首先请大家看一下下面的代码,大家觉得有问题吗?代码的期望是子事务遇到异常进行回滚,而父事务不受其影响,在外部调用addParent()后,大家觉这段代码能做到吗?先卖个关子,请大家继续往下看哦,不看的话,就可能错过啥了哦。
@Service
@Slf4j
public class UserService {
@Autowired
private UserMapper userMapper;
@Transactional
//子事务回滚,不影响父事务
public void addParent(){
try{
addOperatorRecord();
}catch (Exception e){
log.error("子事务出错了");
}
User user = new User();
user.setName("parent");
user.setAge(50);
userMapper.insert(user);
}
@Transactional(propagation = Propagation.REQUIRES_NEW)
public void addOperatorRecord(){
User user = new User();
user.setName("child");
user.setAge(28);
userMapper.insert(user);
throw new RuntimeException("child Transactional");
}
}
输出日志
数据库现象
什么,上面的代码代码居然没有起作用,咋回事?那接下来就给大家带来原理分析,这个主要是Spring的事务是实现依赖AOP,其最底层其实是JDK动态代理或cglib动态代理,就是在代理的方法中调用代理的方法,被动的另一方法会不起作用。下面给大家用JDK动态代理来模拟一下现象
1.先声明个接口
public interface TransactionalInterface {
void createTransactional();
void commitTransactional();
}
2.正常的实现类
public class TestTransactionalImpl implements TransactionalInterface{
@Override
public void createTransactional() {
System.out.println("===========createTransactional============");
commitTransactional();
}
@Override
public void commitTransactional() {
System.out.println("===========commitTransactional============");
}
}
3.代理的实现
public class ProxyTransactionalImpl implements InvocationHandler {
private TransactionalInterface target;
public ProxyTransactionalImpl(TransactionalInterface target) {
this.target = target;
}
public TransactionalInterface createProxy(){
return (TransactionalInterface)Proxy.newProxyInstance(ProxyTransactionalImpl.class.getClassLoader(),
new Class[] {TransactionalInterface.class},
this
);
}
@Override
public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
if(method.getName().startsWith("c")){
System.out.println("==============Proxy=================");
}
return method.invoke(target,args);
}
public static void main(String[] args){
TestTransactionalImpl testTransactional = new TestTransactionalImpl();
ProxyTransactionalImpl proxyTransactional = new ProxyTransactionalImpl(testTransactional);
TransactionalInterface proxy =proxyTransactional.createProxy();
proxy.createTransactional();
System.out.println("==============直接调用=============");
proxy.commitTransactional();
}
}
输出的现象
从图中可以看出代理类直接调用方法,代理是起作用的,如果在代理方法中调用代理方法,则是无效的
注意数据库的类型要是InnoDB,Spring默认回滚的异常是RuntimeException,如果需要回滚Exception异常可以设置@Transactional(rollbackFor=Exception.class)来解决问题
1.使用xxxService.xxx()方法的形式,也是把被调用的方法重新移到一个类里
2.如果一定想在同一个类中调用的话,可以使用getBean方式来调用
try{
UserService userService = (UserService) applicationContext.getBean("userService");
userService.addOperatorRecord();
}catch (Exception e){
log.error("子事务出错了");
}
User user = new User();
user.setName("parent");
user.setAge(50);
userMapper.insert(user);