Mybatis學習筆記（一）

小小白一枚，第一次寫博客，我那可憐的記憶力兒，不整理一下不行了。

只是非常基礎的知識，方便自己的回顧，大神請繞道。

一、關於MyBatis整體架構

此圖片參考slow_Wakler的博客

二、關於mybatis的使用步驟

官網云云，MyBatis是支持定製化SQL，存儲過程以及高級映射的優秀持久層框架。

1、首先嘍，全局配置：mybatis-config.xml等同於hibernate的 hibernate-cfg.xml

    作用：配置數據源，引入映射文件

<?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>
	<environments default="development">
		<environment id="development">
			<transactionManager type="JDBC"/>
			<dataSource type="POOLED">
				<property name="driver" value="com.mysql.jdbc.Driver"/>
				<property name="url" value="jdbc:mysql://127.0.0.1:3306/mybatis"/>
				<property name="username" value="root"/>
				<property name="password" value="123"/>
			</dataSource>
		</environment>
	</environments>
	<mappers>
		<mapper resource="UserMapper.xml"/>
	</mappers>
</configuration>

2、 映射文件：xxmapper.xml等同於hibernate 的 xx.hbm.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="UserMapper">
	<select id="queryUserById" resultType="cn.zgg.mybatis.pojo.User">
		select * from tb_user where id=#{id}
	</select>
</mapper>

3、SqlSessionFactory:通過newSqlSessionFactoryBuilder().build(inputStream)來構建,inputStream：讀取配置文件的IO流

    作用：獲取SqlSession

4、SqlSession:    執行CRUD操作

5、調用session.commit()執行提交操作

6、調用session.close()關閉會話

Executor:SqlSession通過調用它完成具體的CRUD操作，這是一個接口，提供了兩種實現：緩存和數據庫的實現

Mapped: 具體的SQL，參數類型和結果封裝類型，主要有：hashmap,基本數據類型，pojo

官網裏有詳細API：mybatis官網

二、mybatis完整的CRUD

1、UserDao接口的方法

import cn.zgg.mybatis.pojo.User;

public interface UserDao {
	/*
	 * 查詢用戶
	 */
	public User queryUserById(Long id);
	/*
	 * 新增用戶
	 */
	public void insertUser(User user);
	/*
	 * 刪除用戶
	 */
	public void deleteUserById(Long id);
	/*
	 * 修改用戶
	 */
	public void updateUser(User user);
	/*
	 * 查詢所有用戶
	 */
	public List<User> queryUserAll();

}

2、UserDaoImpl實現類

package cn.zgg.mybatis.dao.impl;

import java.util.List;

import org.apache.ibatis.session.SqlSession;

import cn.zgg.mybatis.dao.UserDao;
import cn.zgg.mybatis.pojo.User;

public class UserDaoImpl implements UserDao{
	
	private SqlSession sqlSession;
	
	public UserDaoImpl(SqlSession sqlSession){
		this.sqlSession=sqlSession;
	}
	@Override
	public User queryUserById(Long id) {
		return this.sqlSession.selectOne("UserDaoMapper.queryUserById", id);
	}
	@Override
	public void insertUser(User user) {
		this.sqlSession.insert("UserDaoMapper.insertUser", user);
		this.sqlSession.commit();
	}
	@Override
	public void deleteUserById(Long id) {
		this.sqlSession.update("UserDaoMapper.deleteUserById", id);
		this.sqlSession.commit();
	}
	@Override
	public void updateUser(User user) {
		this.sqlSession.update("UserDaoMapper.updateUser", user);
		this.sqlSession.commit();
	}
	@Override
	public List<User> queryUserAll() {
		return this.sqlSession.selectList("UserDaoMapper.queryUserAll");
	}

}

3、UserDaoMapper.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="UserDaoMapper">
	<select id="queryUserById" resultType="cn.zgg.mybatis.pojo.User">
		select * from tb_user where id=#{id}
	</select>
	
	<select id="queryUserAll" resultType="cn.zgg.mybatis.pojo.User">
		select * from tb_user
	</select>
	
	<insert id="insertUser" parameterType="cn.zgg.mybatis.pojo.User">
		INSERT INTO tb_user(
			user_name,
			password,
			name,
			age,
			sex,
			birthday,
			created,
			updated
			
		)VALUES(
			#{userName},
			#{password},
			#{name},
			#{age},
			#{sex},
			#{birthday},
			NOW(),
			NOW()
			
		);
	</insert>
	
	<update id="updateUser" parameterType="cn.zgg.mybatis.pojo.User">
		UPDATE tb_user 
		SET 
		user_name=#{userName},
		password=#{password},
		name=#{name},
		age=#{age},
		sex=#{sex},
		birthday=#{birthday},
		updated=NOW()
		WHERE
		(id=#{id});
	</update>
	
	<delete id="deleteUserById" parameterType="java.lang.Long">
		delete  from tb_user where id=#{id}
	</delete>
</mapper>

4、在mybatis-config.xml中引入mapper配置文件

<mappers>
		<mapper resource="UserMapper.xml"/>
		<mapper resource="UserDaoMapper.xml"/>
	</mappers>

5、新建測試用例

UserDao右擊，新建test,勾選setup,即可

package cn.zgg.mybatis.dao;
import java.io.InputStream;
import java.util.List;
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 cn.zgg.mybatis.dao.impl.UserDaoImpl;
import cn.zgg.mybatis.pojo.User;

public class UserDaoTest {
	private UserDao userDao;
	@Before
	public void setUp() throws Exception {
		String resource="mybatis-config.xml";
		//讀取配置文件
		InputStream inputStream = Resources.getResourceAsStream(resource);
		//構建sqlSessionFactory
		SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
		//打開sqlSession
		SqlSession sqlSession = sqlSessionFactory.openSession();
		//初始化userDAO
		//UserDao userDao=new UserDaoImpl(sqlSession);
		this.userDao=new UserDaoImpl(sqlSession);
	}

	@Test
	public void testQueryUserById() {
		User user = this.userDao.queryUserById(1l);
		System.out.println(user);
	}

	@Test
	public void testInsertUser() {
		User user = new User();
		user.setAge(18);
		user.setName("zgg");
		user.setSex(1);
		this.userDao.insertUser(user);
	}

	@Test
	public void testDeleteUserById() {
		this.userDao.deleteUserById(5l);
		
	}

	@Test
	public void testUpdateUser() {
		User user = this.userDao.queryUserById(1l);
		user.setAge(12);
		user.setName("wyll");
		this.userDao.updateUser(user);
	}

	@Test
	public void testQueryUserAll() {
		List<User> list = this.userDao.queryUserAll();
		for (User user : list) {
			System.out.println(user);
		}
	}

}

三、總結

我創建的是maven工程，麻煩童鞋自行導入依賴和相關配置文件。

 <dependencies>
  	<dependency>
			<groupId>mysql</groupId>
			<artifactId>mysql-connector-java</artifactId>
		</dependency>

  	<dependency>
  		<groupId>org.mybatis</groupId>
  		<artifactId>mybatis</artifactId>
  	</dependency>

  	<dependency>
  		<groupId>org.slf4j</groupId>
  		<artifactId>slf4j-log4j12</artifactId>
  	</dependency>

  	<dependency>
  		<groupId>junit</groupId>
  		<artifactId>junit</artifactId>
  		<scope>test</scope>
  	</dependency>
  </dependencies>

四、下一篇是parameterType的總結