Android下载文件（1）

• service下载文件，加入标签：

<service android:name=".MyService"></service>

添加相关权限：

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

• 代码如下：

  public class MainActivity extends Activity {
      private Button button;

  @Override
      protected void onCreate(Bundle savedInstanceState) {
          // TODO Auto-generated method stub
          super.onCreate(savedInstanceState);
          setContentView(R.layout.mainactivity);
          button = (Button) findViewById(R.id.button1);
          button.setOnClickListener(new OnClickListener() {

  @Override
              public void onClick(View arg0) {
                  // TODO Auto-generated method stub
                  Intent intent = new Intent(MainActivity.this,MyService.class);
                  startService(intent);
              }
          });
      }
  }

  public class MyService extends Service {
      private final String DOWNPATH = "http://www.baidu.com/img/bdlogo.png";//下载链接

  @Override
      public void onCreate() {
          // TODO Auto-generated method stub
          super.onCreate();
      }

  @Override
      public int onStartCommand(Intent intent, int flags, int startId) {
          // TODO Auto-generated method stub
          // 不能直接使用Http协议使用网络，service在UI线程当中，需要创建线程，与主线程分离
          final Handler handler = new Handler() {
              @Override
              public void handleMessage(Message msg) {
                  // TODO Auto-generated method stub
                  super.handleMessage(msg);
                  if (msg.what == 1) {
                      stopSelf();
                      Toast.makeText(getApplicationContext(), "文件下载完毕", 1).show();
                  }
              }
          };

  Thread thread = new Thread(new Runnable() {
              @Override
              public void run() {
                  // TODO Auto-generated method stub
                  HttpClient httpClient = new DefaultHttpClient();
                  HttpPost httpPost = new HttpPost(DOWNPATH);
                  HttpResponse httpResponse = null;
                  // 获得SD卡的目录
                  File file = Environment.getExternalStorageDirectory();
                  FileOutputStream outStream = null;
                  try {
                      httpResponse = httpClient.execute(httpPost);
                      if (httpResponse.getStatusLine().getStatusCode() == 200) {
                          byte[] result = EntityUtils.toByteArray(httpResponse
                                  .getEntity());
                          // 判断SDK卡是否挂载，并且可以存储数据
                          if (Environment.getExternalStorageState().equals(
                                  Environment.MEDIA_MOUNTED)) {
                              File new_file = new File(file, "bdlogo.png");
                              outStream = new FileOutputStream(new_file);
                              outStream.write(result, 0, result.length);
                              Message message = Message.obtain();
                              message.what = 1;
                              handler.sendMessage(message);
                              // 关闭service

  }
                      }
                  } catch (Exception e) {
                      // TODO Auto-generated catch block
                      e.printStackTrace();
                  } finally {
                      try {
                          outStream.close();
                          httpClient.getConnectionManager().shutdown();
                      } catch (IOException e) {
                          // TODO Auto-generated catch block
                          e.printStackTrace();
                      }

  }
              }
          });
          thread.start();
          return super.onStartCommand(intent, flags, startId);
      }

  @Override
      public IBinder onBind(Intent arg0) {
          // TODO Auto-generated method stub
          return null;
      }

  }