Spring SpringMVC Mybatis（简称ssm）是一个很流行的java web框架，而Mybatis作为ORM 持久层框架，因其灵活简单，深受青睐。而且现在的招聘职位中都要求应试者熟悉Mybatis框架。我认为有必要分析一下Mybatis的源码。在进行源码分析前，先准备一个简单的工程。如果你还不会使用maven请参考：Maven 创建项目之简单示例，创建一个简单的工程。
开发工具：eclipse
jdk版本：1.8
1，创建好的工程目录如下图所示：
2，现在来添加工程的依赖包，配置如下：
<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.zcz</groupId>
<artifactId>learnmybatis</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>learnmybatis</name>
<description>learnmybatis</description>
<dependencies>
<!-- 添加junit -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.11</version>
<scope>test</scope>
</dependency>
<!-- 添加log4j -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.16</version>
</dependency>
<!-- 添加mybatis -->
<dependency>
<groupId>org.mybatis</groupId>
<artifactId>mybatis</artifactId>
<version>3.2.6</version>
</dependency>
<!-- 添加mysql驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.44</version>
</dependency>
</dependencies>
</project>
3，在src/main/resources中添加log4j配置log4j.properties，配置内容如下：
# priority :debug<info<warn<error
#you cannot specify every priority with different file for log4j
log4j.rootLogger=debug,stdout,info,debug,warn,error #console
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern= [%d{yyyy-MM-dd HH:mm:ss a}]:%p %l%m%n
#info log
log4j.logger.info=info
log4j.appender.info=org.apache.log4j.DailyRollingFileAppender
log4j.appender.info.DatePattern='_'yyyy-MM-dd'.log'
log4j.appender.info.File=./src/com/hp/log/info.log
log4j.appender.info.Append=true
log4j.appender.info.Threshold=INFO
log4j.appender.info.layout=org.apache.log4j.PatternLayout
log4j.appender.info.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss a} [Thread: %t][ Class:%c >> Method: %l ]%n%p:%m%n
#debug log
log4j.logger.debug=debug
log4j.appender.debug=org.apache.log4j.DailyRollingFileAppender
log4j.appender.debug.DatePattern='_'yyyy-MM-dd'.log'
log4j.appender.debug.File=./src/com/hp/log/debug.log
log4j.appender.debug.Append=true
log4j.appender.debug.Threshold=DEBUG
log4j.appender.debug.layout=org.apache.log4j.PatternLayout
log4j.appender.debug.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss a} [Thread: %t][ Class:%c >> Method: %l ]%n%p:%m%n
#warn log
log4j.logger.warn=warn
log4j.appender.warn=org.apache.log4j.DailyRollingFileAppender
log4j.appender.warn.DatePattern='_'yyyy-MM-dd'.log'
log4j.appender.warn.File=./src/com/hp/log/warn.log
log4j.appender.warn.Append=true
log4j.appender.warn.Threshold=WARN
log4j.appender.warn.layout=org.apache.log4j.PatternLayout
log4j.appender.warn.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss a} [Thread: %t][ Class:%c >> Method: %l ]%n%p:%m%n
#error
log4j.logger.error=error
log4j.appender.error = org.apache.log4j.DailyRollingFileAppender
log4j.appender.error.DatePattern='_'yyyy-MM-dd'.log'
log4j.appender.error.File = ./src/com/hp/log/error.log
log4j.appender.error.Append = true
log4j.appender.error.Threshold = ERROR
log4j.appender.error.layout = org.apache.log4j.PatternLayout
log4j.appender.error.layout.ConversionPattern = %d{yyyy-MM-dd HH:mm:ss a} [Thread: %t][ Class:%c >> Method: %l ]%n%p:%m%n
4.接下来在src/main/resources中添加mybatis的配置文件configuration.xml。配置如下：
<?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> <!-- 指定properties配置文件， 我这里面配置的是数据库相关 -->
<properties resource="dbConfig.properties"></properties> <!-- 指定Mybatis使用log4j -->
<settings>
<setting name="logImpl" value="LOG4J"/>
</settings> <environments default="development">
<environment id="development">
<transactionManager type="JDBC"/>
<dataSource type="POOLED">
<!--
如果上面没有指定数据库配置的properties文件，那么此处可以这样直接配置
<property name="driver" value="com.mysql.jdbc.Driver"/>
<property name="url" value="jdbc:mysql://localhost:3306/learnMybatis"/>
<property name="username" value="root"/>
<property name="password" value="123"/> --> <!-- 上面指定了数据库配置文件， 配置文件里面也是对应的这四个属性 -->
<property name="driver" value="${driver}"/>
<property name="url" value="${url}"/>
<property name="username" value="${username}"/>
<property name="password" value="${password}"/> </dataSource>
</environment>
</environments> <!-- 映射文件，mybatis精髓， 后面才会细讲 -->
<mappers>
<mapper resource="mapper/userDao-mapping.xml"/>
</mappers> </configuration>
5.然后在src/main/resources中添加数据库配置文件：dbConfig.properties，配置如下：
driver=com.mysql.jdbc.Driver
url=jdbc:mysql://localhost:3306/learnmybatis
username=root
password=123
6.在src/main/resources中添加mapper包，这个包中存放是的mybatis的mapper文件。
7.新建learnmybatis数据库，并创建表：user。表结构如图所示：
插入一条数据：
8.准备工作完成，接下来就是代码实现了，我们先看一下这个时候的工程目录结构,如下图：
9.在src/main/java中新增包：com.zcz.learnmybatis.entity，并在次包下新增类User:
package com.zcz.learnmybatis.entity;
public class User {
private int id;
private String name;
private String password;
private int age;
private int deleteFlag;
public int getId() {
return id;
}
public void setId(int id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getPassword() {
return password;
}
public void setPassword(String password) {
this.password = password;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}
public int getDeleteFlag() {
return deleteFlag;
}
public void setDeleteFlag(int deleteFlag) {
this.deleteFlag = deleteFlag;
}
}
10.在src/main/java中新增包：com.zcz.learnmybatis.dao，并在次包下新增类UserDao:
package com.zcz.learnmybatis.dao;
import java.util.List;
import com.zcz.learnmybatis.entity.User;
public interface UserDao {
public void insert(User user);
public User findUserById(int userId);
public List<User> findAllUsers();
}
11,在mapper中新增userDao-mapping.xml文件：
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper
PUBLIC "-//ibatis.apache.org//DTD Mapper 3.0//EN"
"http://ibatis.apache.org/dtd/ibatis-3-mapper.dtd">
<mapper namespace="com.zcz.learnmybatis.dao.UserDao"> <select id="findUserById" resultType="com.zcz.learnmybatis.entity.User" >
select * from user where id = #{id}
</select> </mapper>
12，在src/test/java中新增包：com.test.learnmybatis，并在次包下新增类：UserDaoTest:
类中使用了@Test注解，不会使用的情查看 常用注解记录
package com.test.learnmybatis; 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.Test; import com.zcz.learnmybatis.dao.UserDao;
import com.zcz.learnmybatis.entity.User; import junit.framework.Assert; public class UserDaoTest {
@Test
public void finUserById() {
SqlSession sqlSession = getSessionFactory().openSession();
UserDao userMapper = sqlSession.getMapper(UserDao.class);
User user = userMapper.findUserById(1);
Assert.assertNotNull("not find", user); } private static SqlSessionFactory getSessionFactory() {
SqlSessionFactory sessionFactory = null;
String resource = "configuration.xml";
try {
sessionFactory = new SqlSessionFactoryBuilder().build(Resources.getResourceAsReader(resource));
}catch (Exception e) {
// TODO: handle exception
e.printStackTrace();
}
return sessionFactory;
}
}
13.到这里所有的准备工作已经完成了，现在看一下目录结构：
14.在UserDaoTest中右键->Run As->JUnit Test。可以看到，运行成功了：
15，到这里这个简单的mybatis就创建成功了，接下来就开始源码的跟踪与分析吧，接下来就是激动人心的时刻了 -------> Mybatis源码解析，一步一步从浅入深（二）：按步骤解析源码。
工程已经上传github:https://github.com/ZCC1/learnmybatis.
需要的伙伴可以去clone.
最后不得不提的是：在使用5.1.12版本的mysql驱动包的时候遇到了一个问题：Cause: java.sql.SQLException: Error setting driver on UnpooledDataSource. Cause: java.lang.ClassNotFoundException: Cannot find class: com.mysql.jdbc.Driver。
我另外写了一篇文章，给出了异常的详细内容和解决办法：Cannot find class: com.mysql.jdbc.Driver错误及解决办法。
原创不易，转载请声明出处：https://www.cnblogs.com/zhangchengzi/p/9669707.html