Question

我在java程序中编写了许多异步未来任务调用。提供一个样本

FutureTask<List<ConditionFact>> x = getConditionFacts(final Member member);
FutureTask<List<RiskFact>> x = getRiskFacts(final Member member);
FutureTask<List<SAEFact>> x = getSAEFacts(final Member member);

现在假设我故意在上面的第二个调用中创建一个异常，并在一个try / catch块中包含所有3个调用get（）我没有看到异常来捕获块而我的java程序只是静止不动。所有3个方法调用都同时发生。

try {   
FutureTask<List<ConditionFact>> task = getConditionFacts(member);
        // wait for the task to complete and get the result:

            List<ConditionFact> conditionFacts = task.get();

      FutureTask<List<ConditionFact>> task = getRiskFacts(member);
        // wait for the task to complete and get the result:

            List<RiskFact> conditionFacts = task.get();
        }
        catch (ExecutionException e) {
            // an exception occurred.
            Throwable cause = e.getCause(); // cause is the original exception thrown by the DAO
        }

但是如果我将每个get（）包含在单独的try catch块中，我就可以捕获它们。为什么？此外，当我开始在try catch块中包含每个get（）方法时，我失去了多线程。方法调用逐个进行编码

      FutureTask<List<ConditionFact>> task = getConditionFacts(member);
    // wait for the task to complete and get the result:
    try {
        List<ConditionFact> conditionFacts = task.get();
    }
    catch (ExecutionException e) {
        // an exception occurred.
        Throwable cause = e.getCause(); // cause is the original exception thrown by the DAO
    }
  FutureTask<List<ConditionFact>> task = getRiskFacts(member);
    // wait for the task to complete and get the result:
    try {
        List<RiskFact> conditionFacts = task.get();
    }
    catch (ExecutionException e) {
        // an exception occurred.
        Throwable cause = e.getCause(); // cause is the original exception thrown by the DAO
    }

当我能够捕获异常时，我失去了多线程，当我能够生成多线程时，我失去了异常。

任何想法如何单独处理异常并同时实现多线程

Answer 1

我真的不喜欢这个。正确的答案是使用ExecutorService在线程池中运行任务。

ExecutorService executor = Executor.newFixedThreadPool(2);
FutureTask<List<ConditionFact>> task1 = getConditionFacts(member);
FutureTask<List<ConditionFact>> task2 = getRiskFacts(member);
executor.execute(task1);
executor.execute(task2);
// wait for the task to complete and get the result:
try {
    List<ConditionFact> conditionFacts = task1.get();
}
catch (ExecutionException e) {
    // an exception occurred.
    Throwable cause = e.getCause(); // cause is the original exception thrown by the DAO
}
// wait for the task to complete and get the result:
try {
    List<RiskFact> conditionFacts = task2.get();
}
catch (ExecutionException e) {
    // an exception occurred.
    Throwable cause = e.getCause(); // cause is the original exception thrown by the DAO
}

这将解决单线程执行问题。我在这里得到了答案：http://programmingexamples.wikidot.com/futuretask

Answer 2

ExecutorCompletionService应该有助于解决您的问题。您的代码需要实现队列机制来处理结果，ExecutorCompletionService应该有所帮助。看看吧。

未来任务异步调用在发生异常时挂起

2 个答案: