MyBatis配置数据源

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一、设置Mybatis配置文件

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><settings><!-- 这个配置使全局的映射器启用或禁用缓存。默认true --><setting name="cacheEnabled" value="true"/><!-- 全局启用或禁用延迟加载。默认true --><setting name="lazyLoadingEnabled" value="true"/><!-- 允许或不允许多种结果集从一个单独的语句中返回。默认true --><setting name="multipleResultSetsEnabled" value="true"/></settings><!-- 类型别名是为Java类型命名一个短的名字。它只和XML配置有关，只用来减少类完全限定名的多余部分。 --><typeAliases><typeAlias alias="Student" type="cn.test.entity.Student"/><typeAlias alias="Group" type="cn.test.entity.Group"/></typeAliases><environments default="mySql"><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}"/><!-- 在任意时间存在的活动（也就是正在使用）连接的数量。默认值：10 --><property name="poolMaximumActiveConnections" value="10"/>                  <!-- 任意时间存在的空闲连接数 -->                <property name="poolMaximumIdleConnections" value="5"/>                  <!-- 在被强制返回之前，池中连接被检查的时间。默认值：20000毫秒（也就是20秒） -->                 <property name="poolMaximumCheckoutTime" value="20000"/>                 <property name="poolTimeToWait" value="20000"/>  </dataSource></environment><environment id="mySql"><transactionManager type="JDBC"/><dataSource type="POOLED"><property name="driver" value="com.mysql.jdbc.Driver"/><property name="url" value="jdbc:mysql://localhost:3306/test"/><property name="username" value="root"/><property name="password" value="123456"/></dataSource></environment><environment id="oracle"><transactionManager type="JDBC"/><dataSource type="POOLED"><property name="driver" value="oracle.jdbc.driver.OracleDriver"/><property name="url" value="jdbc:oracle:thin:@localhost:1521:ORCL"/><property name="username" value="mm"/><property name="password" value="123456"/></dataSource></environment></environments><mappers><mapper resource="cn/test/data/StudentMapper.xml"/><mapper resource="cn/test/data/GroupMapper.xml"/></mappers></configuration>

二、写工具类MybatisUtils

package cn.test.utils;import java.io.IOException;import java.io.Reader;import org.apache.ibatis.io.Resources;import org.apache.ibatis.session.SqlSession;import org.apache.ibatis.session.SqlSessionFactory;import org.apache.ibatis.session.SqlSessionFactoryBuilder;public class MyBatisUtils {private static final String RESOURCE = "mybatis-config.xml";private static SqlSessionFactory sqlSessionFactory;private static ThreadLocal<SqlSession> threadLocal = new ThreadLocal<SqlSession>();static{try {Reader reader = Resources.getResourceAsReader(RESOURCE);SqlSessionFactoryBuilder builder = new SqlSessionFactoryBuilder();sqlSessionFactory = builder.build(reader);} catch (IOException e) {e.printStackTrace();throw new ExceptionInInitializerError("初始化MyBatis错误！请检查配置文件或者数据库");}}//得到一个SqlSessionpublic static SqlSession getSession(){SqlSession session = threadLocal.get();if(session==null){session = sqlSessionFactory.openSession();threadLocal.set(session);}return session;}//关闭当前线程的SqlSessionpublic static void closeSession(){SqlSession session = threadLocal.get();threadLocal.set(null);if(session!=null){session.close();}}}

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