android使用dowanloadmanager下载东西，并且获取下载进度。

package com.koolsee.gallery;

import java.util.ArrayList;
import java.util.List;
import java.util.Timer;
import java.util.TimerTask;

import android.app.Activity;
import android.app.DownloadManager;
import android.app.DownloadManager.Request;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.database.ContentObserver;
import android.database.Cursor;
import android.net.Uri;
import android.os.Bundle;
import android.os.Environment;
import android.os.Handler;
import android.util.Log;
import android.view.KeyEvent;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnKeyListener;
import android.view.View.OnTouchListener;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

import com.koolsee.gallery.adapter.RecommendAdapter;
import com.koolsee.gallery.model.Recommend;
import com.koolsee.gallery.widget.GalleryFlow;

/**
* 首页
*
* @author zengxiaotao
*/
public class testActivity extends Activity {

private DownloadManager dowanloadmanager = null;
private DownloadChangeObserver downloadObserver;
private long lastDownloadId = 0;
public static final Uri CONTENT_URI = Uri.parse("content://downloads/my_downloads");
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.test);
String serviceString = Context.DOWNLOAD_SERVICE;
dowanloadmanager = (DownloadManager) getSystemService(DOWNLOAD_SERVICE);

Uri uri = Uri.parse("http://commonsware.com/misc/test.mp4");
Environment.getExternalStoragePublicDirectory(
Environment.DIRECTORY_DOWNLOADS).mkdir();

lastDownloadId = dowanloadmanager.enqueue(new DownloadManager.Request(uri)
.setAllowedNetworkTypes(
DownloadManager.Request.NETWORK_MOBILE
| DownloadManager.Request.NETWORK_WIFI)
.setAllowedOverRoaming(false)
.setDestinationInExternalPublicDir(
Environment.DIRECTORY_DOWNLOADS, "test.mp4"));
registerReceiver(receiver, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));
downloadObserver = new DownloadChangeObserver(null);
getContentResolver().registerContentObserver(CONTENT_URI, true, downloadObserver);
}
class DownloadChangeObserver extends ContentObserver {

public DownloadChangeObserver(Handler handler) {
super(handler);
// TODO Auto-generated constructor stub
}

@Override
public void onChange(boolean selfChange) {
queryDownloadStatus();
}

}
private BroadcastReceiver receiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
//这里可以取得下载的id，这样就可以知道哪个文件下载完成了。适用与多个下载任务的监听
Log.v("tag", ""+intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, 0));
queryDownloadStatus();
}
};

private void queryDownloadStatus() {
DownloadManager.Query query = new DownloadManager.Query();
query.setFilterById(lastDownloadId);
Cursor c = dowanloadmanager.query(query);
if(c!=null&&c.moveToFirst()) {
int status = c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS));

int reasonIdx = c.getColumnIndex(DownloadManager.COLUMN_REASON);
int titleIdx = c.getColumnIndex(DownloadManager.COLUMN_TITLE);
int fileSizeIdx =
c.getColumnIndex(DownloadManager.COLUMN_TOTAL_SIZE_BYTES);
int bytesDLIdx =
c.getColumnIndex(DownloadManager.COLUMN_BYTES_DOWNLOADED_SO_FAR);
String title = c.getString(titleIdx);
int fileSize = c.getInt(fileSizeIdx);
int bytesDL = c.getInt(bytesDLIdx);

// Translate the pause reason to friendly text.
int reason = c.getInt(reasonIdx);
StringBuilder sb = new StringBuilder();
sb.append(title).append("\n");
sb.append("Downloaded ").append(bytesDL).append(" / " ).append(fileSize);

// Display the status
Log.d("tag", sb.toString());
switch(status) {
case DownloadManager.STATUS_PAUSED:
Log.v("tag", "STATUS_PAUSED");
case DownloadManager.STATUS_PENDING:
Log.v("tag", "STATUS_PENDING");
case DownloadManager.STATUS_RUNNING:
//正在下载，不做任何事情
Log.v("tag", "STATUS_RUNNING");

break;
case DownloadManager.STATUS_SUCCESSFUL:
//完成
Log.v("tag", "下载完成");
//	                dowanloadmanager.remove(lastDownloadId);
break;
case DownloadManager.STATUS_FAILED:
//清除已下载的内容，重新下载
Log.v("tag", "STATUS_FAILED");
dowanloadmanager.remove(lastDownloadId);
break;
}
}
}

@Override
protected void onDestroy() {
// TODO Auto-generated method stub
super.onDestroy();
unregisterReceiver(receiver);
getContentResolver().unregisterContentObserver(downloadObserver);
}
}