Mybatis的關聯映射（一對一一對多多對多）

1. MyBatis中的一對一關聯關系

1.1 建立兩個表以及對應的pojo

1.建立人員表(tb_person):

CREATE TABLE tb_person (
	id INT PRIMARY KEY AUTO_INCREMENT,
	NAME VARCHAR ( 32 ),
	age INT,
	sex VARCHAR ( 8 ),
	card_id INT UNIQUE,
FOREIGN KEY ( card_id ) REFERENCES tb_idcard ( id ));
INSERT INTO tb_person(name,age,sex,card_id) VALUES('zhangsan',29,'女',1);
INSERT INTO tb_person(name,age,sex,card_id) VALUES('lisi',29,'男',2)

人員表的Pojo Tb_person：

package beans.pojo;

public class Tb_person {
    private Integer id;
    private String name;
    private Integer age;
    private String sex;
    private Tb_idcard tb_idcard;  //主鍵所在類的對象

    public Integer getId() {
        return id;
    }

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

    public Tb_person() {
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }


    public Tb_idcard getTb_idcard() {
        return tb_idcard;
    }

    public void setTb_idcard(Tb_idcard tb_idcard) {
        this.tb_idcard = tb_idcard;
    }

    @Override
    public String toString() {
        return "Tb_person{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", sex='" + sex + '\'' +
                ", tb_idcard=" + tb_idcard +
                '}';
    }
}

2.建立身份證表(tb_idcard):

CREATE TABLE tb_idcard (
	id INT PRIMARY KEY AUTO_INCREMENT,
	sfzh VARCHAR ( 18 ),
    bfjg VARCHAR ( 50 ));
INSERT INTO tb_idcard(sfzh,bfjg) VALUES('1234567894561333','東昌府警察局');
INSERT INTO tb_idcard(sfzh,bfjg) VALUES('5548465132151845','東昌府警察局');

人員表的Pojo Tb_idcard：

package beans.pojo;

public class Tb_idcard {
    private Integer id;
    private String  sfzh;
    private String bfjg;

    public Integer getId() {
        return id;
    }

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

    public String getSfzh() {
        return sfzh;
    }

    public void setSfzh(String sfzh) {
        this.sfzh = sfzh;
    }

    public String getBfjg() {
        return bfjg;
    }

    public void setBfjg(String bfjg) {
        this.bfjg = bfjg;
    }

    @Override
    public String toString() {
        return "Tb_idcard{" +
                "id=" + id +
                ", sfzh='" + sfzh + '\'' +
                ", bfjg='" + bfjg + '\'' +
                '}';
    }
}

1.2 配置資料庫相應的檔案

jdbc.properties：

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

log4j.properties

# Global logging configuration，建議開發環境中要用debug
log4j.rootLogger=DEBUG, stdout
# Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

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>
    <!--    核心配置檔案-->
    <properties resource="jdbc.properties"></properties>
    <!--配置類型别名-->
    <typeAliases>
        <package name="beans.pojo"/>
    </typeAliases>
    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"></transactionManager>
            <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="beans.bao"></package>
    </mappers>
</configuration>

1.3 建立UserMapper接口

public interface UserMapper {
    List<Tb_person> findAll();
}

1.4 建立映射檔案UserMapper.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">

<!-- parameterType 輸入映射
     resultType 和 resultMap 完成輸出映射-->
<!-- 與接口相關聯-->
<mapper namespace="beans.bao.OrdersMapper">
    <resultMap id="findP_C" type="beans.pojo.Tb_person">
        <!-- id:你傳回的主鍵-->
        <!-- column: 指定表中對應的字段-->
        <!-- property： 指定映射到的實體類對象屬性-->
        <id column="id" property="id"></id>
        <result column="name" property="name"></result>
        <result column="age" property="age"></result>
        <result column="sex" property="sex"></result>
         <!--注意 :javaType 指定映射到實體對象屬性的類型 -->
        <association property="tb_idcard" javaType="beans.pojo.Tb_idcard">
            <id column="card_id" property="id"></id>
            <result column="sfzh" property="sfzh"></result>
            <result column="bfjg" property="bfjg"></result>
        </association>
    </resultMap>
    <select id="findAll" resultMap="findP_C">
SELECT
   tp.`name`,
   tp.age,
   tp.sex,
   ti.id,
   ti.sfzh,
   ti.bfjg
FROM
   tb_person tp,
   tb_idcard ti
WHERE
   tp.card_id = ti.id
    </select>
</mapper>

測試（注意兩個注解）

public class Test1 {
    InputStream inputStream;
    SqlSessionFactory sqlSessionFactory;
    @Before
    public void before() {
        try {
            inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
            sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
    @Test
    public void test(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        UserMapper mapper = sqlSession.getMapper(UserMapper.class);
        List<Tb_person> tb_personList = mapper.findAll();
        for (Tb_person tb_person : tb_personList) {
            System.out.println(tb_person);
        }
        sqlSession.close();
    }
}

Mybatis的關聯映射（一對一一對多多對多）

2.MyBatis中的一對多關聯關系

關于資料庫的配置我在這裡就不在寫了

2.1 建立表以及表的pojo

1.建立使用者表(tb_user)

CREATE TABLE tb_user(
    id INT(32) PRIMARY KEY AUTO_INCREMENT,
    username VARCHAR(32),
    address VARCHAR(256)
);
INSERT INTO tb_user
VALUES
	( 1, '張三', '山東聊城' );
INSERT INTO tb_user
VALUES
	( 2, '李四', '山東濟南' );
INSERT INTO tb_user
VALUES
	( 3, '王五', '山東青島' );

package beans.pojo;

import java.util.List;

public class Tb_user {
    private Integer id;
    private String username;
    private String address;
    private List<Tb_orders> tb_ordersList;

    public Tb_user() {
    }

    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 List<Tb_orders> getTb_ordersList() {
        return tb_ordersList;
    }

    public void setTb_ordersList(List<Tb_orders> tb_ordersList) {
        this.tb_ordersList = tb_ordersList;
    }

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

    @Override
    public String toString() {
        return "Tb_user{" +
                "id=" + id +
                ", username='" + username + '\'' +
                ", address='" + address + '\'' +
                ", tb_ordersList=" + tb_ordersList +
                '}';
    }
}

2.建立訂單表(tb_orders)

CREATE TABLE tb_orders (
	id INT ( 32 ) PRIMARY KEY AUTO_INCREMENT,
	number VARCHAR ( 32 ) NOT NULL,
	user_id INT ( 32 ) NOT NULL,
FOREIGN KEY ( user_id ) REFERENCES tb_user ( id ));
INSERT INTO tb_orders VALUES(1,'20190402001',1);
INSERT INTO tb_orders VALUES(2,'20190402002',2);
INSERT INTO tb_orders VALUES(3,'20190402003',1);

package beans.pojo;

import java.util.List;

public class Tb_orders {
    private Integer id;
    private String number;


    public Tb_orders() {
    }

    public Integer getId() {
        return id;
    }

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

    public String getNumber() {
        return number;
    }

    public void setNumber(String number) {
        this.number = number;
    }


    @Override
    public String toString() {
        return "Tb_orders{" +
                "id=" + id +
                ", number='" + number + '\'' +
                '}';
    }
}

中間表（tid 教師ID sid 學生的ID）

Mybatis的關聯映射（一對一一對多多對多）

2.2 建立OrdersMapper接口

public interface OrdersMapper {
    List<Tb_user> findAll();
}

2.3 建立映射檔案OrdersMapper.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">

<!-- parameterType 輸入映射
     resultType 和 resultMap 完成輸出映射-->
<!-- 與接口相關聯-->
<mapper namespace="beans.bao.OrdersMapper">

    <resultMap id="findU_O" type="beans.pojo.Tb_user">
        <id column="id" property="id"></id>
        <result column="username" property="username"></result>
        <result column="address" property="address"></result>
        <collection property="tb_ordersList" ofType="beans.pojo.Tb_orders">
            <id column="user_id" property="id"></id>
            <result column="number" property="number"></result>
        </collection>
    </resultMap>

   <select id="findAll" resultMap="findU_O">
SELECT
   tu.id,
   tu.username,
   tu.address,
   tbo.number
FROM
   tb_user tu,
   tb_orders tbo
WHERE
   tu.id = tbo.user_id
   </select>
</mapper>

測試

package beans.test;



import beans.bao.OrdersMapper;
import beans.pojo.Tb_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.Before;
import org.junit.Test;

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


public class Test1 {
    InputStream inputStream;
    SqlSessionFactory sessionFactory;
    @Before
    public void before() {
        try {
             inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
             sessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
    @Test
    public void test(){
        SqlSession sqlSession = sessionFactory.openSession();
        OrdersMapper mapper = sqlSession.getMapper(OrdersMapper.class);
        List<Tb_user> tb_userList = mapper.findAll();
        for (Tb_user tb_user : tb_userList) {
            System.out.println(tb_user);
        }
        sqlSession.close();
    }
}

Mybatis的關聯映射（一對一一對多多對多）

3. MyBatis中的多對多關聯關系

多對多就是兩個一對多，隻是多了一個中間表，查詢時隻需内連接配接一下中間表即可，其他沒有變化

3.1建立表以及對應的Pojo

教師表（tb_teacher）

CREATE TABLE tb_teacher(
id int(32) PRIMARY KEY AUTO_INCREMENT,
tname VARCHAR(16) NOT NULL
);

insert into tb_teacher values (1,'淫老師');
insert into tb_teacher values (2,'當老師');
insert into tb_teacher values (3,'季老師');
insert into tb_teacher values (4,'巴老師');

package com.pojo;


import java.util.List;

public class Tb_teacher {
    private Integer id;
    private String tname;
    private List<Tb_student> studentList;

    public Integer getId() {
        return id;
    }

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

    public String getTname() {
        return tname;
    }

    public void setTname(String tname) {
        this.tname = tname;
    }

    public List<Tb_student> getStudentList() {
        return studentList;
    }

    public void setStudentList(List<Tb_student> studentList) {
        this.studentList = studentList;
    }

    @Override
    public String toString() {
        return "Tb_teacher{" +
                "id=" + id +
                ", tname='" + tname + '\'' +
                '}';
    }
}

學生表(tb_student)

DROP TABLE IF EXISTS `tb_student`;
CREATE TABLE `tb_student`  (
  `id` int(32) NOT NULL AUTO_INCREMENT,
  `name` varchar(12) CHARACTER SET utf8 COLLATE utf8_general_ci NOT NULL,
  `age` int(255) NULL DEFAULT NULL,
  PRIMARY KEY (`id`) USING BTREE
);

INSERT INTO `tb_student` VALUES (1, '小粉', 15);
INSERT INTO `tb_student` VALUES (2, '小紫', 16);
INSERT INTO `tb_student` VALUES (3, '小花', 17);
INSERT INTO `tb_student` VALUES (4, '小紅', 13);
INSERT INTO `tb_student` VALUES (5, '小白', 12);
INSERT INTO `tb_student` VALUES (6, '小黑', 10);
INSERT INTO `tb_student` VALUES (7, '小綠', 18);

package com.pojo;


import java.util.List;

public class Tb_student {
    private Integer id;
    private String name;
    private Integer age;
    private List<Tb_teacher> teacherList;

    public Integer getId() {
        return id;
    }

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

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public List<Tb_teacher> getTeacherList() {
        return teacherList;
    }

    public void setTeacherList(List<Tb_teacher> teacherList) {
        this.teacherList = teacherList;
    }

    @Override
    public String toString() {
        return "Tb_student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", teacherList=" + teacherList +
                '}';
    }
}

3.2 建立Usermapper接口

public interface Usermapper {
    List<Tb_student> findAll();
}

3.3 建立映射檔案Usermapper.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.dao.Usermapper">

    <resultMap id="student_teacher" type="com.pojo.Tb_student">
        <id column="id" property="id"></id>
        <result column="name" property="name"></result>
        <result column="age" property="age"></result>
        <collection property="teacherList" ofType="com.pojo.Tb_teacher">
            <!--注意 column 是你的中間表裡教師對應的字段-->
            <id column="tid" property="id"></id>
            <result column="tname" property="tname"></result>
        </collection>
    </resultMap>

    <select id="findAll" resultMap="student_teacher">
SELECT
    ts.id,
   ts.`name`,
   ts.age,
   tt.id,
   tt.tname
FROM
   tb_student ts,
   tb_teacher tt,
   student_teacher st
WHERE
   ts.id = st.sid
   AND tt.id = st.tid
    </select>
</mapper>

測試

package com.test;

import com.dao.Usermapper;
import com.pojo.Tb_student;
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 UserTest {
    InputStream inputStream;
    SqlSessionFactory sqlSessionFactory;
    @Before
    public void before(){
        try {
             inputStream = Resources.getResourceAsStream("SqlMapConfig.xml");
             sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    @Test
    public void test1(){
        SqlSession sqlSession = sqlSessionFactory.openSession();
        Usermapper mapper = sqlSession.getMapper(Usermapper.class);
        List<Tb_student> tbStudentList = mapper.findAll();
        for (Tb_student tb_student : tbStudentList) {
            System.out.println(tb_student);
        }
        sqlSession.close();
    }
}

Mybatis的關聯映射（一對一一對多多對多）

Mybatis的關聯映射（一對一一對多多對多）

1. MyBatis中的一對一關聯關系

1.1 建立兩個表以及對應的pojo

1.2 配置資料庫相應的檔案

jdbc.properties：

log4j.properties

SqlMapConfig.xml

1.3 建立UserMapper接口

1.4 建立映射檔案UserMapper.xml

測試（注意兩個注解）

2.MyBatis中的一對多關聯關系

2.1 建立表以及表的pojo

2.2 建立OrdersMapper接口

2.3 建立映射檔案OrdersMapper.xml

測試

3. MyBatis中的多對多關聯關系

3.1建立表以及對應的Pojo

3.2 建立Usermapper接口

3.3 建立映射檔案Usermapper.xml

測試

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Mybatis的關聯映射（一對一 一對多 多對多）

1. MyBatis中的一對一關聯關系

1.1 建立兩個表以及對應的pojo

1.2 配置 資料庫相應的檔案

jdbc.properties：

log4j.properties

SqlMapConfig.xml

1.3 建立UserMapper接口

1.4 建立映射檔案UserMapper.xml

測試（注意 兩個注解）

2.MyBatis中的一對多關聯關系

2.1 建立表 以及表的pojo

2.2 建立OrdersMapper接口

2.3 建立映射檔案OrdersMapper.xml

測試

3. MyBatis中的多對多關聯關系

3.1建立表 以及對應的Pojo

3.2 建立Usermapper接口

3.3 建立映射檔案Usermapper.xml

測試

繼續閱讀

Mybatis的關聯映射（一對一一對多多對多）

1.2 配置資料庫相應的檔案

測試（注意兩個注解）

2.1 建立表以及表的pojo

3.1建立表以及對應的Pojo