如何在android中动态启动和完成progressBar答案

【问题标题】：How to start and finish progressBar dynamically in android如何在android中动态启动和完成progressBar
【发布时间】：2011-05-27 09:57:15
【问题描述】：

当我从第一个活动类中跳过第二个活动类时，我将在第二个活动中对某个图像开始图像处理，然后直到新图像出现在屏幕上，我不想启动进度条，然后在新图像出现在屏幕上时完成。我该怎么做？

【问题讨论】：

标签： android android-layout android-widget progress-bar

【解决方案1】：

使用 ProgreaaDialog 和 AsyncTask。你会得到你的灵魂在 doBackInGroundProcess 中使用 AsyncTask 进行图像处理。并在 doPostExecute() 中退出或取消进度对话框

查看示例代码。要启动 AsyncTsk，请在要进行图像处理的活动中使用 new ProgressTask().execute(null);。

    private class ProgressTask extends AsyncTask<String, Void, Boolean> {
        private ProgressDialog dialog;
        List<Message> titles;
        private ListActivity activity;
        //private List<Message> messages;
        public ProgressTask(ListActivity activity) {
            this.activity = activity;
            context = activity;
            dialog = new ProgressDialog(context);
        }



        /** progress dialog to show user that the backup is processing. */

        /** application context. */
        private Context context;

        protected void onPreExecute() {
            this.dialog.setMessage("Progress start");
            this.dialog.show();
        }

            @Override
        protected void onPostExecute(final Boolean success) {
                List<Message> titles = new ArrayList<Message>(messages.size());
                for (Message msg : messages){
                    titles.add(msg);
                }
                MessageListAdapter adapter = new MessageListAdapter(activity, titles);
                activity.setListAdapter(adapter);
                adapter.notifyDataSetChanged();

                if (dialog.isShowing()) {
                dialog.dismiss();
            }

            if (success) {
                Toast.makeText(context, "OK", Toast.LENGTH_LONG).show();
            } else {
                Toast.makeText(context, "Error", Toast.LENGTH_LONG).show();
            }
        }

        protected Boolean doInBackground(final String... args) {
            try{    
                BaseFeedParser parser = new BaseFeedParser();
                messages = parser.parse();


                return true;
             } catch (Exception e){
                Log.e("tag", "error", e);
                return false;
             }
          }


    }

}

有一个look here

【讨论】：

【解决方案2】：

尝试使用如下所示的异步任务：

try{
class test extends AsyncTask{


     TextView tv_per;
     int mprogress;

    Dialog UpdateDialog = new Dialog(ClassContext);

    @Override
    protected void onPreExecute() {
        // TODO Auto-generated method stub
        mprogress = 0;

        UpdateDialog.setTitle(getResources().getString(R.string.app_name));
        UpdateDialog.setContentView(R.layout.horizontalprogressdialog);
        TextView dialog_message =  (TextView)UpdateDialog.findViewById(R.id.titleTvLeft);
        tv_per = (TextView)UpdateDialog.findViewById(R.id.hpd_tv_percentage);
        dialog_message.setText(getResources().getString(R.string.dialog_retrieving_data));
        dialog_message.setGravity(Gravity.RIGHT);
        UpdateDialog.setCancelable(false);
        UpdateDialog.show();
        super.onPreExecute();
    }



    @Override
    protected void onProgressUpdate(Object... values) {
        // TODO Auto-generated method stub
        ProgressBar update = (ProgressBar)UpdateDialog.findViewById(R.id.horizontalProgressBar);
        update.setProgress((Integer) values[0]);
        int percent =  (Integer) values[0];
        if(percent>=100)
        {
            percent=100;
        }
        tv_per = (TextView)UpdateDialog.findViewById(R.id.hpd_tv_percentage);
         tv_per.setText(""+percent);
    }



    @Override
    protected Object doInBackground(Object... params) {
        // TODO Auto-generated method stub
        //your code
}

        super.onPostExecute(result);
        UpdateDialog.dismiss();
    }

 }
 new test().execute(null);

 }
catch(Exception e)
{
 e.printStackTrace();
}

【讨论】：

【解决方案3】：

这是一个在调用时启动进度条的方法

private void downloadText(String urlStr) {

    final String url = urlStr;
     progressDialog = ProgressDialog.show(this, "", "Trying to register...");
    Log.i("First string", urlStr);
try{
    new Thread () {
        public void run() {
            int BUFFER_SIZE = 2000;
            InputStream in = null;
            try{
           msg = Message.obtain();
            msg.what=1;
            }catch(Exception e)
            {
            }

            try {
                in = openHttpConnection(url);
           InputStreamReader isr = new InputStreamReader(in);
                int charRead;
                  text = "";
                  char[] inputBuffer = new char[BUFFER_SIZE];

                      while ((charRead = isr.read(inputBuffer))>0)
                      {                    
                          //---convert the chars to a String---
                          String readString = 
                          String.copyValueOf(inputBuffer, 0, charRead);                    
                          text += readString;
                          inputBuffer = new char[BUFFER_SIZE];
                      }
                     Bundle b = new Bundle();
                        b.putString("text", text);
                        msg.setData(b);
                      in.close();

            }catch (Exception e) {

            //////////////////////////////////////  
                e.printStackTrace();
            }
            try{
            messageHandler.sendMessage(msg);
            }catch(Exception e)
            {
            }
        }
    }.start();
}catch(Exception e)
{

}

}

这是处理程序代码

private Handler messageHandler = new Handler() {


    public void handleMessage(Message msg) {
        try{
        super.handleMessage(msg);
        switch (msg.what) {

        case 1:

{ 休息; } } progressDialog.dismiss(); }catch（异常 e） {

【讨论】：

【解决方案4】：

试试这个方法首先初始化你的 ProgressDialog

 progressDialog = ProgressDialog.show(this, "", "Trying to ...");

然后启动一个新线程，您可以在其中编写需要执行的代码最后在处理程序中处理代码并结束progessDialog

【讨论】：