android progressdialog 对话框试用实例

ProgressDialog 跟AlertDialog用法差不多,不同的是:ProgressDialog 显示的是一种"加载中"的效果,android 中 ProgressDialog 必须要在后台程序运行完毕前 使用dismiss()方法来关闭取得焦点(focus)的对话框,否则程序会陷入死循环.

试用:

package com.app.progressdialogtest;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.util.Log;
import android.view.Menu;
import android.view.Window;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity {
	private ProgressDialog dialog = null;
	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		// 1、不能将Activity布局设计为无标题,并在setContentView（）之前设置一下标题布局形式：
		requestWindowFeature(Window.FEATURE_INDETERMINATE_PROGRESS);
		setContentView(R.layout.activity_main);
		// setProgressBarIndeterminateVisibility(true);
		dialog = new ProgressDialog(this);
		// dialog =
		// ProgressDialog.show(getApplicationContext(),"请等待","网络加载中...",false);
		// dialog.setTitle("请等待..");
		dialog.setMessage("网络给力加载中...");
		// dialog.setIndeterminate(indeterminate);
		dialog.setCancelable(false);
		// dialog.setOnCancelListener(cancelListener);
		dialog.show();
		new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					getConnetction();
					Message msg = new Message();
					handler.sendMessage(msg);
					// setProgressBarIndeterminateVisibility(false);

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

	}
	Handler handler = new Handler() {
		public void handleMessage(Message msg) {
			// getConnetction();
			imageView.setImageBitmap(bitmap);
			dialog.dismiss();
		};
	};
	Bitmap bitmap;
	ImageView imageView;
	private void getConnetction() {
		String path = "http://www.baidu.com/img/baidu_jgylogo3.gif";
		Log.d("xxxxxx", "-");
		try {
			URL url = new URL(path);
			URLConnection connection = url.openConnection();
			InputStream inputStream = connection.getInputStream();
			bitmap = BitmapFactory.decodeStream(inputStream);
			imageView = (ImageView) findViewById(R.id.imageView1);
			// imageView.setImageBitmap(bitmap);
		} catch (MalformedURLException e) {
			Toast.makeText(getApplicationContext(), path + "error", 0).show();
			e.printStackTrace();
		} catch (IOException e) {
			Toast.makeText(getApplicationContext(), path + "connection error",
					0).show();
			e.printStackTrace();
		}
	}
}

简单应用:

在联网获取数据时，用一个进度条提示用户正在加载数据，。由于Android的界面更新只能通过自己的UI线程进行操作，所以我们需要用到Handler在进行更新界面的操作。

　   1、声明变量

    private Handler handler = new Handler();

    private ProgressDialog progressDialog = null;

　　2、在开始进行网络连接时显示进度条对话框

　　progressDialog = ProgressDialog.show(MyActivity.this, "请稍等...", "获取数据中...", true);

　　3、在handler.post中进行界面更新

  public void setListAdapter(){

  handler.post(new Runnable() {

  public void run() {

   //将获取到的数据更新到列表中

   MyListView.setAdapter(saImageItems);

    }

   }

   });

4、开个新的线程进行网络连接获取数据

    new Thread(new Runnable(){  

  @Override

    public void run() {

    // TODO Auto-generated method stub

    //向服务器请求数据

    mapList=MyAPI.getAllDatas();

    setListAdapter(mapList);

    //更新完列表数据，则关闭对话框

    progressDialog.dismiss();

    }}).start();

5.整个过程就这样了