我们在做Android开发的时候经常会遇到后台线程执行的比如说下载文件的时候,这个时候我们希望让客户能看到后台有操作进行，这时候我们就可以使用进度条,那么既然在后台运行,为的就是尽量不占用当前操作空间，用户可能还要进行其他操作,最好的方法就是在通知栏有个通知消息并且有个进度条。本文给一个例子工读者参考.
效果图如下：

主界面只有一个按钮就不上文件了

通知栏显示所用到的布局文件content_view.xml

<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:background="#00000000" android:orientation="vertical" android:padding="5dp"> <ImageView android:id="@+id/content_view_image" android:layout_width="25dp" android:layout_height="25dp" android:src="@drawable/logo" /> <TextView android:id="@+id/content_view_text1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="0%" android:textColor="#000000" android:layout_toRightOf="@id/content_view_image" android:layout_centerHorizontal="true" android:layout_marginTop="5dp" android:layout_marginLeft="15dp" /> <ProgressBar android:id="@+id/content_view_progress" android:layout_width="fill_parent" android:layout_height="wrap_content" style="@android:style/Widget.ProgressBar.Horizontal" android:max="100" android:layout_below="@id/content_view_image" android:layout_marginTop="4dp" /> </RelativeLayout>

主运行类：

package yyy.testandroid4; import java.util.Timer; import java.util.TimerTask; import android.app.Activity; import android.app.AlertDialog.Builder; import android.app.Notification; import android.app.NotificationManager; import android.app.PendingIntent; import android.content.DialogInterface; import android.content.Intent; import android.content.pm.PackageManager.NameNotFoundException; import android.os.Bundle; import android.os.Handler; import android.os.Message; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import android.widget.RemoteViews; import android.widget.Toast; public class TestAndroid4Activity extends Activity { private Handler handler = new Handler(){ @Override public void handleMessage(Message msg) { // TODO Auto-generated method stub super.handleMessage(msg); switch (msg.what) { case 0: notif.contentView.setTextViewText(R.id.content_view_text1, len+"%"); notif.contentView.setProgressBar(R.id.content_view_progress, 100, len, false); manager.notify(0, notif); break; case 1: Toast.makeText(TestAndroid4Activity.this, "下载完成", 0).show(); break; default: break; } } }; private Button update,cancel; private int localVersion,serverVersion; private int len; private NotificationManager manager; private Notification notif; /** Called when the activity is first created. */ @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); update = (Button) findViewById(R.id.update); update.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { // TODO Auto-generated method stub //点击通知栏后打开的activity Intent intent = new Intent(TestAndroid4Activity.this,OtherActivity.class); PendingIntent pIntent = PendingIntent.getActivity(TestAndroid4Activity.this, 0, intent, 0); manager = (NotificationManager) getSystemService(NOTIFICATION_SERVICE); notif = new Notification(); notif.icon = R.drawable.logo; notif.tickerText = "新通知"; //通知栏显示所用到的布局文件 notif.contentView = new RemoteViews(getPackageName(), R.layout.content_view); notif.contentIntent = pIntent; manager.notify(0, notif); new DownLoadThread().start(); } }); } } private class DownLoadThread extends Thread{ private Timer timer = new Timer(); @Override public void run() { // TODO Auto-generated method stub super.run(); timer.schedule(new TimerTask() { @Override public void run() { // TODO Auto-generated method stub Message msg = new Message(); msg.what = 0; msg.obj = len; handler.sendMessage(msg); if(len == 100){ timer.cancel(); handler.sendEmptyMessage(1); } } }, 0, 1000); len = 0; try { while(len < 100){ len++; Thread.sleep(1000); } } catch (InterruptedException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } }

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。