AsyncTask与Activity.runOnUiThread()与Handler.post() [英] AsyncTask vs Activity.runOnUiThread() vs Handler.post()

问题描述

我正在研究大型应用程序的代码. UI中使用了3种异步模式，它们似乎都是等效的:

I'm studying the code of a large app. There are 3 asynchrony patterns used in the UI, all of them seem equivalent:

模式1，AsyncTask

new AsyncTask<X, Void, Z>() {  
    protected Boolean doInBackground(X... params) {  
        //background task  
    }  

    protected void onPostExecute(Z res) {  
        //UI callback  
    }  
}.execute();

模式2，Activity.runOnUiThread(Runnable)

new Thread() {  
    public void run() {  
        //background task  

        runOnUiThread(new Runnable() {  
            public void run() {  
                //UI callback  
            }  
        });  
    }  
}.start();

模式3，Handler.post(可运行)

new Thread() {  
    public void run() {  
        //background task  

        handler.post(new Runnable() {  
            public void run() {  
                //UI callback  
            }  
        });  
    }  
}.start();

问题:

• 我缺少的3种模式之间有何区别? (除了AsyncTask在具有后台优先级的预先存在的线程池上运行.)
• 在任何情况下都倾向于使用特定模式?

推荐答案

无论是可见的还是内部的，它们实际上都是Handler.

They are all really a Handler either visibly or internally.

AsyncTask#finish()是从Handler消息循环中调用的.

AsyncTask#finish() that calls onPostExecute() is called from a Handler message loop.

runOnUiThread()将Runnable发布到Handler.如果它是UI线程，则可运行对象将同步执行-这并不总是可取的.

runOnUiThread() posts the Runnable to a Handler if the current thread is not the UI thread. If it is the UI thread, the runnable is executed synchronously - this is not always desirable.

直接使用Handler可以为您提供低级控制，并且仅此一个.

Directly using a Handler gives you low level control and only that.

使用什么取决于您的特定要求.

What to use depends on your specific requirements.

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