Mybatis的xml+接口方式实现crud功能

1. User.java

package com.qfedu.pojo;

import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
public class User {

    private int uid;
    private String username;
    private String password;
    private int age;
    private String addr;
}

2.IUserDao.java

import com.qfedu.pojo.User;

import java.util.List;

public interface IUserDao {

    /**
     *  查询所有的User对象
     * @return User对象的列表
     */
    List<User> getAllUsers();

    /**
     * 新增一个User对象
     * @param u 要新增的用户对象
     * @return 受影响的行数
     */
    int saveUser(User u);
}

3.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">

<!--
    第二种实现mybatis的方式为：接口+xml方式
    这种方式有特别的要求
        1.  namespace必须是接口的全路径
        2.  每个节点的id必须是接口中的方法名
        3.  该接口中的方法不允许重载，否则namespace+id将不唯一
        4.  注意该接口中的增删改的方法的返回值，最好使用int
-->
<mapper namespace="com.qfedu.dao.IUserDao">
    
    <!--
        ID为接口中的方法名
    -->
    <select id="getAllUsers" resultType="User">
      select * from user
    </select>

    <insert id="saveUser" >
        insert into user values(null, #{username}, #{password}, #{age}, #{addr})
    </insert>

    <update id="updateUser">
        update user set username = #{username}, password =#{password}, age=#{age}, addr = #{addr} where uid = #{uid}
    </update>
</mapper>

4.SessionUtils.java

package com.qfedu.util;

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 java.io.IOException;

public class SessionUtils {

    private static SqlSession mSession = null;
    private static SqlSessionFactory mFactory = null;

    static {
        try {
            mFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsStream("mybatis.xml"));
        } catch (IOException e) {
            e.printStackTrace();
        }
    }


    /**
     * 获取SqlSession对象
     * @return
     */
    public static SqlSession getSession(){

        mSession = mFactory.openSession(true);

        return mSession;
    }

    /**
     * 关闭SqlSession对象
     * @param session 要关闭的SqlSession对象
     */
    public static void closeSession(SqlSession session){
        if(session != null){
            session.close();
            session = null;
        }
    }
}

5.Mybatis.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">

<!--
    该配置文件中包含一个configuration节点
        里面有配置信息 分别是环境和映射
        　其中环境里有datasource，里面有我们熟悉的连接数据库的四个字符串
-->
<configuration>

    <!--
        引入db的配置文件信息，后面用到的四个连接字符串就可以直接使用 ${}的方式来动态引入
    -->
    <properties resource="db.properties">
    </properties>

    <!--
        给当前mybatis项目添加日志功能，该STDOUT_LOGGING值的好处是不用添加第三方jar包就可以有日志的输出
    -->
    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING"/>
    </settings>

    <typeAliases>
        <!--<typeAlias type="com.qfedu.pojo.Order" alias="abc" />-->
        <package name="com.qfedu.pojo" />
    </typeAliases>

    <environments default="development">
        <environment id="development">
            <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
                <property name="driver" value="${driver}"/>
                <property name="url" value="${url}"/>
                <property name="username" value="${user}"/>
                <property name="password" value="${pass}"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="com/qfedu/dao/UserMapper.xml"/>
    </mappers>
</configuration>

6.TestUser.java

package com.qfedu.pojo;

import org.junit.Test;

public class TestUser {

    @Test
    public void testUser(){

        User u = new User();

        u.setUid(1);
        u.setUsername("chenggang");
        u.setPassword("888888");
        u.setAddr("shenzhen");
        u.setAge(18);

        System.out.println(u);
    }
}

7.TestUserDao.java

import com.qfedu.dao.IUserDao;
import com.qfedu.util.SessionUtils;
import org.apache.ibatis.session.SqlSession;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

import java.util.List;

public class TestUserDao {

    private SqlSession session = null;

    @Before
    public void setUp(){

        session = SessionUtils.getSession();
    }

    @After
    public void tearDown(){
        SessionUtils.closeSession(session);
    }

    @Test
    public void testGetAllUsers(){
        IUserDao mapper = session.getMapper(IUserDao.class);

        List<User> users = mapper.getAllUsers();

        for (User u : users) {
            System.out.println(u);
        }
    }

    @Test
    public void testSaveUser(){
        IUserDao userDao = session.getMapper(IUserDao.class);

        User u = new User(17, "liuchang", "888888", 20, "guangzhou");
        int result = userDao.saveUser(u);
        System.out.println(result);
    }
}