大家肯定都会经常使用AsyncTask这个类，特别是在网络处理中，先看改正后的代码：这是正常的代码：
class sendKeyTask extends AsyncTask<String, Void, Integer>
{
@Override
protected void onPostExecute(Integer resultCode) {
// TODO Auto-generated method stub
super.onPostExecute(resultCode);
switch (resultCode) {
case 6000:
NotifyHelper.popNotifyInfo(InnerQuestionActivity.this, "用户信息异常", "");
break;
case 6001:
NotifyHelper.popNotifyInfo(InnerQuestionActivity.this, "其他异常", "");
break;
case 6002:
break;
default:
break;
}
// 隐藏输入法
InputMethodManager imm = (InputMethodManager) getApplicationContext().getSystemService(Context.INPUT_METHOD_SERVICE);
// 显示或者隐藏输入法
imm.toggleSoftInput(0, InputMethodManager.HIDE_NOT_ALWAYS);
innerQuestionEdit.setText("");
//从新刷新
new getQuestionDetailTack().execute(1);
}
@Override
protected Integer doInBackground(String... data) {
// TODO Auto-generated method stub
int resultCode=4001;
HttpClient client= new DefaultHttpClient();
HttpPost post = new HttpPost("http://diandianapp.sinaapp.com/add_key.php");
StringBuilder builder = new StringBuilder();
List<NameValuePair> paramsList=new ArrayList<NameValuePair>();
paramsList.add(new BasicNameValuePair("access_token", data[0]));
paramsList.add(new BasicNameValuePair("user_name", data[1]));
paramsList.add(new BasicNameValuePair("key_detail", data[2]));
paramsList.add(new BasicNameValuePair("question_id", data[3]));
for(int i=0;i<jpegDataList.size();i++)
{
paramsList.add(new BasicNameValuePair
("img"+String.valueOf(i), jpegDataList.get(i)));
}
try {
post.setEntity( new UrlEncodedFormEntity(paramsList,HTTP.UTF_8));
} catch (UnsupportedEncodingException e1) {
e1.printStackTrace();
}
try {
HttpResponse response = client.execute(post);
HttpEntity entity = response.getEntity();
BufferedReader reader = new BufferedReader(new InputStreamReader(entity.getContent()));
for (String s = reader.readLine(); s != null; s = reader.readLine()) {
builder.append(s);
}
JSONObject jsonObject = new JSONObject(builder.toString());
String stateCodeStr = jsonObject.getString("state_code");
resultCode=Integer.parseInt(stateCodeStr);
}
catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
//处理请求失败
}
finally
{
}
return resultCode;
}
}
可能有人会说，我让doInBackground返回一个参数，再在onPostExecute里面处理不是多次一举吗？但是，当你真的将两部分合成后，会发现，竟然报错了！报错内容大体为UI内容只能在主线程更改；这是为什么呢！
NotifyHelper.popNotifyInfo(InnerQuestionActivity.this, "其他异常", "");是对对话提示框的一个弹出方法封装，这是对UI界面的操作，问题应该就出在这儿了！
我们翻开google的说明看下：
protected abstract Result
doInBackground (Params... params)
Added in API level 3
Override this method to perform a computation on a background thread. The specified parameters are the parameters passed to
execute(Params...) by the caller of this task. This method can call
publishProgress(Progress...) to publish updates on the UI thread.
Parameters
| params | The parameters of the task. |
|---|
Returns
- A result, defined by the subclass of this task.
protected void onPostExecute
(Result result)
Added in API level 3
Runs on the UI thread after doInBackground(Params...). The specified result is the value returned by
doInBackground(Params...).
This method won‘t be invoked if the task was cancelled.
Parameters
| result | The result of the operation computed by doInBackground(Params...). |
|---|
See Also
protected void onPreExecute
()
Added in API level 3
Runs on the UI thread before doInBackground(Params...).
我们可以看出，这几个重载方法只有doInBackground是在后台线程运行的，而后台是不能执行更新线程的操作的！
我们必须要在doInbackground中，返回耗时操作的处理结果，再从onPostExecute中根据doInBackground返回的参数进行UI组件的操作！
doInBackground