mybatis源码分析（一）

最近打算读读mybatis的源码来提高自己写bug的水平,hahaha

找到网站下载源码：https://github.com/mybatis/mybatis-3

使用idea进行关联，并且配置好环境之后。

配合中文文档进行搭建：

1.导入jdbc包，我用的 lombok

  <!-- https://mvnrepository.com/artifact/org.projectlombok/lombok -->
    <dependency>
      <groupId>org.projectlombok</groupId>
      <artifactId>lombok</artifactId>
      <version>1.16.18</version>
      <scope>provided</scope>
    </dependency>
<!--没有mysql依赖-->
    <!-- 数据库连接池、驱动 -->
    <!-- https://mvnrepository.com/artifact/mysql/mysql-connector-java-->
    <dependency>
      <groupId>mysql</groupId>
      <artifactId>mysql-connector-java</artifactId>
      <version>5.1.8</version>
    </dependency>

2.创建数据库连接的xml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="root"/>
            </dataSource>
        </environment>
    </environments>
    <mappers>
        <mapper resource="mybatis\UserMapper.xml"/>
    </mappers>
</configuration>

3.创建java对象

package java7115;

import lombok.*;

@Data
@Builder//链式调用<--
@RequiredArgsConstructor
@AllArgsConstructor
@ToString
public class User {
private  Integer id;
private  String username;
private  String password;
private  String  remarks;
private  String true_name;
}

4.编写mybatis的sql

<?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="java7115">
    <select id="selectUser" resultType="java7115.User">
    select * from User where id = #{id}
  </select>
</mapper>

5.

为了能显示sql增加日志

log4j.properties

#
#    Copyright 2009-2016 the original author or authors.
#
#    Licensed under the Apache License, Version 2.0 (the "License");
#    you may not use this file except in compliance with the License.
#    You may obtain a copy of the License at
#
#       http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS,
#    WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
#    See the License for the specific language governing permissions and
#    limitations under the License.
#

### Global logging configuration
log4j.rootLogger=debug, stdout

### Uncomment for MyBatis logging
log4j.logger.org.apache.ibatis=ERROR

log4j.logger.org.apache.ibatis.session.AutoMappingUnknownColumnBehavior=WARN, lastEventSavedAppender

### Console output...
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=%5p [%t] - %m%n

log4j.appender.lastEventSavedAppender=org.apache.ibatis.session.AutoMappingUnknownColumnBehaviorTest$LastEventSavedAppender

main方法测试

package org.apache.ibatis;

import java7115.User;
import lombok.extern.slf4j.Slf4j;
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.IOException;
import java.io.InputStream;

public class Main {
    public static void main(String[] args) throws IOException {

       String resource = "mybatis-config.xml";
        //读取配置文件
        InputStream inputStream = Resources.getResourceAsStream(resource);
        //创建连接工厂
        SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
        //得到session实例
        SqlSession session = sqlSessionFactory.openSession();
        try {
            //根据命名空间找方法
            User blog = (User) session.selectOne("java7115.selectUser", 1);
            System.out.println(blog);
        } finally {
            session.close();
        }
    }
}

输出结果：

DEBUG [main] - ==> Preparing: select * from User where id = ?
DEBUG [main] - ==> Parameters: 1(Integer)
DEBUG [main] - <== Total: 1
User(id=1, username=admin, password=123, remarks=管理员, true_name=王大陆)

这个是我当前目录图片