在android2.3以后android系统提供了一个系统组件来供其他app调用来下载东西，使用起来非常方便。

例如我们可以拿来下载app的新版本apk，同时在同时注册一个广播接收器来接收下载完成时DownloadManager发出的的广播，然后自动安装程序。

SDK在API Level 9中加入了DownloadManager服务，可以将长时间的下载任务交给系统，完全由系统管理。

直接看实例代码：

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;

}

}

}

}

最后需要的权限是：

如果需要隐藏下载工具的提示和显示，修改代码：

request.setShowRunningNotification(false);

request.setVisibleInDownloadsUi(false);

加入下面的权限：

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。