java怎么拦截某个对象
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2022-11-04
SpringCloud之Hystrix的详细使用
SpringCloud之Hystrix的详细使用
目录***一.服务降级***2.不使用Hystrix的项目3. 使用Hystrix4. 全局的Hystrix配置 ***二.服务熔断***1.熔断机制概述2.项目中使用
1.概念
服务降级：服务器繁忙，请稍后再试，不让客户端等待，并立即返回一个友好的提示（一般发生在 程序异常，超时，服务熔断触发服务降级，线程池、信号量 打满也会导致服务降级）服务熔断 ： 达到最大服务访问后，直接拒绝访问，然后调用服务降级的方法并返回友好提示（如保险丝一样）服务限流 ： 秒杀等高并发操作，严禁一窝蜂的过来拥挤，排队进入，一秒钟N个，有序进行
***一.服务降级***
2.不使用Hystrix的项目
大致的Service和Controller层如下
***************Controller*****************
package com.sky.springcloud.controller;
import com.sky.springcloud.service.PaymentService;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;
import javax.annotation.Resource;
@RestController
@Slf4j
public class PaymentController {
@Resource
private PaymentService paymentService;
@Value("${server.port}")
private String serverport;
@GetMapping("/payment/hystrix/ok/{id}")
public String paymentInfo_Ok(@PathVariable("id") Integer id){
String result = paymentService.paymentInfo_ok(id);
log.info("*****"+ result);
return result;
}
@GetMapping("/payment/hystrix/timeout/{id}")
public String paymentInfo_TimeOut(@PathVariable("id") Integer id){
String result = paymentService.payment_Info_TimeOut(id);
}
*******************Service********************
package com.sky.springcloud.service;
import org.springframework.stereotype.Service;
import java.util.concurrent.TimeUnit;
@Service
public class PaymentServiceImpl implements PaymentService{
@Override
public String paymentInfo_ok(Integer id) {
return "线程池：" + Thread.currentThread().getName() + "paymentInfo_Ok. id:" + id + "\t" + "~~~~~";
public String payment_Info_TimeOut(Integer id) {
try {
TimeUnit.SECONDS.sleep(5);
} catch (InterruptedException e) {
e.printStackTrace();
}
return "线程池：" + Thread.currentThread().getName() + "paymentInfo_TimeOut. id:" + id + "\t" + "~~~~~";
在这种情况时,当通过浏览器访问 TimeOut这个方法,会三秒后返回结果,而当访问 OK 这个方法时,会直接返回结果(但是这是在访问量很少的时候,一旦访问量过多,访问OK时也会出现延迟,这里可以使用Jmeter模拟两万个访问量,如下)
使用 Jmeter 模拟后,再去访问OK,会明显出现加载的效果
3. 使用Hystrix
在主启动类添加注解@EnableHystrix
package com.sky.springcloud;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.cloud.netflix.eureka.EnableEurekaClient;
import org.springframework.cloud.netflix.hystrix.EnableHystrix;
@SpringBootApplication
@EnableEurekaClient //启用Eureka
@EnableHystrix //启用Hystrix
public class Payment8001 {
public static void main(String[] args) {
SpringApplication.run(Payment8001.class,args);
}
}
在原有的基础上,在Service层加上如下注解
@HystrixCommand(fallbackMethod = "payment_Info_TimeOutHandler",//当服务降级时,调用payment_Info_TimeOutHandler方法
commandProperties = {
@HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",
value = "3000")//设置时间为3秒,超过三秒就为时间超限
*****************改后的Service*******************
package com.sky.springcloud.service;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.stereotype.Service;
import java.util.concurrent.TimeUnit;
@Service
public class PaymentServiceImpl implements PaymentService{
@Override
public String paymentInfo_ok(Integer id) {
return "线程池：" + Thread.currentThread().getName() + "paymentInfo_Ok. id:" + id + "\t" + "~~~~~";
}
@HystrixCommand(fallbackMethod = "payment_Info_TimeOutHandler",commandProperties = {
@HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",value = "3000")
})
public String payment_Info_TimeOApqAkXgut(Integer id) {
ApqAkXgtry {
TimeUnit.SECONDS.sleep(5);
} catch (InterruptedException e) {
e.printStackTrace();
}
// int a = 10 / 0;
return "线程池：" + Thread.currentThread().getName() + "paymentInfo_TimeOut. id:" + id + "\t" + "~~~~~";
}
public String payment_Info_TimeOutHandler(Integer id){
return "线程超时或异常 " + Thread.currentThread().getName();
}
}
如上Service所示,如果再次访问TimeOut需要等待五秒,但是Hystrix设置的超时时间为三秒,所以当三秒后没有结果就会服务降级,从而调用TimeOutHandler这个指定 的方法来执行(或者有程序出错等情况也会服务降级)
4. 全局的Hystrix配置
@DefaultProperties(defaultFallback = “Gloub_Test”)
package com.sky.springcloud.service;
import com.netflix.hystrix.contrib.javanica.annotation.DefaultProperties;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import com.netflix.hystrix.contrib.javanica.annotation.HystrixProperty;
import org.springframework.stereotype.Service;
@Service
@DefaultProperties(defaultFallback = "Gloub_Test")
public class PaymentServiceImpl implements PaymentService{
@Override
@HystrixCommand
public String paymentInfo_ok(Integer id) {
int a = 10 / 0;
return "线程池：" + Thread.currentThread().getName() + "paymentInfo_Ok. id:" + id + "\t" + "~~~~~";
}
@HystrixCommand(fallbackMethod = "payment_Info_TimeOutHandler",commandProperties = {
@HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds",value = ApqAkXg"3000")
})
public String payment_Info_TimeOut(Integer id) {
/* try {
TimeUnit.SECONDS.sleep(5);
} catch (InterruptedException e) {
e.printStackTrace();
}*/
return "线程池：" + Thread.currentThread().getName() + "paymentInfo_TimeOut. id:" + id + "\t" + "~~~~~";
public String payment_Info_TimeOutHandler(Integer id){
return "线程超时或异常 " + Thread.currentThread().getName();
public String Gloub_Test(){
return "走了全局的";
}
如上Service所示,加了@HystrixCommand的方法里,如果没指定fallbackMethod 就会默认去找全局的defaultFallback这里 当paymentInfo_ok 方法出错时,会调用Gloub_Test方法当payment_Info_TimeOut出错时,会调用payment_Info_TimeOutHandler方法
***二.服务熔断***
1.熔断机制概述
熔断机制是应对雪崩效应的一种微服务链路保护机制,当扇出链路的某个微服务出错不可用或者响应时间太长,会进行服务的降级,进而熔断该节点微服务的调用,快速返回错误的相应信息.当检测到该节点微服务调用相应正常后,恢复调用链路.
2.项目中使用
在上面的基础上,改写Service和Controller(添加以下代码)
//是否开启服务熔断(断路器)
@HystrixProperty(name = "circuitBreaker.enabled",value = "true"),
//服务请求的次数
@HystrixProperty(name = "circuitBreaker.requestVolumeThreshold",value = "10"),
//时间的窗口期
@HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds", value = "10000"),
//当失败率达到多少后发生熔断
@HystrixProperty(name = "circuitBreaker.errorThresholdPercentage",value = "60"),
******************Service*****************
@HystrixCommand(fallbackMethod = "paymentCircuitBreaker_fallback",
commandProperties = {
@HystrixProperty(name = "circuitBreaker.enabled",value = "true"),
@HystrixProperty(name = "circuitBreaker.requestVolumeThreshold",value = "10"),
@HystrixProperty(name = "circuitBreaker.sleepWindowInMilliseconds", value = "10000"),
@HystrixProperty(name = "circuitBreaker.errorThresholdPercentage",value = "60"),
})
public String PaymentCircuitBreaker(@PathVariable("id") Integer id){
if(id<0){
throw new RuntimeException("********** id不能为负");
}
String serialNumber = IdUtil.simpleUUID();
return Thread.currentThread().getName() + "\t" + serialNumber;
}
public String paymentCircuitBreaker_fallback(@PathVariable("id") Integer id){
return "id 不能为负:" + id;
************Controller********************
@GetMapping("/payment/circuit/{id}")
String result = paymentService.PaymentCircuitBreaker(id);
log.info(result + "***********");
return result;
如上所示,当访问paymentCircuitBreaker时,如果id小于零则会有一个运行错误,这时候就会通过服务降级来调用paymentCircuitBreaker_fallback方法,当错误的次数达到60%的时候(自己设的),就会出现服务熔断,这个时候再访问id大于零的情况,也会发生服务降级,因为开起了服务熔断,需要慢慢的恢复正常.
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