Spring declarative transactions

Transactions: a group of operations that either all succeed or fail;

Four key properties of a transaction (ACID):

<! --1. Configure a connection pool-->
    <bean id="comboPooledDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="user" value="root"></property>
        <property name="password" value= "123456"></property>
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
        <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/tx"></property>
    </bean>
<! --2. Add, delete, change and check JdbcTemplate of the database-->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="comboPooledDataSource"></property>
    </bean>
<! --Configure transaction facets; Control the connection pool-->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="comboPooledDataSource"></property>
    </bean>
    
<! --Enable annotation-based transactions. Depends on the TX namespace transaction-manager: specifies which transaction manager is-->
    <tx:annotation-driven/>Copy the code

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

/ * *Public int getPrice(String isbn); public int getPrice(String isbn); [2] Public void updateStock(String isbn); [3] Public void updateBalance(int price,String user); *@authorlfy ** /
@Repository
public classBookDao { @Autowired JdbcTemplate jdbcTemplate;/ * *Public int getPrice(String isbn); public int getPrice(String isbn); * Operation: book* /
    public intgetPrice(String isbn){ String sql= "select price from book where isbn=?"; Integer price= jdbcTemplate.queryForObject(sql, Integer.class, isbn);
        returnprice; };/ * *Public void updateStock(String isbn); public void updateStock(String isbn); * Action: book_stock* /
    public voidupdateStock(String isbn){ String sql= "UPDATE book_stock SET stock=stock-1 WHERE isbn=?"; jdbcTemplate.update(sql, isbn); }/ * *Public void updateBalance(int price,String user); public void updateBalance(int price,String user); * Reduce the balance of the user; Account * String user: user name to reduce the balance * int price: how much to reduce (the amount reduced is the book price)* /
    public void updateBalance(intprice,String user){ String sql= "update account set balance = balance-? where username=?"; jdbcTemplate.update(sql, price,user); }public voidupdatePrice(String isbn){ String sql= "update book set price = 999 WHERE isbn=?"; jdbcTemplate.update(sql, isbn); }}Copy the code

import java.io.FileInputStream;
import java.io.FileNotFoundException;

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;

importcom.atguigu.dao.BookDao; @Servicepublic classBookService { @Autowired BookDao bookDao; @Transactional(noRollbackFor=ArithmeticException.class, timeout=3,propagation=Propagation.REQUIRES_NEW)
    public void checkout(String username,String isbn){
        //Find out book prices
        int price = bookDao.getPrice(isbn);
        //1. Deduct the balance of users
        bookDao.updateBalance(price, username);
        //Reduce the inventory of books
        bookDao.updateStock(isbn);
        
        //Thread.sleep(3000);
        //new FileInputStream("D://ahahahah//aa.txt");System.out.println(" Checkout complete...."); } @Transactional(propagation=Propagation.REQUIRED,timeout=3)
    public void updatePrice(String isbn){
        try{ Thread.sleep(3000); }catch(InterruptedException e) { e.printStackTrace(); } bookDao.updatePrice(isbn); }}Copy the code

Isolation: The isolation level of a transaction, isolating individual transactions;

The isolation = isolation. READ_UNCOMMITTED;

According to actual business logic;

The following problems may occur if transactions are not applicable:

<?The 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"
    xmlns:aop="http://www.springframework.org/schema/aop"
    xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-4.0.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-4.0.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-4.0.xsd">

    <context:component-scan base-package="com.atguigu"></context:component-scan>
    
    <! --1. Configure a connection pool-->
    <bean id="comboPooledDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
        <property name="user" value="root"></property>
        <property name="password" value= "123456"></property>
        <property name="driverClass" value="com.mysql.jdbc.Driver"></property>
        <property name="jdbcUrl" value="jdbc:mysql://localhost:3306/tx"></property>
    </bean>
    
    <! --2. Add, delete, change and check JdbcTemplate of the database-->
    <bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="comboPooledDataSource"></property>
    </bean>
    
    <! --3. Configure transaction facets. Control the connection pool-->
    <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource" ref="comboPooledDataSource"></property>
    </bean>
    
    <! --4. Enable annotation-based transactions. Depends on the TX namespace transaction-manager: specifies which transaction manager is-->
    <! -- <tx:annotation-driven/> -->
    
    <! --Xml-based transaction configuration; Aop and TX namespaces are required-->
    <! --TransactionManager transaction facets-->
    <aop:config>
        <! --Specifies which methods the transaction manager should access for transaction control-->
        <aop:pointcut expression="execution(* com.soyoungboy.service.*.*(..) )" id="txPoint"/>
        <! --Aop :advisor: Pointcut-ref: Cuts into a transaction using the specified pointcut expression-->
        <aop:advisor advice-ref="myTxAdvice" pointcut-ref="txPoint"/>
    </aop:config>
    
    <! --Use tx namespaces and configurations (transaction recommendations, transaction attributes, transaction enhancement); Id ="myTxAdvice" : < AOP :advisor advice-ref="myTxAdvice" transaction-manager="transactionManager": specify which transaction manager to configure-->
    <tx:advice id="myTxAdvice" transaction-manager="transactionManager">
        <tx:attributes>
            <! --Specify transaction methods: represents that all methods are transaction methods-->
            <tx:method name= "*"/>
            <tx:method name="checkout" rollback-for="java.lang.Exception"/>
            <tx:method name="updatePrice" propagation="REQUIRES_NEW"/>
            <! --Those that begin with GET are optimized by reading only-->
            <tx:method name="get*" read-only="true"/>
        </tx:attributes>
    </tx:advice>
    
    <! --Transaction control based on XML configuration is a bit more-->


</beans>Copy the code