Android AsyncTask 详解

/*

* 此方法在后台线程执行，完成任务的主要工作，通常需要较长的时间。

* 在执行过程中可以调用publicProgress(Progress…)来更新任务的进度。

*/

Log.i("czb", "doInBackground is running...");

try {

Bitmap bitmap;

HttpClient client = new DefaultHttpClient();

// params[0]代表连接的url

URI uri = URI.create((String) params[0]);

HttpGet get = new HttpGet(uri);

HttpResponse response = client.execute(get);

HttpEntity entity = response.getEntity();

long length = entity.getContentLength();

Log.i("czb", " " + length);

InputStream in = entity.getContent();

if (in != null) {

ByteArrayOutputStream baos = new ByteArrayOutputStream();

/*byte[] buf = new byte[128];

int ch = -1;

int count = 0;

while ((ch = in.read(buf)) != -1) {

baos.write(buf, 0, ch);

count += ch;

if (length > 0) {

// 如果知道响应的长度，调用publishProgress()更新进度

// onProgressUpdate读取进度

publishProgress((int) ((count / (float) length) * 100));

}

// 为了在模拟器中清楚地看到进度，让线程休眠100ms

//Thread.sleep(100);

}*/

bitmap = BitmapFactory.decodeStream(in);

in.close();

baos.close();

return bitmap;

}

} catch (Exception e) {

e.printStackTrace();

}

return null;

}

}

}