1 mybatis的多表查询

（16）Mybatis - mybatis的多表查询,准备工作和代码

MySQL中

Account
User

mysql中加入:

DROP TABLE IF EXISTS `account`;

CREATE TABLE `account`(
`ID` int(11) NOT NULL COMMENT '编号',
`UID` int(11) default NULL COMMENT '用户编号',
`MONEY` double default NULL COMMENT '金额',
PRIMARY KEY (`ID`),
KEY `FK_Reference_8` (`UID`),
CONSTRAINT `FK_Reference_8` FOREIGN KEY (`UID`) REFERENCES `user` (`id`)
)ENGINE=InnoDB DEFAULT CHARSET=utf8;

insert into `account` (`ID`,`UID`,`MONEY`) values (1,46,1000),(2,45,1000),(3,46,2000);

（16）Mybatis - mybatis的多表查询,准备工作和代码

AccountDao

package com.dao;

import com.domain.Account;

import java.util.List;

public interface AccountDao {


    /**
     * 查询所有
     * @return
     */
    List<Account> findAll();
}

UserDao

package com.dao;

import com.domain.User;

import java.util.List;

/**
 * 用户的持久层
 */
public interface UserDao {

    /**
     * 查询所有的用户
     */
    List<User> findAll();

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


}

Account

package com.domain;

import java.io.Serializable;

public class Account implements Serializable {

    private Integer id;
    private Integer uid;
    private Double money;

    public Integer getId() {
        return id;
    }

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

    public Integer getUid() {
        return uid;
    }

    public void setUid(Integer uid) {
        this.uid = uid;
    }

    public Double getMoney() {
        return money;
    }

    public void setMoney(Double money) {
        this.money = money;
    }

    @Override
    public String toString() {
        return "Account{" +
                "id=" + id +
                ", uid=" + uid +
                ", money=" + money +
                '}';
    }
}

User

package com.domain;

import java.io.Serializable;

//让它实现序列化接口
public class User implements Serializable {


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

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

    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 getBirthday() {
        return birthday;
    }

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

    public String getSex() {
        return sex;
    }

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

    public String getAddress() {
        return address;
    }

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

AccountDao.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.AccountDao">
    <!--配置查询所有-->
    <select id="findAll" resultType="Account">
        select * from account;
    </select>

</mapper>

UserDao.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.UserDao">
    <!--配置查询所有-->
    <select id="findAll" resultType="uSeR">
        select * from user;
    </select>

    <!--根据ID查询用户-->
    <select id="findById" parameterType="INT" resultType="user">
        select * from user where id = #{uid};
    </select>



</mapper>

jdbcConfig.properties

jdbc.driver=com.mysql.jdbc.Driver
jdbc.url=jdbc:mysql://localhost:3306/mybatis?characterEncoding=UTF-8
jdbc.username=root
jdbc.password

log4j.properties

log4j.rootCategory=debug, CONSOLE, LOGFILE

log4j.logger.org.apache.axis.enterprise=FATAL, CONSOLE

log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender
log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout
log4j.appender.CONSOLE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30c %x - %m\n

log4j.appender.LOGFILE=org.apache.log4j.FileAppender
log4j.appender.LOGFILE.File=d:\axis.log
log4j.appender.LOGFILE.Append=true
log4j.appender.LOGFILE.layout=org.apache.log4j.PatternLayout
log4j.appender.LOGFILE.layout.ConversionPattern=%d{ISO8601} %-6r [%15.15t] %-5p %30.30C %x - %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">
<!--首先是跟元素-->
<configuration>
    <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 , 选择一个默认的环境mysql-->
    <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 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>

AccountTest

import com.dao.AccountDao;
import com.domain.Account;
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.After;
import org.junit.Before;
import org.junit.Test;

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

public class AccountTest {

    private InputStream in;
    private SqlSession sqlSession;
    private AccountDao accountDao;

    @Before//用于在测试方法之前执行
    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
        accountDao = sqlSession.getMapper(AccountDao.class);
    }

    @After//用于在测试方法之后执行
    public void destory()throws Exception{
        //6.释放资源
        sqlSession.close();
        in.close();
    }

    @Test
    public void testFindAll(){
        List<Account> accounts = accountDao.findAll();

        for(Account account: accounts){
            System.out.println(account);
        }

    }






}

MybaitsTest

import com.dao.UserDao;
import com.domain.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.After;
import org.junit.Before;
import org.junit.Test;

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

public class MybatisTest {


    private InputStream in;
    private SqlSession sqlSession;
    private UserDao userDao;

    @Before//用于在测试方法之前执行
    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(UserDao.class);
    }

    @After//用于在测试方法之后执行
    public void destory()throws Exception{
//        //5.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(){
        //5.执行查询所有方法
        List<User> users = userDao.findAll();
        for(User user: users){
            System.out.println(user);
        }
    }

    /**
     * 测试根据ID查询用户
     */
    @Test
    public void testFindOne(){
        User user = userDao.findById(43);
        System.out.println(user);
    }



}

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com</groupId>
    <artifactId>mybatis2</artifactId>
    <version>1.0-SNAPSHOT</version>


    <dependencies>
        <dependency>
            <groupId>org.mybatis</groupId>
            <artifactId>mybatis</artifactId>
            <version>3.4.6</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.47</version>
        </dependency>

        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>

        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
        </dependency>

    </dependencies>

</project>

（16）Mybatis - mybatis的多表查询,准备工作和代码

1 mybatis的多表查询

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