效果：
代码直接在上一篇AsyncTask示例中做修改，布局跟上次一样，这里不贴了。
MainActivity:
package com.example.asynctaskdemo4;
import java.io.ByteArrayOutputStream;
import java.io.InputStream;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import android.app.Activity;
import android.app.Notification;
import android.app.NotificationManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.BitmapFactory.Options;
import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v4.app.NotificationCompat;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity implements OnClickListener
{
private static final String PATH = "http://h.hiphotos.baidu.com/image/w%3D2048/sign=d78504fa9d3df8dca63d8891f929738b/9f510fb30f2442a77e79f7a8d343ad4bd1130243.jpg";
private Button but_down = null;
private ImageView iv_show = null;
private TextView tv_progress = null;
private ProgressBar pb = null;
private NotificationManager manager = null;
private NotificationCompat.Builder builder;
@Override
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
but_down = (Button) findViewById(R.id.but_down);
iv_show = (ImageView) findViewById(R.id.iv_show);
tv_progress = (TextView) findViewById(R.id.tv_progress);
pb = (ProgressBar) findViewById(R.id.pb);
manager = (NotificationManager) MainActivity.this.getSystemService(NOTIFICATION_SERVICE);
but_down.setOnClickListener(this);
}
@Override
public void onClick(View v)
{
if (R.id.but_down == v.getId())
{
new DownloadImageTask().execute(PATH);
}
}
private class DownloadImageTask extends AsyncTask<String, Integer, Bitmap>
{
@Override
protected void onPostExecute(Bitmap result)
{
if (result != null)
{
tv_progress.setVisibility(View.GONE);
pb.setVisibility(View.GONE);
iv_show.setImageBitmap(result);
builder.setProgress(0,0,true);
builder.setContentText("下载完成");
Notification no = builder.build();
no.flags = Notification.FLAG_AUTO_CANCEL;
no.defaults = Notification.DEFAULT_SOUND;
manager.notify(1, no);
} else
{
builder.setProgress(0, 0, true);
builder.setContentText("下载失败..");
manager.notify(1,builder.build());
tv_progress.setVisibility(View.GONE);
pb.setVisibility(View.GONE);
Toast.makeText(MainActivity.this,"下载失败",0).show();
}
}
@Override
protected Bitmap doInBackground(String... params)
{
String path = params[0];
HttpClient client = new DefaultHttpClient();
HttpGet get = new HttpGet(path);
try
{
HttpResponse resp = client.execute(get);
if(resp.getStatusLine().getStatusCode() == 200)
{
HttpEntity entity = resp.getEntity();
if(entity == null)
{
return null;
}
long total_length = entity.getContentLength();//获取文件总长
InputStream is = entity.getContent();
ByteArrayOutputStream bous = new ByteArrayOutputStream();
int len = 0;
byte[] buf = new byte[1024];
int current_len = 0;
int progress = 0;//当前下载进度
while((len = is.read(buf))!= -1)
{
current_len+=len;
bous.write(buf, 0, len);
progress = (int) ((current_len/(float)total_length)*100);
this.publishProgress(progress);
}
is.close();
byte[] data = bous.toByteArray();
Options opts = new Options();
opts.inSampleSize = 2;//简单起见直接指定缩放比例
Bitmap bitmap = BitmapFactory.decodeByteArray(data, 0, data.length, opts);
return bitmap;
}
} catch (Exception e)
{
e.printStackTrace();
}
return null;
}
@Override
protected void onProgressUpdate(Integer... values)
{
tv_progress.setText("下载进度:"+values[0]);
builder.setContentText("下载进度："+values[0]+"%");
builder.setProgress(100, values[0], false);
Notification no = builder.build();
no.flags = Notification.FLAG_NO_CLEAR;
manager.notify(1,no);
no = null;
}
@Override
protected void onPreExecute()
{
tv_progress.setVisibility(View.VISIBLE);
pb.setVisibility(View.VISIBLE);
builder = new NotificationCompat.Builder(MainActivity.this);
builder.setSmallIcon(R.drawable.down);
builder.setLargeIcon(BitmapFactory.decodeResource(getResources(),R.drawable.down));
builder.setContentTitle("美女图片");
PendingIntent pi = PendingIntent.getActivity(MainActivity.this, 0, new Intent(MainActivity.this,MainActivity.class),PendingIntent.FLAG_UPDATE_CURRENT);
builder.setContentIntent(pi);
builder.setProgress(100, 0, false);
manager.notify(1,builder.build());
}
}
}
这里使用的是v4包的NotificationCompat.Builder类来产生Notification实例，如果你直接new一个Notification，那应该自定义一个Notification样式，即在通知中加一个ProgressBar。
像这样：
Notification no = new Notification(icon, tickerText, when); no.contentView.setProgressBar(viewId, max, progress, indeterminate)；