Spring Async 实现 ForkJoin

第一种情况,Service类:

@Async
public String test1() {
    String threadName = Thread.currentThread().getName();
    log.error("{}: 1 start", threadName);
    try {
        Thread.sleep(5000L);
    } catch (Exception e){
    }
    log.error("{}: 1 end", threadName);
    return "s1";
}

@Async
public String test2() {
    String threadName = Thread.currentThread().getName();
    log.error("{}: 2 start", threadName);
    try {
        Thread.sleep(2000L);
    } catch (Exception e){
    }
    log.error("{}: 2 end", threadName);
    return "s2";
}

Controller类:

try {
    String threadName = Thread.currentThread().getName();
    log.error("{}: 0 start", threadName);
    PrintWriter out = response.getWriter();
    String f1 = testService.test1();
    String f2 = testService.test2();
    log.error("{}: 0 end {} {}", threadName, f1, f2);

} catch (Exception e) {
}

 

结果是,test1和test2在不同线程被执行,然而对test1和test2的调用,立刻结束,f1和f2都是null。

也就是说,这样可以独立执行两个后台任务,然而并不能等待返回结果,怎样才能得到结果呢?

 

第二种情况,Service类:

@Async
public Future<String> test1() {
    String threadName = Thread.currentThread().getName();
    log.error("{}: 1 start", threadName);
    try {
        Thread.sleep(5000L);
    } catch (Exception e){
    }
    log.error("{}: 1 end", threadName);
    return new AsyncResult<>("s1");
}

@Async
public Future<String> test2() {
    String threadName = Thread.currentThread().getName();
    log.error("{}: 2 start", threadName);
    try {
        Thread.sleep(2000L);
    } catch (Exception e){
    }
    log.error("{}: 2 end", threadName);
    return new AsyncResult<>("s2");
}

 

Controller类:

try {
    String threadName = Thread.currentThread().getName();
    log.error("{}: 0 start", threadName);
    PrintWriter out = response.getWriter();
    Future<String> f1 = testService.test1();
    Future<String> f2 = testService.test2();
    
    log.error("{}: 0 end {} {}", threadName, f1.get(), f2.get());
} catch (Exception e) {
}

这样可以正确得到结果。Futrue<T>和AsyncResult<T>让调用线程可以join,等待Future结果。

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