Spring 事務

時間 2019-11-13

標籤 spring 事務欄目 Spring 简体版

原文原文鏈接

4.2 一個聲明式事務的實例

首先是數據庫表

book(isbn, book_name, price) 
account(username, balance) 
book_stock(isbn, stock)

而後是XML配置

<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:aop="http://www.springframework.org/schema/aop"
xmlns:tx="http://www.springframework.org/schema/tx"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http://www.springframework.org/schema/context
http://www.springframework.org/schema/context/spring-context-3.0.xsd
http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">

    <import resource="applicationContext-db.xml" />

    ////自動掃描包
    <context:component-scan
        base-package="com.springinaction.transaction">
    </context:component-scan>

    <tx:annotation-driven transaction-manager="txManager"/>

    ///JDBC事務管理類

    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="dataSource" />
    </bean>

</beans>

使用的類

BookShopDaohtml

package com.springinaction.transaction;

public interface BookShopDao {
    // 根據書號獲取書的單價
    public int findBookPriceByIsbn(String isbn);
    // 更新書的庫存，使書號對應的庫存-1
    public void updateBookStock(String isbn);
    // 更新用戶的帳戶餘額：account的balance-price
    public void updateUserAccount(String username, int price);
}

BookShopDaoImpljava

package com.springinaction.transaction;

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) {
        String sql = "SELECT price FROM book WHERE isbn = ?";

        return JdbcTemplate.queryForObject(sql, Integer.class, isbn);
    }

    @Override
    public void updateBookStock(String isbn) {
        //檢查書的庫存是否足夠，若不夠，則拋出異常
        String sql2 = "SELECT stock FROM book_stock WHERE isbn = ?";
        int stock = JdbcTemplate.queryForObject(sql2, Integer.class, isbn);
        if (stock == 0) {
            throw new BookStockException("庫存不足！");
        }
        String sql = "UPDATE book_stock SET stock = stock - 1 WHERE isbn = ?";
        JdbcTemplate.update(sql, isbn);
    }

    @Override
    public void updateUserAccount(String username, int price) {
        //檢查餘額是否不足，若不足，則拋出異常
        String sql2 = "SELECT balance FROM account WHERE username = ?";
        int balance = JdbcTemplate.queryForObject(sql2, Integer.class, username);
        if (balance < price) {
            throw new UserAccountException("餘額不足！");
        }       
        String sql = "UPDATE account SET balance = balance - ? WHERE username = ?";
        JdbcTemplate.update(sql, price, username);
    }

}

BookShopServicespring

package com.springinaction.transaction;
public interface BookShopService {
     public void purchase(String username, String isbn);
}

BookShopServiceImplsql

package com.springinaction.transaction;

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

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

    @Autowired
    private BookShopDao bookShopDao;

    /**
     * 1.添加事務註解
     * 使用propagation 指定事務的傳播行爲，即當前的事務方法被另一個事務方法調用時如何使用事務。
     * 默認取值爲REQUIRED，即便用調用方法的事務
     * REQUIRES_NEW：使用本身的事務，調用的事務方法的事務被掛起。
     *
     * 2.使用isolation 指定事務的隔離級別，最經常使用的取值爲READ_COMMITTED
     * 3.默認狀況下 Spring 的聲明式事務對全部的運行時異常進行回滾，也能夠經過對應的屬性進行設置。一般狀況下，默認值便可。
     * 4.使用readOnly 指定事務是否爲只讀。 表示這個事務只讀取數據但不更新數據，這樣能夠幫助數據庫引擎優化事務。若真的是一個只讀取數據庫值得方法，應設置readOnly=true
     * 5.使用timeOut 指定強制回滾以前事務能夠佔用的時間。
     */
    @Transactional(propagation=Propagation.REQUIRES_NEW,
            isolation=Isolation.READ_COMMITTED,
            noRollbackFor={UserAccountException.class},
            readOnly=true, timeout=3)
    @Override
    public void purchase(String username, String isbn) {
        //1.獲取書的單價
        int price = bookShopDao.findBookPriceByIsbn(isbn);
        //2.更新書的庫存
        bookShopDao.updateBookStock(isbn);
        //3.更新用戶餘額
        bookShopDao.updateUserAccount(username, price);
    }
}

Cashier數據庫

package com.springinaction.transaction;
import java.util.List;
public interface Cashier {
    public void checkout(String username, List<String>isbns);
}

CashierImpl：CashierImpl.checkout和bookShopService.purchase聯合測試了事務的傳播行爲app

package com.springinaction.transaction;

import java.util.List;

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

@Service("cashier")
public class CashierImpl implements Cashier {
    @Autowired
    private BookShopService bookShopService;

    @Transactional
    @Override
    public void checkout(String username, List<String> isbns) {
        for(String isbn : isbns) {
            bookShopService.purchase(username, isbn);
        }
    }
}

BookStockExceptionide

package com.springinaction.transaction;
public class BookStockException extends RuntimeException {

    private static final long serialVersionUID = 1L;

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

    public BookStockException(String arg0, Throwable arg1, boolean arg2,
            boolean arg3) {
        super(arg0, arg1, arg2, arg3);
        // TODO Auto-generated constructor stub
    }

    public BookStockException(String arg0, Throwable arg1) {
        super(arg0, arg1);
        // TODO Auto-generated constructor stub
    }

    public BookStockException(String arg0) {
        super(arg0);
        // TODO Auto-generated constructor stub
    }

    public BookStockException(Throwable arg0) {
        super(arg0);
        // TODO Auto-generated constructor stub
    }
}

UserAccountException測試

package com.springinaction.transaction;
public class UserAccountException extends RuntimeException {

    private static final long serialVersionUID = 1L;

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

    public UserAccountException(String arg0, Throwable arg1, boolean arg2,
            boolean arg3) {
        super(arg0, arg1, arg2, arg3);
        // TODO Auto-generated constructor stub
    }

    public UserAccountException(String arg0, Throwable arg1) {
        super(arg0, arg1);
        // TODO Auto-generated constructor stub
    }

    public UserAccountException(String arg0) {
        super(arg0);
        // TODO Auto-generated constructor stub
    }

    public UserAccountException(Throwable arg0) {
        super(arg0);
        // TODO Auto-generated constructor stub
    }
}

測試類優化

package com.springinaction.transaction;

import java.util.Arrays;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class SpringTransitionTest {

    private ApplicationContext ctx = null;
    private BookShopDao bookShopDao = null;
    private BookShopService bookShopService = null;
    private Cashier cashier = null;
    {
        ctx = new ClassPathXmlApplicationContext("config/transaction.xml");
        bookShopDao = ctx.getBean(BookShopDao.class);
        bookShopService = ctx.getBean(BookShopService.class);
        cashier = ctx.getBean(Cashier.class);
    }

    @Test
    public void testBookShopDaoFindPriceByIsbn() {
        System.out.println(bookShopDao.findBookPriceByIsbn("1001"));
    }

    @Test
    public void testBookShopDaoUpdateBookStock(){
        bookShopDao.updateBookStock("1001");
    }

    @Test
    public void testBookShopDaoUpdateUserAccount(){
        bookShopDao.updateUserAccount("AA", 100);
    }
    @Test
    public void testBookShopService(){
        bookShopService.purchase("AA", "1001");
    }

    @Test
    public void testTransactionPropagation(){
        cashier.checkout("AA", Arrays.asList("1001", "1002"));
    }
}