Spring事务的隔离级别介绍说明以及怎么去修改Spring事务的隔离级别

@Transactional(propagation = Propagation.REQUIRES_NEW)
public void buyGoodsByTxISOLATION(int user_id, int goods_id, int num) {
//查询到商品价格
Float goods_price = goodsDao.queryPriceById(goods_id);
System.out.println("第一次读取的价格 = " + goods_price);
//测试一下隔离级别，在同一个事务中，查询一下价格
goods_price = goodsDao.queryPriceById(goods_id);
System.out.println("第二次读取的价格 = " + goods_price);
}

@Test
public void buyGoodsByTxISOLATIONTest() {
ApplicationContext ioc = new ClassPathXmlApplicationContext("tx_ioc.xml");
GoodsService bean = ioc.getBean(GoodsService.class);
bean.buyGoodsByTxISOLATION(1, 1, 1);
System.out.println("------ok--------");
}

@Test
public void buyGoodsByTxISOLATIONTest() {
    ApplicationContext ioc = new ClassPathXmlApplicationContext("tx_ioc.xml");
        GoodsService bean = ioc.getBean(GoodsService.class);
        bean.buyGoodsByTxISOLATION(1, 1, 1);
        System.out.println("------ok--------");
}

@Transactional(timeout = 2)
public void buyGoodsByTxTimeout(int user_id, int goods_id, int num) {
//查询到商品价格
Float goods_price = goodsDao.queryPriceById02(goods_id);
//购买商品，减去余额
goodsDao.updateBalance02(user_id, goods_price * num);
System.out.println("====超时 start====");
try {
Thread.sleep(4000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("====超时 end====");
//更新库存
goodsDao.updateAmount02(goods_id, num);
}

@Test
public void buyGoodsByTxTimeoutTest() {
    ApplicationContext ioc = new ClassPathXmlApplicationContext("tx_ioc.xml");
        GoodsService bean = ioc.getBean(GoodsService.class);
        bean.buyGoodsByTxTimeout(1, 1, 1);
        System.out.println("------ok--------");
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context https://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd">
    <!--配置要扫描的包-->
    <context:component-scan base-package="com.spring.tx.dao"/>
    <context:component-scan base-package="com.spring.tx.service"/>
    <!--引入外部的jdbc.properties文件-->
    <context:property-placeholder location="classpath:jdbc.properties"/>
    <!--配置数据源对象-DataSoruce-->
    <bean class="com.mchange.v2.c3p0.ComboPooledDataSource" id="dataSource">
        <!--给数据源对象配置属性值-->
        <property name="user" value="${jdbc.user}"/>
        <property name="password" value="${jdbc.pwd}"/>
        <property name="driverClass" value="${jdbc.driver}"/>
        <property name="jdbcUrl" value="${jdbc.url}"/>
    </bean>
    <!--配置JdbcTemplate对象-->
    <bean class="org.springframework.jdbc.core.JdbcTemplate" id="jdbcTemplate">
        <!--给JdbcTemplate对象配置dataSource-->
        <property name="dataSource" ref="dataSource"/>
    </bean>
    <!--配置事务管理器-对象
    1. DataSourceTransactionManager 这个对象是进行事务管理-debug源码
    2. 一定要配置数据源属性，这样指定该事务管理器 是对哪个数据源进行事务控制
    -->
    <bean class="org.springframework.jdbc.datasource.DataSourceTransactionManager" id="transactionManager">
        <property name="dataSource" ref="dataSource"/>
    </bean>
    <!--配置启动基于注解的声明式事务管理功能-->
    <tx:annotation-driven transaction-manager="transactionManager"/>
</beans>