Android开发之自带下载器DownloadManager的使用示例代码

public class DownloadUtils {
  //下载器
  private DownloadManager downloadManager;
  //上下文
  private Context mContext;
  //下载的ID
  private long downloadId;
  public DownloadUtils(Context context){
    this.mContext = context;
  }

  //下载apk
  public void downloadAPK(String url, String name) {

    //创建下载任务
    Request request = new Request(Uri.parse(url));
    //移动网络情况下是否允许漫游
    request.setAllowedOverRoaming(false);

    //在通知栏中显示，默认就是显示的
    request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE);
    request.setTitle("新版本Apk");
    request.setDescription("Apk Downloading");
    request.setVisibleInDownloadsUi(true);

    //设置下载的路径
    request.setDestinationInExternalPublicDir(Environment.getExternalStorageDirectory().getAbsolutePath() , name);

    //获取DownloadManager
    downloadManager = (DownloadManager) mContext.getSystemService(Context.DOWNLOAD_SERVICE);
    //将下载请求加入下载队列，加入下载队列后会给该任务返回一个long型的id，通过该id可以取消任务，重启任务、获取下载的文件等等
    downloadId = downloadManager.enqueue(request);

    //注册广播接收者，监听下载状态
    mContext.registerReceiver(receiver,
        new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE));
  }

  //广播监听下载的各个状态
  private BroadcastReceiver receiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
      checkStatus();
    }
  };


  //检查下载状态
  private void checkStatus() {
    Query query = new Query();
    //通过下载的id查找
    query.setFilterById(downloadId);
    Cursor c = downloadManager.query(query);
    if (c.moveToFirst()) {
      int status = c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS));
      switch (status) {
         //下载暂停
        case DownloadManager.STATUS_PAUSED:
          break;
        //下载延迟
        case DownloadManager.STATUS_PENDING:
          break;
        //正在下载
        case DownloadManager.STATUS_RUNNING:
          break;
        //下载完成
        case DownloadManager.STATUS_SUCCESSFUL:
          //下载完成安装APK
          installAPK();
          break;
        //下载失败
        case DownloadManager.STATUS_FAILED:
          Toast.makeText(mContext, "下载失败", Toast.LENGTH_SHORT).show();
          break;
      }
    }
  }

  //下载到本地后执行安装
  private void installAPK() {
    //获取下载文件的Uri
    Uri downloadFileUri = downloadManager.getUriForDownloadedFile(downloadId);
    if (downloadFileUri != null) {
      Intent intent= new Intent(Intent.ACTION_VIEW);
      intent.setDataAndType(downloadFileUri, "application/vnd.android.package-archive");
      intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
      mContext.startActivity(intent);
    }
  }

}

public class MainActivity extends AppCompatActivity {
  private DownloadUtils downloadUtils;
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    downloadUtils =  new DownloadUtils(MainActivity.this); 
    downloadUtils.downloadAPK("http://192.168.1.104:8080/XXX.apk", "XXX.apk");

  }
}

<!--在SDCard中创建与删除文件权限 -->
<uses-permission android:name="android.permission.MOUNT_UNMOUNT_FILESYSTEMS"/>
<!-- 往SDCard写入数据权限 -->
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<!-- 从SDCard读取数据权限 -->
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<!-- 访问网络权限 -->
<uses-permission android:name="android.permission.INTERNET"/>