使用Aysnc加载位图到对象

Question

我有一个问题，我试图从web api加载图像。我可以这样做，但是当我试图把它们放入对象的属性中时它就会崩溃。我看了所有的例子如何异步加载图像我能找到，但每个人我找到什么分配给一个imageview，而不是对象。

下面是调用代码 的示例

     Movie Example = new Movie();       
     DownloadImageTask task = new DownloadImageTask();
                String path = "http://d3gtl9l2a4fn1j.cloudfront.net/t/p/original" + example.getProfile_path();
                example.setProfile(task.execute(path).get());

这是我用来获取图像 的方法

private class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
    private ImageView bmImage;
    public DownloadImageTask() {
        this.bmImage = new ImageView(getActivity());
    }
    protected void onPreExecute() {
    }
    protected Bitmap doInBackground(String... urls) {
        try{
        URL url = new URL(urls[0]);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setDoInput(true);
        connection.connect();
        InputStream input = connection.getInputStream();
        Bitmap result = BitmapFactory.decodeStream(input);
        return result;
        } catch (IOException e) {
            e.printStackTrace();
            return null;
        }
    }
    protected void onPostExecute(Bitmap result) {
        //set image of your imageview
        try {
            bmImage.setImageBitmap(result);
            //close
        } catch (Exception ex) {
            Log.e("ERROR", "can't assign image to view");
        }
    }
}

我想要类似的东西，但不是分配给imageview它会返回图像给调用它的方法。

Answer 1

实际上，将图像返回给调用它的方法没有多大意义，因为该方法必须挂起自己并等待图像加载，这违背了让图像并行加载的目的。你到底想要完成什么?

如果你真的想这样做，我想它可以通过修改你的AsyncTask来完成，像这样:

private class DownloadImageTask extends AsyncTask<String, Void, Void> {
    private ImageView bmImage;
    private boolean finished = false;
    private Bitmap resultingBitmap = null;
    protected Void doInBackground(String... urls) {
        try{
        URL url = new URL(urls[0]);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setDoInput(true);
        connection.connect();
        InputStream input = connection.getInputStream();
        resultingBitmap = BitmapFactory.decodeStream(input);
        } catch (IOException e) {
            e.printStackTrace();
        }
        finished = true;
    }
    public boolean isFinished() {
        return finished;
    }
    public Bitmap getResultingBitmap() {
        return resultingBitmap;
    }
}

呼叫者代码:

DownloadImageTask task = new DownloadImageTask();
String path = "http://d3gtl9l2a4fn1j.cloudfront.net/t/p/original" + example.getProfile_path();
while (!task.isFinished()) { } // this defeats the purpose of parallel execution
example.setProfile(task.execute(path).getResultingBitmap());

你可以按照@Brandon的回答来完成:

private class DownloadImageTask extends AsyncTask<String, Void, Bitmap> {
    Example example;
    public DownloadImageTask(Example example) {
        this.example = example;
    }
    (...)
    protected void onPostExecute(Bitmap result) {
        example.setProfile(result);
    }
}