public void run() {
// 转调
sync.innerRun();
}
void innerRun() {
if (!compareAndSetState(READY, RUNNING))
return;
runner = Thread.currentThread();
if (getState() == RUNNING) { // recheck after setting thread
V result;
try {
// 就是调用了mWorker.call方法
// 把耗时操作得到的结果赋值给result
result = callable.call();
} catch (Throwable ex) {
setException(ex);
return;
}
// 转调了sync.innerSet(v);
set(result);
} else {
releaseShared(0); // cancel
}
}
mWorker = new WorkerRunnable<Params, Result>() {
public Result call() throws Exception {
Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
// 执行耗时操作 在子线程中执行
return doInBackground(mParams);
}
};
protected void set(V v) {
// 转调
sync.innerSet(v);
}
void innerSet(V v) {
for (;;) {
int s = getState();
if (s == RAN)
return;
if (s == CANCELLED) {
// aggressively release to set runner to null,
// in case we are racing with a cancel request
// that will try to interrupt runner
releaseShared(0);
return;
}
if (compareAndSetState(s, RAN)) {
result = v;
releaseShared(0);
// 调用了FutureTask的抽象方法
done();
return;
}
}
}
mFuture = new FutureTask<Result>(mWorker) {
@Override
protected void done() {
Message message;
Result result = null;
try {
// 转调了sync.innerGet()
result = get();
} catch (InterruptedException e) {
android.util.Log.w(LOG_TAG, e);
} catch (ExecutionException e) {
throw new RuntimeException("An error occured while executing doInBackground()",
e.getCause());
} catch (CancellationException e) {
message = sHandler.obtainMessage(MESSAGE_POST_CANCEL,
new AsyncTaskResult<Result>(AsyncTask.this, (Result[]) null));
message.sendToTarget();
return;
} catch (Throwable t) {
throw new RuntimeException("An error occured while executing "
+ "doInBackground()", t);
}
// 发送了一个Message
message = sHandler.obtainMessage(MESSAGE_POST_RESULT,
new AsyncTaskResult<Result>(AsyncTask.this, result));
message.sendToTarget();
}
};
public V get() throws InterruptedException, ExecutionException {
// 转调
return sync.innerGet();
}
V innerGet() throws InterruptedException, ExecutionException {
acquireSharedInterruptibly(0);
if (getState() == CANCELLED)
throw new CancellationException();
if (exception != null)
throw new ExecutionException(exception);
// 把之前doinBackground方法的结果返回
return result;
}