Hystrix-異常處理

異常的傳播和捕獲

　　傳播：在HystrixCommand實現的run()方法中跑出異常時，除了HystrixBadRequestException之外，其他異常均會被Hystrix認為命令執行失敗並處罰服務降級的處理邏輯。下面的例子通過@HystrixCommand注解的ignoreException參數來設置。

　　捕獲：我們可以在降級方法中添加Throwable參數來捕獲異常。

package org.hope.hystrix.example.exception;

import com.netflix.hystrix.contrib.javanica.annotation.HystrixCommand;
import org.springframework.stereotype.Service;

@Service
public class HystrixHandleException {
    /**
     * 當設置ignoreExceptions參數時，
     * 拋出對應的異常就不會觸發降級(也就是不會調用failMethod()方法).
     */
    @HystrixCommand(
            ignoreExceptions = {NullPointerException.class, ArithmeticException.class},
            fallbackMethod = "failMethod"
                    )
    public String getUserName(Long id) {
        Long re = id/0; //會拋ArithmeticException
        String param = null;
        param.trim(); // 此處會拋NullPointException
        return "張三";
    }

    private String failMethod(Long id, Throwable e) {
        return e.getMessage();
    }



}

單元測試：

package org.hope.hystrix.example.exception;

import org.hope.hystrix.example.HystrixApplication;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@SpringBootTest(classes = HystrixApplication.class)
public class HystrixHandleExceptionTest {

    @Autowired
    private HystrixHandleException hystrixHandleException;
    @Test
    public void test() {
        String name = hystrixHandleException.getUserName(10L);
        System.out.println("==================" + name);
    }


}

 運行結果

java.lang.ArithmeticException: / by zero

    at org.hope.hystrix.example.exception.HystrixHandleException.getUserName(HystrixHandleException.java:20)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at com.netflix.hystrix.contrib.javanica.command.MethodExecutionAction.execute(MethodExecutionAction.java:116)
    at com.netflix.hystrix.contrib.javanica.command.MethodExecutionAction.executeWithArgs(MethodExecutionAction.java:93)
    at com.netflix.hystrix.contrib.javanica.command.MethodExecutionAction.execute(MethodExecutionAction.java:78)
    at com.netflix.hystrix.contrib.javanica.command.GenericCommand$1.execute(GenericCommand.java:48)
    at com.netflix.hystrix.contrib.javanica.command.AbstractHystrixCommand.process(AbstractHystrixCommand.java:145)
    at com.netflix.hystrix.contrib.javanica.command.GenericCommand.run(GenericCommand.java:45)
    at com.netflix.hystrix.HystrixCommand$2.call(HystrixCommand.java:302)
    at com.netflix.hystrix.HystrixCommand$2.call(HystrixCommand.java:298)
    at rx.internal.operators.OnSubscribeDefer.call(OnSubscribeDefer.java:46)

 

 

 

 

 

 

 

參考：

[1]Github，https://github.com/Netflix/Hystrix/wiki/How-it-Works

[2] 《SpringCloud微服務實戰》，電子工業出版社，翟永超