Spring retry基本使用
背景介绍
在实际工作过程中，重试是一个经常使用的手段。比如MQ发送消息失败，会采取重试手段，比如工程中使用RPC请求外部服务,可能因为网络
波动出现超时而采取重试手段......可以看见重试操作是非常常见的一种处理问题,系统设计的手段
而在之前我们项目中处理重拾操作依赖MQ自身的重试机制,但是这种机制不是很灵活,如果某些功能没有使用MQ的话,那么就不是那么方便了,而本文介绍的
Spring-Retry却能够以一种很优雅的方式解决这种问题,当然目前版本的Spring-retry还不是完美的,还是有待改进的.不过已经很不错了.
基本使用
例子1
@Configuration
@EnableRetry
public class Application {
@Bean
public Service service() {
return new Service();
}
}
@Service
class Service {
@Retryable(RemoteAccessException.class)
public void service() {
// ... do something
}
@Recover
public void recover(RemoteAccessException e) {
// ... panic
}
}
例子2
@org.springframework.stereotype.Service
public class Service1 {
@Retryable(value = {RemoteAccessException.class, RuntimeException.class},
maxAttempts = 2,
backoff = @Backoff(value = 2000))
public void service() {
System.out.println("do some things");
// this exception will just trigger recover1, do not trigger recover3
throw new RemoteAccessException("remote access exception");
// this exception will just trigger recover2
// throw new RuntimeException("runtime exception");
// System.out.println("do another things");
}
// 如果使用注解的话,这个recover貌似只能写在本类中,我测试了如果将recover方法写在
// recoverService中,好像找不到
@Recover
public void recover1(RemoteAccessException e) {
System.out.println(e.getMessage());
System.out.println("do recover operation1");
}
@Recover
public void recover2(RuntimeException e) {
System.out.println(e.getMessage());
System.out.println("do recover operation2");
}
@Recover
public void recover3(RemoteAccessException e) {
System.out.println(e.getMessage());
System.out.println("do recover operation3");
}
}
例子3
@Service
public class Service2 {
public void test(){
final RetryTemplate retryTemplate = new RetryTemplate();
final SimpleRetryPolicy policy = new SimpleRetryPolicy(3, Collections.<Class<? extends Throwable>, Boolean>
singletonMap(Exception.class, true));
FixedBackOffPolicy fixedBackOffPolicy = new FixedBackOffPolicy();
fixedBackOffPolicy.setBackOffPeriod(100);
retryTemplate.setRetryPolicy(policy);
retryTemplate.setBackOffPolicy(fixedBackOffPolicy);
final RetryCallback<Object, Exception> retryCallback = new RetryCallback<Object, Exception>() {
public Object doWithRetry(RetryContext context) throws Exception {
System.out.println("do some thing");
//设置context一些属性,给RecoveryCallback传递一些属性
context.setAttribute("key1", "value1");
System.out.println(context.getRetryCount());
throw new Exception("exception");
// return null;
}
};
// 如果RetryCallback执行出现指定异常, 并且超过最大重试次数依旧出现指定异常的话,就执行RecoveryCallback动作
final RecoveryCallback<Object> recoveryCallback = new RecoveryCallback<Object>() {
public Object recover(RetryContext context) throws Exception {
System.out.println("do recory operation");
System.out.println(context.getAttribute("key1"));
return null;
}
};
try {
final Object execute = retryTemplate.execute(retryCallback, recoveryCallback);
} catch (Exception e) {
e.printStackTrace();
}
}
}
参考资料
spring-retry
spring-retry-showcase
Spring retry – ways to integrate with your project
