    column = "id",
                    javaType = List.class,
                    many = @Many(select = "com.haifei.mapper.RoleMapper.findByUid")
            )
    })
    public List<User> findUserAndRoleAll();

package com.haifei.mapper;

import com.haifei.domain.Role;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface RoleMapper {

    @Select("select * from sys_user_role ur,sys_role r where ur.roleId=r.id and ur.userId=#{uid}")
    public List<Role> findByUid(int id);

}

package com.haifei.test;

import com.haifei.domain.User;
import com.haifei.mapper.UserMapper;
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.Before;
import org.junit.Test;

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

public class MybatisTest4 {

    private UserMapper mapper;

    @Before
    public void before() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession(true); //true-->事务自动提交
        mapper = sqlSession.getMapper(UserMapper.class);
    }

    /**
     * 多对多查询
     */
    @Test
    public void testFindUserAndOrderAll(){
        List<User> userList = mapper.findUserAndRoleAll();
        for (User user : userList) {
            System.out.println(user);
        }
        /*
        User{id=1, username='zhangsan', password='123', birthday=Sat Jul 24 20:00:29 CST 2021, orderList=null, roleList=[Role{id=1, roleName='院长', roleDesc='负责全面工作'}, Role{id=2, roleName='研究员', roleDesc='课程研发工作'}]}
        User{id=2, username='lisi', password='345', birthday=Sat Jul 24 20:00:29 CST 2021, orderList=null, roleList=[Role{id=2, roleName='研究员', roleDesc='课程研发工作'}, Role{id=3, roleName='讲师', roleDesc='授课工作'}]}
        User{id=3, username='tom', password='abc', birthday=Sat Jul 24 20:00:29 CST 2021, orderList=null, roleList=[]}
        User{id=4, username='lucy', password='def', birthday=Sat Jul 24 20:00:29 CST 2021, orderList=null, roleList=[]}
        User{id=5, username='sam', password='sam', birthday=Sat Jul 24 20:00:29 CST 2021, orderList=null, roleList=[]}
        User{id=9, username='11', password='11', birthday=Sat Jul 24 20:00:29 CST 2021, orderList=null, roleList=[]}
         */
    }

}