用注解的方式加事务

用注解的方式加事务

在applicationContext.xml里写：
<? 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:p = " http://www.springframework.org/schema/p "
         xmlns:aop = " http://www.springframework.org/schema/aop "
         xmlns:tx = " http://www.springframework.org/schema/tx "
       xmlns:context = " http://www.springframework.org/schema/context "
       xsi:schemaLocation = "
http: // www.springframework.org/schema/beans  http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
http: // www.springframework.org/schema/aop  http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
http: // www.springframework.org/schema/tx  http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
http: // www.springframework.org/schema/context  http://www.springframework.org/schema/context/spring-context-3.0.xsd

" >
<!--  使用注解支持事务  -->
< tx:annotation - driven transaction - manager = " transactionManager "   />
<!--  添加jdbc的任务管理器  -->
< bean  id = " transactionManager "   class = " org.springframework.jdbc.datasource.DataSourceTransactionManager " >
     < property name = " dataSource "  ref = " dataSource " ></ property >
</ bean >
< bean id = " dataSource "   class = " com.mchange.v2.c3p0.ComboPooledDataSource " >
< property name = " driverClass "   value = " com.mysql.jdbc.Driver " />
< property name = " jdbcUrl "   value = " jdbc:mysql:///mydb " />
< property name = " properties " >
< props >
     < prop key = " user " > root </ prop >
     < prop key = " password " > root </ prop >
    
</ props >
</ property >
</ bean >
< bean id = " simpleJdbcTemplate "    class = " org.springframework.jdbc.core.simple.SimpleJdbcTemplate " >
     < constructor - arg ref = " dataSource " ></ constructor - arg >
</ bean >
<!--  在使用事务时不能配置jdbc模板，只能配置数据流  -->
< bean  id = " userdao "   class = " com.yjw.dao.UserDao " >
     < property name = " dataSource "  ref = " dataSource " ></ property >
</ bean >
< bean id = " userService "    class = " com.yjw.service.UserService " >
     <!--  name的值只和set方法后面的有关，要一样  -->
     < property name = " dao "   ref = " userdao " ></ property >
</ bean >
</ beans > 在service里加：
// 在类的头上加上这个注解，代表这个类的所有方法都加上了事务，
// 作用是某个方法里的代码要么都执行，要么都不执行
// 默认是在发生RunTimeException是才回滚，发生Exception不回滚
// 加上(rollbackFor=Exception.class)表示所有的异常都回滚
@Transactional(rollbackFor = Exception. class )
public   class  UserService  {

    private  UserDao  userdao;
    
    

    public void setDao(UserDao userdao) {
        this.userdao = userdao;
    }
    
    public  void  save(User user){
        userdao.save(user);
    }
    //只读，会使性能提高，推荐使用
    @Transactional(readOnly=true)
    public  User findById(int id){
        return userdao.findById(id);
    }
}