MyBatis（12）- mybatis实现 DAO开发

1 查询列表

1.1 DAO

• 接口

package com.tzb.dao;
import com.tzb.domain.User;
import java.util.List;

public interface IUserDao {
    List<User> findAll();

    void saveUser(User user);

    void updateUser(User user);

    void deleteUser(Integer userId);

    User findById(Integer userId);

    // 模糊查询
    List<User> findbyName(String username);

    /**
     * 查询总的用户数
     * @return
     */
    int findTotal();


}

• IUserDao.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.tzb.dao.IUserDao">

    <!--配置查询所有-->
    <select id="findAll" resultType="com.tzb.domain.User">
        select * from user
    </select>

    <insert id="saveUser" parameterType="com.tzb.domain.User">
        <!--配置插入数据后,获取插入数据的 id-->
        <selectKey keyProperty="id" keyColumn="id" resultType="int" order="AFTER">
            select last_insert_id();
        </selectKey>
        insert into user(username,address,sex,birthday)
        values (#{username},#{address},#{sex},#{birthday})
    </insert>

    <update id="updateUser" parameterType="com.tzb.domain.User">

        update user
        set
        username=#{username},
        address=#{address},
        sex=#{sex},
        birthday=#{birthday}
        where id=#{id}

    </update>

    <delete id="deleteUser" parameterType="java.lang.Integer">
        delete from user where id=#{userId}
    </delete>

    <select id="findById" parameterType="int" resultType="com.tzb.domain.User">
        select * from user where id=#{userId}
    </select>

    <select id="findbyName" parameterType="String" resultType="com.tzb.domain.User">
       <!-- select * from user where username like #{username}-->
       select * from user where username like '%${value}%'
    </select>

    <select id="findTotal" resultType="int">
        select count(id) from user;
    </select>


</mapper>

---

• 实现类

package com.tzb.dao.impl;

import com.tzb.dao.IUserDao;
import com.tzb.domain.User;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;

import java.util.List;

public class UserDaoImpl implements IUserDao {

    private SqlSessionFactory factory;

    public UserDaoImpl(SqlSessionFactory factory) {
        this.factory = factory;
    }

    @Override
    public List<User> findAll() {
        //1.根据 factory 获取 sqlSession 对象
        SqlSession session = factory.openSession();
        //2.调用SqlSession方法实现查询列表
        // 参数就是获取配置信息的key，配置文件的 namespace + id
        List<User> users = session.selectList("com.tzb.dao.IUserDao.findAll");
        // 3.释放资源
        session.close();
        return users;
    }

    @Override
    public void saveUser(User user) {

    }

    @Override
    public void updateUser(User user) {

    }

    @Override
    public void deleteUser(Integer userId) {

    }

    @Override
    public User findById(Integer userId) {
        return null;
    }

    @Override
    public List<User> findbyName(String username) {
        return null;
    }

    @Override
    public int findTotal() {
        return 0;
    }
}

---

1.2 单元测试

package com.tzb.test;

import com.tzb.dao.IUserDao;
import com.tzb.dao.impl.UserDaoImpl;
import com.tzb.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.IOException;
import java.io.InputStream;
import java.util.Date;
import java.util.List;

public class MyBatisTest2 {

    private InputStream in;
    private IUserDao userDao;

    @Before
    public void init() throws IOException {
        // 1.读取配置文件
        in = Resources.getResourceAsStream("SqlMapConfig.xml");
        //2.创建 SqlSessionFactory 工厂
        SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(in);
        // 3.使用工厂对象创建 到对象
        userDao = new UserDaoImpl(factory);
    }

    @After
    public void destory() throws IOException {
        in.close();
    }

    @Test
    public void testFindAll() throws IOException {
        List<User> users = userDao.findAll();
        for (User user : users) {
            System.out.println(user);
        }
    }

}

2 保存操作

2.1 DAO实现类

 @Override
    public void saveUser(User user) {
        SqlSession session = factory.openSession();
        session.insert("com.tzb.dao.IUserDao.saveUser",user);
        // 提交事务
        session.commit();
        session.close();
    }

---

单元测试

   @Test
    public void testSave() throws IOException {
        User user = new User();
        user.setUsername("钢铁侠");
        user.setAddress("US");
        user.setSex("男");
        user.setBirthday(new Date());

        System.out.println("保存前："+user);
        userDao.saveUser(user);
        System.out.println("保存后："+user);
    }

2.2 执行过程分析