嵌套异常是java.util.concurrent.executionException

Question

我正在获取dynamo db中的所有记录，对于每条记录，我都要对一个外部服务进行多线程调用。

但是我得到了这个错误：

嵌套异常是java.util.concurrent.executionException:org.springframework.web.client.HttpServererRoreXception:500 null]

@Autowired
public RestTemplate restTemplate;

@Autowired
public MyCallable myCallable;
@GetMapping("/myApp-multithread")
public String getQuoteOnSepThread() throws InterruptedException, ExecutionException {
    System.out.println("#################################################Multi Threaded Post Call######################");
    ExecutorService executor= Executors.newFixedThreadPool(10);
    List<Future<String>> myFutureList= new ArrayList<Future<String>>();
    long startTime=System.currentTimeMillis()/1000;

    Iterable<Customer> customerIterable=repo.findAll();
    List<Customer> customers=new ArrayList<Customer>();
    customerIterable.forEach(customers::add);


    for(Customer c:customers) {

        myCallable.sendCustomerToInterface(c);
        //System.out.println(c);
        Future<String> future= executor.submit(myCallable);
        myFutureList.add(future);

    }

    for(Future<String> fut:myFutureList) {
        fut.get();
    }
    executor.shutdown();

    long timeElapsed= (System.currentTimeMillis()/1000)-startTime;

    System.out.println("->>>>>>>>>>>>>>>Time Elapsed In Multi Threaded Post Call<<<<<<<<<<<<<<<-"+timeElapsed);
    return "Success";

}

public class MyCallable implements Callable<String>{

@Autowired
public RestTemplate restTemplate;

//int index=-1;

Customer c= c= new Customer();;
public void sendCustomerToInterface(Customer cust) {

    c= cust;
}

@Override
public String call() throws Exception {

    System.out.println("Customer no"+ c.getId() +"On thread Number"+Thread.currentThread().getId());
    return restTemplate.postForObject("http://localhost:3000/save", c, String.class);

}

}

编辑：

错误的完整堆栈跟踪：

org.springframework.web.client.httpserverroreXception:500 null at org.springframework.web.client.defaultresponseerrorhandler.handleerror(defaultresponseerrorhandler.java:88)~[spring-web-4.3.13.release.jar:4.3.13.release]at org.springframework.web.client.resttemplate.handleresponse ase.jar:4.3.13.发布]在org.springframework.web.client.resttemplate.execute(resttemplate.java:620)~[spring-web-4.3.13.release.jar:4.3.13.发布]在org.springframework.web.client.resttemplate.postforObject(resttemplate.java:387)~[spring-web-4.3.13.release]在com.ocademoclient.ocademoclient.mycallable.call~[classes/:na]在java.util.concurrent.futureTask.run(FutureTask.java:266)~[na:1.8.0_181]在java.util.concurrent.threadpoolexecutor.java:1149)~[na:1.8.0_181]at java.util.concurrent.threadpoolexecutor$worker.run(threadpoolexecutor.java:624)~[na:1.8.0_181]at java.lang.thread.run(thread.java:748)[na:1.8.0_181]

Answer 1

根据Javadoc：

试图检索通过引发异常而中止的任务的结果时引发的异常。

问题似乎是，对于一些客户

    restTemplate.postForObject("http://localhost:3000/save", c, String.class);

这是行不通的，因为您的MyCallable是一个有状态对象（它使用void sendCustomerToInterface（Customer cust)存储Customer存储Customer，并且需要稍后在Call()方法中检索这个特定的Customer）。

要使其工作，可以重写MyCallable，如下所示：

public class MyCallable implements Callable<String>{

    private RestTemplate restTemplate;
    private Customer c;

    public MyCallable(RestTemplate rt, Customer cust) {
        this.restTemplate = rt;
        this.c = cust;
    }

    @Override
    public String call() throws Exception {
        System.out.println("Customer no"+ c.getId() +"On thread Number"+Thread.currentThread().getId());
        return restTemplate.postForObject("http://localhost:3000/save", c, String.class);

    }
}

在控制器中编写

for(Customer c:customers) {

    MyCallable myCallable = new MyCallable(restTemplate, c);
    //System.out.println(c);
    Future<String> future= executor.submit(myCallable);
    myFutureList.add(future);

}

for (Customer c: repo.findAll()) {
    //...
}