android调用系统下载器下载文件

   在项目中使用到了在android端下载服务端的文件，之前使用的是http下载方式，现在想改成调用系统的下载器进行下载，实现步骤为：

  1.得到url：文件下载地址

  2.使用URL下载：

 (1)下载前先判断文件是否已经在下载，避免重复下载：

  

// 判断该文件是否在下载private boolean isDowning(String uri) {boolean flag = false;try {DownloadManager.Query query = new DownloadManager.Query();query.setFilterByStatus(DownloadManager.STATUS_RUNNING);if (downloadManager == null) {downloadManager = ((DownloadManager) this.getSystemService(Activity.DOWNLOAD_SERVICE));}Cursor c = downloadManager.query(query);String downingURI;while (c.moveToNext()) {downingURI = c.getString(c.getColumnIndex(DownloadManager.COLUMN_URI));if (downingURI.equalsIgnoreCase(uri)) {flag = true;break;}}if (c != null) {c.close();}} catch (Exception ex) {ex.printStackTrace();}return flag;}

  （2）如果未在下载则下载文件：

// 本地存储路径Request request = new Request(Uri.parse(url));// 在通知栏中显示request.setShowRunningNotification(true);request.setVisibleInDownloadsUi(true);String dir ="tempFilrDir";//本地文件存储目录 相对路径String fileName =  "悟空.mp3";//下载的文件名称

request.setDestinationInExternalPublicDir(dir, fileName);//文件存储路径 绝对路径request.setTitle(<span style="font-family: KaiTi_GB2312;">fileName </span>);//下载时在通知栏显示的文字

//downloadManager = ((DownloadManager) this.getSystemService(Activity.DOWNLOAD_SERVICE));

<pre name="code" class="java">long downloadId = downloadManager.enqueue(request);//执行下载   

DownloadCompleteReceiver.mDownloadIDs.add(new Long(downloadId));//DownloadCompleteReceiver下载完成的接收器，第//3步会讲到

(3)接收完成的接收器

<span style="font-family: KaiTi_GB2312;"></span><pre name="code" class="java">package com.bcts.appmanage.manage;import java.util.ArrayList;import android.app.DownloadManager;import android.content.BroadcastReceiver;import android.content.Context;import android.content.Intent;import android.database.Cursor;import android.os.Handler;import android.os.Message;import android.util.Log;import com.bcts.appmanage.tools.Constant;/** * 调用系统下载器下载文件 *   */public class DownloadCompleteReceiver extends BroadcastReceiver {public static final String TAG = "DownloadCompleteReceiver";public static ArrayList<Long> mDownloadIDs = new ArrayList<Long>();public String fileName;public  Handler mHandler;public  DownloadCompleteReceiver(Handler handler) {mHandler = handler ;}@Overridepublic void onReceive(Context context, Intent intent) {if (intent.getAction().equals(DownloadManager.ACTION_DOWNLOAD_COMPLETE)) {long downId = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);//if (mDownloadIDs.contains(downId)) {// //////////////////////////////DownloadManager downloadManager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);DownloadManager.Query query = new DownloadManager.Query();// query.setFilterByStatus(DownloadManager.STATUS_SUCCESSFUL);query.setFilterById(downId);Cursor c = downloadManager.query(query);if (c.moveToFirst()) {fileName = c.getString(c.getColumnIndex(DownloadManager.COLUMN_LOCAL_FILENAME));Message m = new Message();m.obj = fileName;m.what = Constant.DOWNLOAD_FINISHED;mHandler.sendMessage(m);Log.i(TAG, "下载'" + fileName + "'完成");}else{Log.i(TAG, "下载'" + fileName + "'失败");}if (c != null) {c.close();}mDownloadIDs.remove(downId);}}}}

(4)注册接收完成的广播

<span style="font-family: KaiTi_GB2312;">   </span><pre name="code" class="java">downloadCompleteReceiver = new DownloadCompleteReceiver(mHandler);IntentFilter myIntentFilter = new IntentFilter();myIntentFilter.addAction(DownloadManager.ACTION_DOWNLOAD_COMPLETE);// 注册广播registerReceiver(downloadCompleteReceiver, myIntentFilter);