聊聊、Mybatis XML

导航： 

聊聊、Mybatis API 

聊聊、Mybatis集成Spring XML 方式

聊聊、Mybatis集成Spring 注解方式 

聊聊、手写Mybatis XML配置方式  

聊聊、手写Mybatis 注解配置方式   

聊聊、手写Mybatis SpringBoot Starter 

项目结构

---

引入依赖 

---

<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.4.4</version>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.30</version>
</dependency>
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.0.31</version>
</dependency>
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis-spring</artifactId>
<version>1.2.5</version>
</dependency>

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>
<properties resource="datasource-dev.properties"></properties>
<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="${username}"/>
<property name="password" value="${password}"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="mappers/AccountMapper.xml"/>
<mapper class="org.rockcode.mappers.AccountMapper" />
</mappers>
</configuration>

AccountMapper.xml 

---

 <!DOCTYPE mapper
PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-mapper.dtd">
<mapper namespace="accountMapper">
<select id="queryAll" resultType="java.util.Map">
select * from account
</select>
</mapper>

AccoutMapper 

---

package org.rockcode.mappers;

import org.apache.ibatis.annotations.Select;
import java.util.List;
import java.util.Map;

public interface AccountMapper {
@Select("select * from account")
public List<Map<String,Object>> queryAll();
}

datasource-dev.properties

---

driver = com.mysql.jdbc.Driver
url = jdbc:mysql://127.0.0.1:3306/test?useSSL=false
username = root
password = root

Main方法 

---

public static void main(String[] args) {

String source = "mybatis-config.xml";
try {
InputStream in = Resources.getResourceAsStream(source);
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in);
SqlSession sqlSession = sqlSessionFactory.openSession();
List<Object> list = sqlSession.selectList("accountMapper.queryAll");
System.out.println(list);
System.out.println("====================================");
AccountMapper mapper = sqlSession.getMapper(AccountMapper.class);
List<Map<String, Object>> mapList = mapper.queryAll();
System.out.println(mapList);
} catch (IOException e) {
e.printStackTrace();
}

}

上面就是 xml 相关的代码，在 mybatis-config.xml 配置了下面这行：

<mappers>

  <mapper resource="mappers/AccountMapper.xml"/>

  <mapper class="org.rockcode.mappers.AccountMapper" />

</mappers>

mybatis 中总共有 4 种配置方式，resource、class、url、package。其中，class 和 package 会走代理逻辑。而 resource 和 url 不会走代理逻辑。这个后面会详细写到。

AccountMapper mapper = sqlSession.getMapper(AccountMapper.class) 对应 class 配置，也就是走 jdk动态代理。

List<Object> list = sqlSession.selectList("accountMapper.queryAll") 对应 resource 配置，直接 AccountMapper.xml 里面获取 sql 执行逻辑，不会走动态代理。

但是像 class、resource、url 配置不够灵活，如果有多个配置，则要写很多。 

<mappers>

  <mapper resource="mappers/AccountMapper.xml"/>

  <mapper resource="mappers/AMapper.xml"/>

  <mapper resource="mappers/BMapper.xml"/>

  <mapper class="org.rockcode.mappers.AccountMapper" />

 <mapper class="org.rockcode.mappers.AMapper" />

 <mapper class="org.rockcode.mappers.BMapper" />

</mappers>

这个时候就可以用 package，<package name="org.rockcode.mappers"/>，则 org.rockcode.mappers 包下面的 Mapper 接口，都会处理。不用全部写在配置文件中。

xml 的配置就到这里了，下一篇会聊聊 mybatis 如何与 spring 集成的呢？用到了 spring 哪些扩展点呢？