Mybatis框架--优化过程

0. 原代码预览

简单实现在数据库中插入数据

<pre class="prettyprint hljs cs" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; word-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">public void testInsert() throws IOException {
//获取核心配置文件的输入流
InputStream is = Resources.getResourceAsStream("mybatis-config.xml");
//获取SqlSessionFactoryBuilder对象
SqlSessionFactoryBuilder sqlSessionFactoryBuilder = new SqlSessionFactoryBuilder();
//获取SqlSessionFactory对象
SqlSessionFactory sqlSessionFactory = sqlSessionFactoryBuilder.build(is);
//获取sql的回话对象sqlSession，是Mybatis提供的操作数据库的对象
SqlSession sqlSession = sqlSessionFactory.openSession();

    //获取UserMapper的代理实现类对象
    UserMapper mapper = sqlSession.getMapper(UserMapper.class);
    //调用mapper接口中的方法，实现添加用户信息的功能
    int result = mapper.insertUser();
    System.out.println("结果："+result);

    //提交事务
    sqlSession.commit();

    //关闭sqlSession对象
    sqlSession.close();
}</pre>

• SqlSession：代表Java程序和数据库之间的会话。（HttpSession是Java程序和浏览器之间的会话）
• SqlSessionFactory：是“生产”SqlSession的“工厂”。

1. 简化代码

根据两个一致性，可以将 获取UserMapper的代理实现类对象 和 调用mapper接口中的方法 两部分代码写为：

<pre class="prettyprint hljs verilog" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; word-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">//例如我的代码：
int result = sqlSession.insert("com.atguigu.mybatis.insertUser");//参数是：全类名+方法名。也就是映射文件中sql的id位置</pre>

2. 自动提交sql事务

每次都需要手动提交SQL事务 sqlSession.commit() 。可以在 获取sql的回话对象sqlSession 的代码： sqlSessionFactory.openSession() 加一个参数：

<pre class="hljs nginx" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 0.75em; font-size: 14px; line-height: 1.5em; word-break: break-all; word-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto; font-style: normal; font-variant-ligatures: normal; font-variant-caps: normal; font-weight: 400; letter-spacing: normal; orphans: 2; text-align: start; text-indent: 0px; text-transform: none; widows: 2; word-spacing: 0px; -webkit-text-stroke-width: 0px; text-decoration-style: initial; text-decoration-color: initial;">SqlSession sqlSession = sqlSessionFactory.openSession(true);</pre>

3. 加入log4j日志功能

• 在pom.xml中加入依赖

  <pre class="prettyprint hljs xml" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; word-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;">
  <dependency>
  <groupId>log4j</groupId>
  <artifactId>log4j</artifactId>
  <version>1.2.12</version>
  </dependency></pre>

• 加入log4j的配置文件

  log4j的配置文件名必须为log4j.xml，存放的位置是src/main/resources目录下

  <pre class="prettyprint hljs dust" style="padding: 0.5em; font-family: Menlo, Monaco, Consolas, "Courier New", monospace; color: rgb(68, 68, 68); border-radius: 4px; display: block; margin: 0px 0px 1.5em; font-size: 14px; line-height: 1.5em; word-break: break-all; word-wrap: break-word; white-space: pre; background-color: rgb(246, 246, 246); border: none; overflow-x: auto;"><?xml version="1.0" encoding="UTF-8" ?>
  <!DOCTYPE log4j:configuration SYSTEM "log4j.dtd">
  <log4j:configuration xmlns:log4j="http://jakarta.apache.org/log4j/">
  <appender name="STDOUT" class="org.apache.log4j.ConsoleAppender">
  <param name="Encoding" value="UTF-8" />
  <layout class="org.apache.log4j.PatternLayout">
  <param name="ConversionPattern" value="%-5p %d{MM-dd HH:mm:ss,SSS} %m (%F:%L) \n" />
  </layout>
  </appender>
  <logger name="java.sql">
  <level value="debug" />
  </logger>
  <logger name="org.apache.ibatis">
  <level value="info" />
  </logger>
  <root>
  <level value="debug" />
  <appender-ref ref="STDOUT" />
  </root>
  </log4j:configuration></pre>

  重新运行代码，查看日志功能：

  image.png