andriod多线程

用ThreadHandle可以实现多线程，然后再主线程更新UI

第二种就是用 

AsyncTask

具体看代码

public void onClick(View v) {
    new DownloadImageTask().execute("http://example.com/image.png");
}

private class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
    /** The system calls this to perform work in a worker thread and
      * delivers it the parameters given to AsyncTask.execute() */
    protected Bitmap doInBackground(String... urls) {
        return loadImageFromNetwork(urls[0]);
    }
    
    /** The system calls this to perform work in the UI thread and delivers
      * the result from doInBackground() */
    protected void onPostExecute(Bitmap result) {
        mImageView.setImageBitmap(result);
    }
}

主要是在另外一个线程工作的函数式doInBackground()，这个函数返回的值就是onPostExcute里面的参数

具体看如下官方文档

You should read the AsyncTask reference for a full understanding on how to use this class, but here is a quick overview of how it works:

• You can specify the type of the parameters, the progress values, and the final value of the task, using generics
• The method doInBackground() executes automatically on a worker thread
• onPreExecute(), onPostExecute(), and onProgressUpdate() are all invoked on the UI thread
• The value returned by doInBackground() is sent to onPostExecute()
• You can call publishProgress() at anytime in doInBackground() to execute onProgressUpdate() on the UI thread