android – AsyncTask;调用方法onPreExecute()后调用doInbackground()

我在我的项目中添加了异步库,并且已经检查了,我不知道为什么代码流不会进入asynctask

码

public void doMysqL()
{
    Log.v("doMysqL","accessed");

    new AsyncTask<Void,Void,String>() {
        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            Log.e("AsyncTask","onPreExecute");
        }
        @Override
        protected String doInBackground(Void... params) {
            Log.v("AsyncTask","doInBackground");

            String msg = "";

            DefaultHttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://172.16.100.172:52273/MysqL");

            ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();

            nameValuePairs.add(new BasicNameValuePair("myday",Integer.toString(day_picker.getYear()) + 
                    addZero(day_picker.getMonth() + 1) + 
                    addZero(day_picker.getDayOfMonth())));
            nameValuePairs.add(new BasicNameValuePair("mystar",changeStar(day_picker.getMonth() + 1,day_picker.getDayOfMonth())));
            nameValuePairs.add(new BasicNameValuePair("mybt",changeBloodType(blood_picker.getValue())));
            nameValuePairs.add(new BasicNameValuePair("mynum","" + myPhone.getText()));
            nameValuePairs.add(new BasicNameValuePair("yournum","" + partnerPhone.getText()));
            nameValuePairs.add(new BasicNameValuePair("myregID",regid));
            try {
                Log.v("setEntity","before");
                httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
                Log.v("setEntity","after");

            } catch (UnsupportedEncodingException e1) {
                Log.v("UnsupportedEncodingException","");
                e1.printStackTrace();
            }
            //172.16.101.28
            try {  
                Log.v("post","before");
                HttpResponse httpresponse = httpclient.execute(httppost);
                Log.v("post","after");
                Log.v("HttpResponse ",httpresponse.getEntity().toString());
            } catch (ClientProtocolException e) {
                Log.v("ClientProtocolException","ClientProtocolException");
                e.printStackTrace();
            } catch (IOException e) {
                Log.v("IOException","IOException");

                e.printStackTrace();
            }

            return msg;
        }
        @Override
        protected void onPostExecute(String msg) {
            Log.v("AsyncTask","onPostExecute");

        }
    }.execute(null,null,null);
}

我在代码“Log.v(”AsyncTask“,”doInBackground“)中有一个日志语句;

但它不会出现在记录器中的Log.v(“AsyncTask”,“doInBackground”);

解决方法

你应该执行你的任务

task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);

因为在较低版本的Android中,所有AsyncTasks都在单个后台线程中执行.所以新任务可能会等待,直到其他任务工作.

在Android的较低版本(实际上在HONEYCOMB之前),您无法在执行器上执行AsyncTask.

将您的代码更改为

public void executeAsyncTask()
{
    AsyncTask<Void,String> task = new AsyncTask<Void,"onPreExecute");
        }

        @Override
        protected String doInBackground(Void... params) {
            Log.v("AsyncTask","doInBackground");
            String msg = null;
            // some calculation logic of msg variable
            return msg;
        }
        @Override
        protected void onPostExecute(String msg) {
            Log.v("AsyncTask","onPostExecute");
        }
    };

    if(Build.VERSION.SDK_INT >= 11/*HONEYCOMB*/) {
        task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR);
    } else {
        task.execute();
    }
}

android – AsyncTask;调用方法onPreExecute()后调用doInbackground()

解决方法

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