使用Android系统提供的DownloadManager来下载文件

package com.hebaijun.downloadtest; 
 
import java.io.UnsupportedEncodingException; 
import java.net.URLEncoder; 
 
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.content.SharedPreferences; 
import android.database.Cursor; 
import android.net.Uri; 
import android.os.Bundle; 
import android.preference.PreferenceManager; 
import android.util.Log; 
import android.webkit.MimeTypeMap; 
 
public class DownloadTestActivity extends Activity { 
  private DownloadManager downloadManager; 
  private SharedPreferences prefs; 
  private static final String DL_ID = "downloadId"; 
  /** Called when the activity is first created. */ 
  @Override 
  public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(R.layout.main); 
    downloadManager = (DownloadManager)getSystemService(DOWNLOAD_SERVICE); 
    prefs = PreferenceManager.getDefaultSharedPreferences(this);  
  } 
  @Override 
  protected void onPause() { 
    // TODO Auto-generated method stub 
    super.onPause(); 
    unregisterReceiver(receiver); 
  } 
  @Override 
  protected void onResume() { 
    // TODO Auto-generated method stub 
    super.onResume(); 
    if(!prefs.contains(DL_ID)) {  
      String url = "http://10.0.2.2/android/film/G3.mp4"; 
      //开始下载  
      Uri resource = Uri.parse(encodeGB(url));  
      DownloadManager.Request request = new DownloadManager.Request(resource);  
      request.setAllowedNetworkTypes(Request.NETWORK_MOBILE | Request.NETWORK_WIFI);  
      request.setAllowedOverRoaming(false);  
      //设置文件类型 
      MimeTypeMap mimeTypeMap = MimeTypeMap.getSingleton(); 
      String mimeString = mimeTypeMap.getMimeTypeFromExtension(MimeTypeMap.getFileExtensionFromUrl(url)); 
      request.setMimeType(mimeString); 
      //在通知栏中显示  
      request.setShowRunningNotification(true); 
      request.setVisibleInDownloadsUi(true); 
      //sdcard的目录下的download文件夹 
      request.setDestinationInExternalPublicDir("/download/", "G3.mp4"); 
      request.setTitle("移动G3广告");  
      long id = downloadManager.enqueue(request);  
      //保存id  
      prefs.edit().putLong(DL_ID, id).commit();  
    } else {  
      //下载已经开始，检查状态 
      queryDownloadStatus();  
    }  
 
    registerReceiver(receiver, new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE)); 
  } 
   
  /** 
   * 如果服务器不支持中文路径的情况下需要转换url的编码。 
   * @param string 
   * @return 
   */ 
  public String encodeGB(String string) 
  { 
    //转换中文编码 
    String split[] = string.split("/"); 
    for (int i = 1; i 

request.setShowRunningNotification(false);
request.setVisibleInDownloadsUi(false);