orService executor = Executors.newCachedThreadPool();
//Future
Future<String> future = executor.submit(taskCall);
System.out.println(future.get());
//FutureTask
executor.submit(futureTaskCall);
System.out.println(futureTaskCall.get());
//FutureTask自定义线程执行
new Thread(futureTaskRun).start();
System.out.println(futureTaskRun.get());
public class FutureTaskJobCallable implements Callable<String>{
public String call() throws Exception {
System.out.println("FutureTaskJobCallable已经执行了哦");
Thread.sleep(1000);
return "返回结果";
}
}
public class FutureTaskJobRunnable implements Runnable {
public void run() {
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
System.out.println("FutureTaskJobRunnable已经执行了哦");
}
}
根据上面的代码我们从ExecutorService接口中submit方法入手,看下AbstractExecutorService类对submit方法的具体实现。
public Future<?> submit(Runnable task) {
if (task == null) throw new NullPointerException();
RunnableFuture<Void> ftask = newTaskFor(task, null);
execute(ftask);
return ftask;
}
public <T> Future<T> submit(Runnable task, T result) {
if (task == null) throw new NullPointerException();
RunnableFuture<T> ftask = newTaskFor(task, result);
execute(ftask);
return ftask;
}
public <T> Future<T> submit(Callable<T> task) {
if (task == null) throw new NullPointerException();
RunnableFuture<T> ftask = newTaskFor(task);
execute(ftask);
return ftask;
}
protected <T> RunnableFuture<T> newTaskFor(Runnable runnable, T value) {
return new FutureTask<T>(runnable, value);
}
protected <T> RunnableFuture<T> newTaskFor(Callable<T> callable) {
return new FutureTask<T>(callable);
}
可以看到当你使用submit方法提交任务时,都会通过newTaskFor方法转换成FutureTask对象,所以我们具体分析下上面代码中的三种情况:
1、如果你传入的是自己实现的Runaable类或者Callable类,那么sumbit方法自然会帮你自动封装为FutureTask对象,运行后通过Future对象获取结果。
2、你传入的已经是个自己构造的FutureTask对象,由于FutureTask其实是实现了Runnable接口的,它本身就是个Runaable实现类, sumbit方法还是会将它视为Runnable类来进行封装,并最终会执行FutureTask自己的run方法,一系列实现都在你传入的FutureTask对象内完成,所以你可以直接通过自己构建的