Display progress bar while loading

问题:

I have one button in the main.xml which will link to another xml which include information from server. I include progress bar to avoid the blank screen while the system is loading the information. i already done the code as below but it's still not the things i wanted. the code below will "WAIT" for 1000 ms then only will execute the next code. how can i modify it so that the loading "WAIT TIME" will depends on the internet speed, if internet connection is slow, then the progress-bar-screen will show longer.

package com.android.myApps;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.view.View;
import android.widget.TextView;

public class MainScr extends Activity {

    private final int WAIT_TIME = 1000;

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {       
        super.onCreate(savedInstanceState);     
        setContentView(R.layout.MainScr);       
    }   

    public void onClickCategory(View view)
    {
        findViewById(R.id.mainSpinner1).setVisibility(View.VISIBLE);
        new Handler().postDelayed(new Runnable(){
            @Override
                public void run() {                          
                      Intent mainIntent = new Intent(MainScr.this, Category.class); 
                      MainScr.this.startActivity(mainIntent); 
                      MainScr.this.finish(); 
                      } 
            }, WAIT_TIME);
    }
}

回答1:

The mistake you are doing here is you are dumping specific time into your code You never know how much it will take to get response. You should follow following approach

Step 1 Show progress dialog on screen

Step 2 Let download take its own time.But it should be done in new thread

Step 3 Once download is complete it will raise message that task is done,now remove that progress dialog and proceed.

I am pasting sample code here.Hope it will help you.

package com.android.myApps;

import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.Intent;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;

public class MainScr extends Activity
{
    private Handler handler;
    private ProgressDialog progress;
    private Context context;

    @Override
    public void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        context = AncActivity.this;
        progress = new ProgressDialog(this);
        progress.setTitle("Please Wait!!");
        progress.setMessage("Wait!!");
        progress.setCancelable(false);
        progress.setProgressStyle(ProgressDialog.STYLE_SPINNER);

        handler = new Handler()
        {

            @Override
            public void handleMessage(Message msg)
            {
                progress.dismiss();
                Intent mainIntent = new Intent(context, Category.class);
                startActivity(mainIntent);
                super.handleMessage(msg);
            }

        };
        progress.show();
        new Thread()
        {
            public void run()
            {
                // Write Your Downloading logic here
                // at the end write this.
                handler.sendEmptyMessage(0);
            }

        }.start();

    }

}

回答2:

Did you try Asyntask? Your doing process will be update in UI.

public final class HttpTask
        extends
        AsyncTask<String/* Param */, Boolean /* Progress */, String /* Result */> {

    private HttpClient mHc = new DefaultHttpClient();

    @Override
    protected String doInBackground(String... params) {
        publishProgress(true);
        // Do the usual httpclient thing to get the result
        return result;
    }

    @Override
    protected void onProgressUpdate(Boolean... progress) {
        // line below coupled with 
        //    getWindow().requestFeature(Window.FEATURE_INDETERMINATE_PROGRESS) 
        //    before setContentView 
        // will show the wait animation on the top-right corner
        MyActivity.this.setProgressBarIndeterminateVisibility(progress[0]);
    }

    @Override
    protected void onPostExecute(String result) {
        publishProgress(false);
        // Do something with result in your activity
    }
}