MyBatis - 1 - Helloworld（快速搭建 MyBatis+maven） 、歸檔

• MyBatis SqlSessionFactory的幾種常見創建方式 - https://www.cnblogs.com/doudou-taste/p/9020816.html

---

快速搭建 MyBatis

1. Maven

    <dependency>
               <groupId>mysql</groupId>
               <artifactId>mysql-connector-java</artifactId>
               <version> RELEASE</version>
           </dependency>
   
           <dependency>
               <groupId>org.mybatis</groupId>
               <artifactId>mybatis</artifactId>
               <version>3.2.8</version>
           </dependency>
   　　　　　<!--日誌約束-->
           <dependency>
               <groupId>org.slf4j</groupId>
               <artifactId>slf4j-log4j12</artifactId>
               <version> RELEASE</version>
           </dependency>
   

2. mybatis-config.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>
       <!--配置別名-->
       <typeAliases>
           <package name="com.sf.wj.domain"/>
       </typeAliases>
       <!--數據源配置-->
       <environments default="development">
           <environment id="development">
               <transactionManager type="JDBC"></transactionManager>
               <dataSource type="POOLED">
                   <property name="driver" value="com.mysql.cj.jdbc.Driver"/>
                   <property name="url" value="jdbc:mysql://localhost:3306/company?serverTimezone=UTC"/>
                   <property name="username" value="root"/>
                   <property name="password" value="123456"/>
               </dataSource>
           </environment>
       </environments>
       
       <!--資源引用-->
       <mappers>
           <mapper resource="mappers/UserMapper.xml"/>
       </mappers>
   
   </configuration>
   

3. 【測試類 - 部分】根據 xml 配置文件（全局配置文件） 創建一個 SqlSessionFactory 對象

   package com.sf.wj;
   
   import com.sf.wj.domain.User;
   import com.sf.wj.mapper.UserMapper;
   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.List;
   
   public class UserTest {
       private UserMapper mapper;
       private SqlSession sqlSession;
       private InputStream inputStream;
       @Before
       public void setUp() throws IOException {
           String rusource = "mybatis-config.xml";
            inputStream = Resources.getResourceAsStream(rusource);
           SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);
           //默認傳入參數false，不自動提交
           sqlSession = factory.openSession(false); // 2、獲取sqlSession實例，能直接執行已經映射的 sql 語句
           mapper = sqlSession.getMapper(UserMapper.class);
       }
   
      
   

4. 創建 mapper 映射

   <?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.sf.wj.mapper.UserMapper"><!-- namespace：名稱空間 -->
       <select id="queryById" parameterType="int" resultType="User"><!--id：唯一表示、resultType：返回值類型-->
           select * from user where id = #{id}<!--#{id}接口從傳遞過來的參數-->
       </select>
   
       <delete id="deleteById" parameterType="Integer" >
           delete from user where id = #{id}
       </delete>
   
       <select id="queryAll" resultType="User">
           select * from user
       </select>
   
       <update id="updateUser" parameterType="User">
           update user set username = #{username},password = #{password} where id=#{id}
       </update>
   
       <insert id="insertUser" parameterType="User">
           insert into user (id,username,password) values (#{id},#{username},#{password})
       </insert>
   　　
   　　<!--按多個id查找用戶 foreach-->
   　　<select id="queryByIds" resultType="User">
     　　  select * from user where id in
      　　 <foreach collection="array" open="(" close=")" separator="," item="id">
           #{id}
       　　</foreach>
   　　</select>
   </mapper>
   

5. 創建 mapper 接口

   package com.sf.wj.mapper;
   
   import com.sf.wj.domain.User;
   
   import java.util.List;
   
   public interface UserMapper {
       User queryById(int id);
       void deleteById(int id);
       List<User> queryAll();
       void  updateUser(User user);
       void insertUser(User user);
       List<User> queryByIds(int[] ids);
   }
   
   

6. 補完測試類

   package com.sf.wj;
   
   import com.sf.wj.domain.User;
   import com.sf.wj.mapper.UserMapper;
   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.List;
   
   public class UserTest {
       private UserMapper mapper;
       private SqlSession sqlSession;
       private InputStream inputStream;
       @Before
       public void setUp() throws IOException {
           String rusource = "mybatis-config.xml";
            inputStream = Resources.getResourceAsStream(rusource);
           SqlSessionFactory factory = new SqlSessionFactoryBuilder().build(inputStream);
           //默認傳入參數false，不自動提交
           sqlSession = factory.openSession(false); // 2、獲取sqlSession實例，能直接執行已經映射的 sql 語句
           mapper = sqlSession.getMapper(UserMapper.class);
       }
   
       @After
       public void commit(){
           try {
               sqlSession.commit();
               inputStream.close();
               sqlSession.close();
           } catch (IOException e) {
               e.printStackTrace();
           }
       }
   
       @Test
       public void queryByIdTest(){
           User user = mapper.queryById(1);
           System.out.println(user);
       }
       @Test
       public void queryAllTest(){
           List<User> user = mapper.queryAll();
           System.out.println(user);
       }
       @Test
       public void deleteTest(){
           mapper.deleteById(1);
       }
       @Test
       public void updateTest(){
           User user=new User();
           user.setId(1);
           user.setPassword("qwert");
           user.setUsername("jg");
           mapper.updateUser(user);
       }
   
       @Test
       public void insertTest(){
           User user=new User();
           user.setId(3);
           user.setPassword("369");
           user.setUsername("zs");
           mapper.insertUser(user);
       }
   
   　　//多個id查找
   　　@Test
   　　public void queryByIdsTest(){
      　　 List<User> list = mapper.queryByIds(new int[]{1, 2, 3});
      　　 System.out.println(list);
   　　}
   }
   

技術對比

# JDBC工具？Hibernate？

JDBC工具（Dbutils、jdbcTemplate…）缺點

• sql語句在java 代碼裏面，硬編碼，高耦合
• 缺少整體的解決方案

Hibernate缺點

• 無法優化 sql
• 自定義 sql 需要學習 HQL （但框架旨在消除sql - 與宗旨矛盾）

# Mybatis

• sql 與 java 編碼分離
• sql 開發人員控制

使用 Mybatis ， 只要掌握好 sql 語句

半自動

歷史