spring事物中的传播及隔离

软件测试君

发布于 2019-08-13 10:30:50

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发布于 2019-08-13 10:30:50

关于@Transactional注解：

添加事务注解

1、使用 propagation 指定事务的传播行为, 即当前的事务方法被另外一个事务方法调用时。如何使用事务, 默认取值为 REQUIRED, 即使用调用方法的事务REQUIRES_NEW: 事务自己的事务, 调用的事务方法的事务被挂起。

2、使用 isolation 指定事务的隔离级别, 最常用的取值为 READ_COMMITTED。

3、默认情况下 Spring 的声明式事务对所有的运行时异常进行回滚. 也可以通过对应的属性进行设置. 通常情况下去默认值即可。4、使用 readOnly 指定事务是否为只读. 表示这个事务只读取数据但不更新数据，这样可以帮助数据库引擎优化事务. 若真的是一个只读取数据库值的方法, 应设置 readOnly=true

5、使用 timeout 指定强制回滚之前事务可以占用的时间。

个人疑问有一些，结尾来说，用教程例子来说吧。

我的代码如下：

BookShopDao接口

package com.demo.spring.bean;

public interface BookShopDao {

    //根据书的编号返回书的单价
    public int findBookPriceByIsbn(String isbn);
    //根据书的编号返回输的库存
    public void updateBookStock(String isbn);
    //更新用户账户余额
    public void updateUserAccount(String username, int price);
}

实现类

package com.demo.spring.bean;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jdbc.core.JdbcTemplate;
import org.springframework.stereotype.Repository;

@Repository("bookShopDao")
public class BookShopDaoImpl implements BookShopDao {
    @Autowired
    private JdbcTemplate jdbcTemplate;

    @Override
    public int findBookPriceByIsbn(String isbn) {
        // TODO Auto-generated method stub
        String sql = "SELECT price FROM book WHERE isbn=?";
        Integer price = jdbcTemplate.queryForObject(sql, Integer.class, isbn);
        return price;
    }

    @Override
    public void updateBookStock(String isbn) {
        // TODO Auto-generated method stub
        String sql = "SELECT stock FROM book_stock WHERE isbn= ? ";
        Integer stock = jdbcTemplate.queryForObject(sql, Integer.class, isbn);
        if (stock == 0) {
            throw new BookStockException("库存不足！！");
        }
        String sql1 = "UPDATE book_stock SET stock=stock-1 WHERE isbn=?";
        jdbcTemplate.update(sql1, isbn);
    }

    @Override
    public void updateUserAccount(String username, int price) {
        // TODO Auto-generated method stub
        String sql1 = "SELECT balance FROM account WHERE username= ? ";
        Integer account = jdbcTemplate.queryForObject(sql1, Integer.class,
                username);
        if (account < price) {
            throw new AccountException("余额不足！！");
        }
        String sql = "UPDATE account SET balance=balance-? WHERE username=?";
        jdbcTemplate.update(sql, price, username);
    }

}

BookShopService接口

package com.demo.spring.bean;

public interface BookShopService {
//购书
public void purchase(String username, String isbn);
}

实现类

package com.demo.spring.bean;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

@Service("bookShopService")
public class BookShopServiceImpl implements BookShopService {


    @Autowired
    private BookShopDao bookShopDao;
// @Transactional(propagation=Propagation.REQUIRES_NEW,isolation=Isolation.READ_COMMITTED,readOnly=true,timeout=5,noRollbackFor=AccountException.class)

    @Transactional
    @Override
    public void purchase(String username, String isbn) {

        try {
            Thread.sleep(5000);
        } catch (InterruptedException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        // TODO Auto-generated method stub
        int price = bookShopDao.findBookPriceByIsbn(isbn);
        bookShopDao.updateBookStock(isbn);
        bookShopDao.updateUserAccount(username, price);
    }

}

Cashier批量购书接口

package com.demo.spring.bean;

import java.util.List;

public interface Cashier {
    //批量购书
    public void checkout(String username, List<String> isbns);

}

实现类

package com.demo.spring.bean;

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;


@Service("cashier")
public class CashierImpl implements Cashier {

    @Autowired
    private BookShopService bookShopService;
//    @Transactional
    @Override
    public void checkout(String username, List<String> isbns) {
        // TODO Auto-generated method stub
        for (String isbn : isbns) {
            bookShopService.purchase(username, isbn);
        }

    }

}

账户余额不足异常（自定义异常）

package com.demo.spring.bean;

public class AccountException extends RuntimeException {

    /**
     *
     */
    private static final long serialVersionUID = 1L;

    public AccountException() {
        super();
        // TODO Auto-generated constructor stub
    }

    public AccountException(String message, Throwable cause,
            boolean enableSuppression, boolean writableStackTrace) {
        super(message, cause, enableSuppression, writableStackTrace);
        // TODO Auto-generated constructor stub
    }

    public AccountException(String message, Throwable cause) {
        super(message, cause);
        // TODO Auto-generated constructor stub
    }

    public AccountException(String message) {
        super(message);
        // TODO Auto-generated constructor stub
    }

    public AccountException(Throwable cause) {
        super(cause);
        // TODO Auto-generated constructor stub
    }


}

库存不足异常（自定义异常）

package com.demo.spring.bean;

public class BookStockException extends RuntimeException {

    private static final long serialVersionUID = 1L;

    public BookStockException() {
        super();
        // TODO Auto-generated constructor stub
    }

    public BookStockException(String message, Throwable cause,
            boolean enableSuppression, boolean writableStackTrace) {
        super(message, cause, enableSuppression, writableStackTrace);
        // TODO Auto-generated constructor stub
    }

    public BookStockException(String message, Throwable cause) {
        super(message, cause);
        // TODO Auto-generated constructor stub
    }

    public BookStockException(String message) {
        super(message);
        // TODO Auto-generated constructor stub
    }

    public BookStockException(Throwable cause) {
        super(cause);
        // TODO Auto-generated constructor stub
    }


}

测试类

package com.demo.spring.bean;

import java.util.Arrays;

import org.junit.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class MainTest {


    private ApplicationContext ctx;
    @Autowired
    private Cashier cashier;
    {
        ctx=new ClassPathXmlApplicationContext("bean.xml");
        cashier=(Cashier) ctx.getBean("cashier");
    }

     @Test
     public void test(){
//         System.out.println(bookShopDao.findBookPriceByIsbn("1001"));
         cashier.checkout("rongrong", Arrays.asList("1001","1002"));
     }



}

bean文件

<?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:aop="http://www.springframework.org/schema/aop"
    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-3.2.xsd
        http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.1.xsd
        http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.1.xsd
        http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.1.xsd">
    <!-- 装载自导导入的包 -->
    <context:component-scanbase-package="com.demo.spring.bean"></context:component-scan>
    <!-- 引入外部数据源 -->
    <context:property-placeholder location="classpath:db.properties"/>
    <!-- 配置mysql数据源 -->
    <bean id="datasource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
        <property name="driverClassName" value="${db.driverClassName}"></property>
        <property name="url" value="${db.url}"></property>
        <property name="username" value="${db.username}"></property>
        <property name="password" value="${db.password}"></property>
    </bean>
    <!-- 配置jdbc模板 -->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="datasource"></property>
    </bean>
    <!-- 配置事务管理器 -->
    <bean id="transactionManagertest" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="datasource"></property>
    </bean>    
    <!-- 启用事务注解 -->
    <tx:annotation-driven transaction-manager="transactionManagertest"/>

</beans>

数据源

db.driverClassName=com.mysql.jdbc.Driver
db.url=jdbc:mysql://localhost:3306/spring
db.username=root
db.password=root

疑问如下：

1、前提条件：用户按照1001，1002这种顺序去购书，调用checkout接口批量购书 @Transactional注解确实满足原子性操作，要么都做，要么不做但是，我试验了下，如果在public void checkout(String username, Listisbns) 上方不加Transactional注解与在public void purchase(String username, String isbn)上方加@Transactional(propagation=Propagation.REQUIRES_NEW效果一样

2、当账户余额为120，可以满足账户减去1001的单价，1001的库存减1 但是，将账户余额改为80，从单价上看可以买1002那本书，按照上面的顺序去买书，按照上面加上注解@Transactional(propagation=Propagation.REQUIRES_NEW效果一样，根本不好使，我个人觉得因为在更新账户余额，那有个判断先查询1001的书的单价确实大于当前账户余额80，先判断了，所以抛异常后面代码就不走了

3、另外当前账户余额可以买1002这本书，想在不改变购书的顺序情况下，用@Transactional注解实现，可以买1002这本书？，减去当前账户余额80，更新1002书的库存，哪位大神看到，帮我看下，怎么用这个注解实现？

以上为我的个人疑惑的点，有兴趣的同学可以研究下，然后在公号留言给我即可，小编不胜感谢！

附上：sql

/*
Navicat MySQL Data Transfer

Source Server         : myTestdata
Source Server Version : 50627
Source Host           : localhost:3306
Source Database       : spring

Target Server Type    : MYSQL
Target Server Version : 50627
File Encoding         : 65001

Date: 2017-01-18 11:28:50
*/

SET FOREIGN_KEY_CHECKS=0;

-- ----------------------------
-- Table structure for account
-- ----------------------------
DROP TABLE IF EXISTS `account`;
CREATE TABLE `account` (
  `username` varchar(50) NOT NULL,
  `balance` int(11) DEFAULT NULL,
  PRIMARY KEY (`username`)
) ENGINE=InnoDB DEFAULT CHARSET=gbk;

-- ----------------------------
-- Records of account
-- ----------------------------
INSERT INTO `account` VALUES ('rongrong', '300');
INSERT INTO `account` VALUES ('zhangsan', '200');

-- ----------------------------
-- Table structure for book
-- ----------------------------
DROP TABLE IF EXISTS `book`;
CREATE TABLE `book` (
  `isbn` varchar(50) NOT NULL,
  `book_name` varchar(100) DEFAULT NULL,
  `price` int(11) DEFAULT NULL,
  PRIMARY KEY (`isbn`)
) ENGINE=InnoDB DEFAULT CHARSET=gbk;

-- ----------------------------
-- Records of book
-- ----------------------------
INSERT INTO `book` VALUES ('1001', 'java', '100');
INSERT INTO `book` VALUES ('1002', 'python', '60');

-- ----------------------------
-- Table structure for book_stock
-- ----------------------------
DROP TABLE IF EXISTS `book_stock`;
CREATE TABLE `book_stock` (
  `isbn` varchar(50) NOT NULL,
  `bookname` varchar(100) DEFAULT NULL,
  `stock` int(11) DEFAULT NULL,
  PRIMARY KEY (`isbn`)
) ENGINE=InnoDB DEFAULT CHARSET=gbk;

-- ----------------------------
-- Records of book_stock
-- ----------------------------
INSERT INTO `book_stock` VALUES ('1001', 'java', '10');
INSERT INTO `book_stock` VALUES ('1002', 'python', '10');

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原始发表：2019-08-10，如有侵权请联系 cloudcommunity@tencent.com 删除

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