【Mybtis】05：注解开发

第五章：MyBatis注解开发

---

OVERVIEW

• 第五章：MyBatis注解开发
• • • 一、基于注解的CURD
    • • 1.xml文件映射
      • 2.注解实现映射
    • 二、基于注解的关联查询
    • • 1.1v1查询
      • • （1）配置方式：
        • （2）程序演示：
      • 2.1vN查询
      • • （1）配置方式：
        • （2）程序演示：
      • 3.NvN查询
      • • （1）配置方式：
        • （2）程序演示：

一、基于注解的CURD

注解	说明
@Insert	增加
@Update	修改
@Delete	删除
@Select	查询
@Result	结果集封装
@Results	多个结果集封装
@One	1v1结果集封装
@Many	1vN结果集封装

1.xml文件映射

package com.itcast.domain;

import java.util.Date;

public class User {
    private int id;
    private String username;
    private String password;
    private Date 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;
    }

    public Date getBirthday() {
        return birthday;
    }

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

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + ''' +
                ", password='" + password + ''' +
                ", birthday=" + birthday +
                '}';
    }
}

package com.itcast.mapper;

import com.itcast.domain.User;

import java.util.List;

public interface UserMapper {
    public void save(User user);
    public void update(User user);
    public void delete(int id);
    public User findById(int id);
    public List findAll();
}

    
        insert into user values(#{id}, #{username}, #{password}, #{birthday})
    
    
        update user set username = #{username}, password = #{password} where id = #{id}
    
    
        delete from user where id = #{id}
    
    
        select * from user where id = #{id}
    
    
        select * from user
    

package com.itcast.test;

import com.itcast.domain.User;
import com.itcast.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.Date;
import java.util.List;

public class MybatisTest {
    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);//自动提交事务
        mapper = sqlSession.getMapper(UserMapper.class);
    }

    @Test
    public void testSave() {
        User user = new User();
        user.setUsername("Tom");
        user.setPassword("1234456");
        user.setBirthday(new Date());
        mapper.save(user);
    }

    @Test
    public void testUpdate() {
        User user = new User();
        user.setId(7);
        user.setUsername("Lucy");
        user.setPassword("abcdefg");
        user.setBirthday(new Date());
        mapper.update(user);
    }

    @Test
    public void testDelete() {
        mapper.delete(8);
    }

    @Test
    public void testFindById() {
        User user = mapper.findById(3);
        System.out.println(user);
    }

    @Test
    public void testFindAll() {
        List userList = mapper.findAll();
        for (User user : userList) {
            System.out.println(user);
        }
    }
}

2.注解实现映射

通过注解同样能够实现映射POJO对象和数据表之间的关联映射，对xml文件实现的映射进行修改：

• step1：修改UserMapper文件，将xml文件中的映射以注解的形式写入UserMapper接口中（resources下的xml文件已无用）

package com.itcast.mapper;

import com.itcast.domain.User;
import org.apache.ibatis.annotations.Delete;
import org.apache.ibatis.annotations.Insert;
import org.apache.ibatis.annotations.Select;
import org.apache.ibatis.annotations.Update;

import java.util.List;

public interface UserMapper {
    @Insert("insert into user values(#{id}, #{username}, #{password}, #{birthday})")
    public void save(User user);

    @Update("update user set username = #{username}, password = #{password} where id = #{id}")
    public void update(User user);

    @Delete("delete from user where id = #{id}")
    public void delete(int id);

    @Select("select * from user where id = #{id}")
    public User findById(int id);

    @Select("select * from user")
    public List findAll();
}

• step2：对sqlMapConfig.xml文件中的映射加载语句进行修改

全部修改完成，进行test测试如下：

二、基于注解的关联查询

1.1v1查询

用户表和订单表的关系为，一个用户有多个订单，一个订单只从属于一个用户。

一对一查询的需求：查询一个订单，与此同时查询出该订单所属的用户。

SELECt *, o.id oid
FROM orders o, user u
WHERe o.uid = u.id

（1）配置方式：

配置方式1：

package com.itcast.mapper;

import com.itcast.domain.Order;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface OrderMapper {
    @Select("SELECT *, o.id oid FROM orders o, user u WHERe o.uid = u.id")
    @Results({
            @Result(column = "oid", property = "id"),
            @Result(column = "ordertime", property = "ordertime"),
            @Result(column = "total", property = "total"),
            @Result(column = "uid", property = "user.id"),
            @Result(column = "username", property = "user.username"),
            @Result(column = "password", property = "user.password"),
            @Result(column = "birthday", property = "user.birthday"),
    })
    public List findAll();
}

配置方式2：

package com.itcast.mapper;

import com.itcast.domain.Order;
import com.itcast.domain.User;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface OrderMapper {
    @Select("SELECT * FROM orders")
    @Results({
            @Result(column = "oid", property = "id"),
            @Result(column = "ordertime", property = "ordertime"),
            @Result(column = "total", property = "total"),
            @Result(
                    property = "user", //要封装的属性
                    column = "uid", //根据哪个字段去查询user表的数据
                    javaType = User.class, //要封装的实体类型
                    //select属性 代表查询哪个接口的方法获得数据
                    one = @One(select = "com.itcast.mapper.UserMapper.findById")
            )
    })
    public List findAll();
}

（2）程序演示：

package com.itcast.domain;

import java.sql.Timestamp;
import java.util.Date;

public class Order {
    private int id;
    private Timestamp ordertime;
    private double total;
    private User user;//该定单属于的用户

    public int getId() {
        return id;
    }

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

    public Date getOrdertime() {
        return ordertime;
    }

    public void setOrdertime(Timestamp ordertime) {
        this.ordertime = ordertime;
    }

    public double getTotal() {
        return total;
    }

    public void setTotal(double total) {
        this.total = total;
    }

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    @Override
    public String toString() {
        return "Order{" +
                "id=" + id +
                ", ordertime=" + ordertime +
                ", total=" + total +
                ", user=" + user +
                '}';
    }
}

package com.itcast.domain;

import java.util.Date;

public class User {
    private int id;
    private String username;
    private String password;
    private Date 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;
    }

    public Date getBirthday() {
        return birthday;
    }

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

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + ''' +
                ", password='" + password + ''' +
                ", birthday=" + birthday +
                '}';
    }
}

package com.itcast.mapper;

import com.itcast.domain.Order;
import com.itcast.domain.User;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;

import java.util.List;

public interface OrderMapper {
    @Select("SELECT * FROM orders")
    @Results({
            @Result(column = "oid", property = "id"),
            @Result(column = "ordertime", property = "ordertime"),
            @Result(column = "total", property = "total"),
            @Result(
                    property = "user", //要封装的属性
                    column = "uid", //根据哪个字段去查询user表的数据
                    javaType = User.class, //要封装的实体类型
                    //select属性 代表查询哪个接口的方法获得数据
                    one = @One(select = "com.itcast.mapper.UserMapper.findById")
            )
    })
    public List findAll();
}

package com.itcast.test;

import com.itcast.domain.Order;
import com.itcast.mapper.OrderMapper;
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 MybatisTest2 {
    private OrderMapper mapper;
    @Before
    public void before() throws IOException {
        InputStream resourceAsStream = Resources.getResourceAsStream("sqlMapConfig.xml");
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(resourceAsStream);
        SqlSession sqlSession = sqlSessionFactory.openSession(true);//自动提交事务
        mapper = sqlSession.getMapper(OrderMapper.class);
    }

    @Test
    public void testFindAll() {
        List orderList = mapper.findAll();
        for (Order order : orderList) {
            System.out.println(order);
        }
    }
}

2.1vN查询

用户表和订单表的关系为，一个用户有多个订单，一个订单只从属于一个用户。

一对多查询的需求：查询一个用户，与此同时查询出该用户具有的订单。

select * from user;
select * from orders where uid = 查询出用户的id;

（1）配置方式：

package com.itcast.mapper;

import com.itcast.domain.User;
import org.apache.ibatis.annotations.*;

import java.util.List;

public interface UserMapper {
    @Select("select * from user")
    @Results({
            @Result(column = "id", property = "id"),
            @Result(column = "username", property = "username"),
            @Result(column = "password", property = "password"),
            @Result(
                    property = "orderList",
                    column = "id",
                    javaType = List.class,
                    many = @Many(select = "com.itcast.mapper.OrderMapper.findByUid")
            )
    })
    public List findUserAndOrderAll();
}

package com.itcast.mapper;

import com.itcast.domain.Order;
import com.itcast.domain.User;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.omg.CORBA.PUBLIC_MEMBER;

import java.util.List;

public interface OrderMapper {
    @Select("select * from orders where uid = #{uid}")
    public List findByUid(int uid);
}

（2）程序演示：

package com.itcast.domain;

import java.sql.Timestamp;
import java.util.Date;

public class Order {
    private int id;
    private Timestamp ordertime;
    private double total;

    public int getId() {
        return id;
    }

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

    public Date getOrdertime() {
        return ordertime;
    }

    public void setOrdertime(Timestamp ordertime) {
        this.ordertime = ordertime;
    }

    public double getTotal() {
        return total;
    }

    public void setTotal(double total) {
        this.total = total;
    }

    public User getUser() {
        return user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    @Override
    public String toString() {
        return "Order{" +
                "id=" + id +
                ", ordertime=" + ordertime +
                ", total=" + total +
                ", user=" + user +
                '}';
    }
}

package com.itcast.domain;

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

public class User {
    private int id;
    private String username;
    private String password;
    private Date birthday;
    private List orderList;//该用户的所有订单

    public List getOrderList() {
        return orderList;
    }

    public void setOrderList(List orderList) {
        this.orderList = orderList;
    }

    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;
    }

    public Date getBirthday() {
        return birthday;
    }

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

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + ''' +
                ", password='" + password + ''' +
                ", birthday=" + birthday +
                ", orderList=" + orderList +
                '}';
    }
}

package com.itcast.mapper;

import com.itcast.domain.User;
import org.apache.ibatis.annotations.*;

import java.util.List;

public interface UserMapper {
    @Select("select * from user")
    @Results({
            @Result(column = "id", property = "id"),
            @Result(column = "username", property = "username"),
            @Result(column = "password", property = "password"),
            @Result(
                    property = "orderList",
                    column = "id",
                    javaType = List.class,
                    many = @Many(select = "com.itcast.mapper.OrderMapper.findByUid")
            )
    })
    public List findUserAndOrderAll();
}

package com.itcast.mapper;

import com.itcast.domain.Order;
import com.itcast.domain.User;
import org.apache.ibatis.annotations.One;
import org.apache.ibatis.annotations.Result;
import org.apache.ibatis.annotations.Results;
import org.apache.ibatis.annotations.Select;
import org.omg.CORBA.PUBLIC_MEMBER;

import java.util.List;

public interface OrderMapper {
    @Select("select * from orders where uid = #{uid}")
    public List findByUid(int uid);
}

package com.itcast.test;

import com.itcast.domain.User;
import com.itcast.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 MybatisTest3 {
    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);//自动提交事务
        mapper = sqlSession.getMapper(UserMapper.class);
    }

    @Test
    public void testFindAll() {
        List orderList = mapper.findUserAndOrderAll();
        for (User user : orderList) {
            System.out.println(user);
        }
    }
}

3.NvN查询

用户表和角色表的关系为，一个用户有多个角色，一个角色被多个用户使用。

多对多查询的需求：查询用户同时查询出该用户的所有角色。

select * from user;
select * from role r, user_role ur where r.id = ur.role_id and ur.user_id = 用户的id

（1）配置方式：

package com.itcast.mapper;

import com.itcast.domain.User;
import org.apache.ibatis.annotations.*;

import java.util.List;

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

package com.itcast.mapper;

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

import java.util.List;

public interface RoleMapper {
    @Select("select * from role r, user_role ur where r.id = ur.role_id and ur.user_id = #{uid}")
    public List findByUid(int uid);
}

（2）程序演示：

package com.itcast.domain;

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

public class User {
    private int id;
    private String username;
    private String password;
    private Date birthday;
    private List roleList;//当前用户具有的角色

    public List getRoleList() {
        return roleList;
    }

    public void setRoleList(List roleList) {
        this.roleList = roleList;
    }

    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;
    }

    public Date getBirthday() {
        return birthday;
    }

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

    @Override
    public String toString() {
        return "User{" +
                "id=" + id +
                ", username='" + username + ''' +
                ", password='" + password + ''' +
                ", birthday=" + birthday +
                ", roleList=" + roleList +
                '}';
    }
}

package com.itcast.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.itcast.mapper;

import com.itcast.domain.User;
import org.apache.ibatis.annotations.*;

import java.util.List;

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

package com.itcast.mapper;

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

import java.util.List;

public interface RoleMapper {
    @Select("select * from role r, user_role ur where r.id = ur.role_id and ur.user_id = #{uid}")
    public List findByUid(int uid);
}

package com.itcast.test;

import com.itcast.domain.User;
import com.itcast.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);//自动提交事务
        mapper = sqlSession.getMapper(UserMapper.class);
    }

    @Test
    public void testfindAll() {
        List userAndRoleAll = mapper.findUserAndRoleAll();
        for (User user : userAndRoleAll) {
            System.out.println(user);
        }
    }
}