如何将已检查的异常从 CompletableFuture 传递给 ControllerAdvice

Question

如何让 controllerAdvice class 捕获从 completablefuture 抛出的异常。在下面的代码中，我有一个方法 checkId 会引发已检查的异常。我使用 completablefuture 调用此方法并将已检查的异常包装在 CompletionException 中。虽然我在控制器建议中有一个处理程序方法class，但它没有处理错误。

package com.example.demo.controller;
@RestController
public class HomeController {

    @GetMapping(path = "/check")
    public CompletableFuture<String> check(@RequestParam("id") int id) {
        return CompletableFuture.supplyAsync(() -> {
            try {
                return checkId(id);
            }
            catch (Exception e) {
                throw new CompletionException(e);
            }
        });
    }

    public String checkId(int id) throws Exception  {
        if (id < 0) {
            throw new MyException("Id must be greater than 0");
        }
        return "id is good";
    }

}

-

package com.example.demo;
public class MyException extends Exception {

    public MyException(String message) {
        super(message);
    }

}

-

package com.example.demo;
@ControllerAdvice
public class ExceptionResolver {

    @ExceptionHandler(value = CompletionException.class)
    public String handleCompletionException(CompletionException ex) {
        return ex.getMessage();
    }

}

--

package com.example.demo;
@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

}

堆栈跟踪：

com.example.demo.MyException: Id must be greater than 0
    at com.example.demo.controller.HomeController.checkId(HomeController.java:30) ~[classes/:na]
    at com.example.demo.controller.HomeController.lambda[=14=](HomeController.java:19) ~[classes/:na]
    at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1700) ~[na:na]
    at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1692) ~[na:na]
    at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290) ~[na:na]
    at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020) ~[na:na]
    at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656) ~[na:na]
    at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594) ~[na:na]
    at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:177) ~[na:na]

2020-01-24 14:38:30.489 ERROR 938 --- [nio-8080-exec-1] o.a.c.c.C.[.[.[/].[dispatcherServlet]    : Servlet.service() for servlet [dispatcherServlet] in context with path [] threw exception [Request processing failed; nested exception is com.example.demo.MyException: Id must be greater than 0] with root cause

com.example.demo.MyException: Id must be greater than 0
    at com.example.demo.controller.HomeController.checkId(HomeController.java:30) ~[classes/:na]
    at com.example.demo.controller.HomeController.lambda[=14=](HomeController.java:19) ~[classes/:na]
    at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1700) ~[na:na]
    at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.exec(CompletableFuture.java:1692) ~[na:na]
    at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:290) ~[na:na]
    at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1020) ~[na:na]
    at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1656) ~[na:na]
    at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1594) ~[na:na]
    at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:177) ~[na:na]

Answer 1

@Deadpool 和我能够找出问题所在。

在 completableFuture 代码的 catch 块内，异常被包装在 CompletionException 异常中，这是一个运行时间异常。当端点被命中时，CompletionException 异常在某个时候被解包为类型为 MyException 的原始异常（已检查的异常）。这意味着处理程序方法应该处理 MyException 类型的异常，而不是 CompletionException.

@ExceptionHandler(value = MyException.class)
@ResponseBody 
public String handleCompletionException(MyException ex) { 
     return ex.getMessage(); 
}

如何将已检查的异常从 CompletableFuture 传递给 ControllerAdvice

How to pass checked exception from CompletableFuture to ControllerAdvice

java

spring

java-8

completable-future

controller-advice