读源码肯定要debug,先搭好环境。首先把源码下载到本地: https://github.com/mybatis/mybatis-3 可以用git也可以直接下载zip包。下载完后我们需要的是src目录和pom.xml文件,准备完毕
1:创建一个java工程:
2:把mybatis源码的org文件(位置:src->main->java)复制到新建工程的main目录下,把mybatis源码的pom.xml里面的dependency复制到工程的pom.xml的dependencies中。顺便在dependency加上mysql驱动,修改maven-compile-plugin为1.8,下图附上dependencies和build
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>com.hhg.jerry</groupId>
<artifactId>mybatis-gg</artifactId>
<version>1.0-SNAPSHOT</version>
<name>mybatis-gg</name>
<dependencies>
<dependency>
<groupId>ognl</groupId>
<artifactId>ognl</artifactId>
<version>3.2.6</version>
<scope>compile</scope>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.javassist</groupId>
<artifactId>javassist</artifactId>
<version>3.22.0-GA</version>
<scope>compile</scope>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>1.7.25</version>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>1.7.25</version>
<optional>true</optional>
</dependency>
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
<optional>true</optional>
</dependency>
<dependency>
<groupId>org.apache.logging.log4j</groupId>
<artifactId>log4j-core</artifactId>
<version>2.11.0</version>
<optional>true</optional>
</dependency>
<dependency>
<groupId>commons-logging</groupId>
<artifactId>commons-logging</artifactId>
<version>1.2</version>
<optional>true</optional>
</dependency>
<dependency>
<groupId>cglib</groupId>
<artifactId>cglib</artifactId>
<version>3.2.6</version>
<optional>true</optional>
</dependency>
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.38</version>
</dependency>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-compiler-plugin</artifactId>
<configuration>
<source>1.8</source>
<target>1.8</target>
</configuration>
</plugin>
</plugins>
</build>
</project>
3:创建City类和CityDao, 简单一点,City类只有id属性,CityDao只有一个方法getById
4:添加CityMapper.xml,仅有一个select语句
<?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.hhg.jerry.dao.CityDao">
<select id="getById"
resultType="com.hhg.jerry.model.City"
parameterType="java.lang.Long">
SELECT * FROM city where id = #{id}
</select>
</mapper>
5:mybatis的配置文件mybatis.xml, 仅有environments和mapers
<?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://localhost:3306/world"/>
<property name="username" value="root"/>
<property name="password" value="root"/>
</dataSource>
</environment>
</environments>
<mappers>
<mapper resource="CityMapper.xml"/>
</mappers>
</configuration>
5 : 自建一个类或用App.java,添加代码运行mybatis
package com.hhg.jerry;
import com.hhg.jerry.model.City;
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.InputStream;
/**
* Hello world!
*
*/
public class App {
public static void main( String[] args ) throws Exception{
InputStream inputStream = Resources.getResourceAsStream("mybatis.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
City city = sqlSession.selectOne("com.hhg.jerry.dao.CityDao.getById",1L);
System.out.println(city);
}
}
到此,mybatis源码就能debug了。
总结:这一篇主要目的是能debug mybatis,为了简化,mybatis的核心配置文件只加了environments和一个mappers,CityDao也只有一个方法,City也就有一个属性。下一篇会完善mybatis的配置及mapper对应的方法。
若环境有问题,也可从github上clone我上传的工程--->>>https://github.com/DimLighter/mybatis-gg