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 < split.length; i++) {       try {         split[i] = URLEncoder.encode(split[i], "GB2312");       } catch (UnsupportedEncodingException e) {         e.printStackTrace();       }       split[0] = split[0]+"/"+split[i];     }     split[0] = split[0].replaceAll("//+", "%20");//处理空格     return split[0];   }      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("intent", ""+intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, 0));       queryDownloadStatus();      }    };       private void queryDownloadStatus() {      DownloadManager.Query query = new DownloadManager.Query();      query.setFilterById(prefs.getLong(DL_ID, 0));      Cursor c = downloadManager.query(query);      if(c.moveToFirst()) {        int status = c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS));        switch(status) {        case DownloadManager.STATUS_PAUSED:          Log.v("down", "STATUS_PAUSED");       case DownloadManager.STATUS_PENDING:          Log.v("down", "STATUS_PENDING");       case DownloadManager.STATUS_RUNNING:          //正在下载，不做任何事情         Log.v("down", "STATUS_RUNNING");         break;        case DownloadManager.STATUS_SUCCESSFUL:          //完成         Log.v("down", "下载完成");         break;        case DownloadManager.STATUS_FAILED:          //清除已下载的内容，重新下载         Log.v("down", "STATUS_FAILED");         downloadManager.remove(prefs.getLong(DL_ID, 0));          prefs.edit().clear().commit();          break;        }      }   } } 

<uses-permission android:name="android.permission.INTERNET"/><uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

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

<uses-permission android:name="android.permission.DOWNLOAD_WITHOUT_NOTIFICATION"/>