指向仅显示进度对话框的活动的startActivityForResult

Question

我正在尝试做一个被要求得到一些结果的活动。这个结果通常是立即返回的(在onCreate中)，然而，有时需要等待一些互联网内容下载，这会导致“加载器”-activity显示。我想要的是loader-activity不显示任何东西，只显示一个进度对话框(并且您仍然可以在后台看到调用loader-activity的旧活动)，我想知道这是否可能。

我现在使用的代码是：

//ListComicsActivity.java
public class ListComicsActivity extends Activity
{
    private static final int REQUEST_COMICS = 1;


    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.list_comics);

        Button button = (Button)findViewById(R.id.Button01);
        button.setOnClickListener(new OnClickListener()
        {

            @Override
            public void onClick(View v) {
                Intent intent = new Intent();
                intent.setAction(Intents.ACTION_GET_COMICS);
                startActivityForResult(intent, REQUEST_COMICS);
            }
        });
    }

    /** Called when an activity called by using startActivityForResult finishes. */
    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data)
    {
        Toast toast = Toast.makeText(this, "The activity finnished", Toast.LENGTH_SHORT);
        toast.show();
    }
}


//LoaderActivity.java (answers to Intents.ACTION_GET_COMICS action-filter)
public class LoaderActivity extends Activity
{
    private Intent result = null;
    private ProgressDialog pg = null;
    private Runnable returner = new Runnable()
    {
        public void run()
        {
            if(pg != null)
                pg.dismiss();
            LoaderActivity.this.setResult(Activity.RESULT_OK, result);
            LoaderActivity.this.finish();
        }
    };

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);


        String action = getIntent().getAction();
        if(action.equals(Intents.ACTION_GET_COMICS))
        {
            Runnable loader = new Runnable()
            {
                public void run()
                {
                    WebProvider.DownloadComicList();
                    Intent intent = new Intent();
                    intent.setDataAndType(ComicContentProvider.COMIC_URI, "vnd.android.cursor.dir/vnd.mymir.comic");
                    returnResult(intent);
                }
            };
            pg = ProgressDialog.show(this, "Downloading", "Please wait, retrieving data....");
            Thread thread = new Thread(null, loader, "LoadComicList");
            thread.start();
        }
        else
        {
            setResult(Activity.RESULT_CANCELED);
            finish();
        }
    }

    private void returnResult(Intent intent)
    {
        result = intent;
        runOnUiThread(returner);
    }
}

Answer 1

事实证明，您可以通过将活动的theme-attribute设置为@android:style/Theme.Dialog并在活动的onCreate-method中调用this.setVisible(false);来完成此操作。