java - 从 AsyncTask 返回一个值到主类

Question

我是 android 的新手，我开发了一个应用程序来发布并从 php 服务器获取响应。

异步任务

    class MyTask extends AsyncTask<String, Void, String> {


    @Override
    protected String doInBackground(String... arg0) {


        // Create a new HttpClient and Post Header
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("http://172.16.110.3/agent_tracking/index.php/api/rest/auth");

        try {
            // Add your data
            List<BasicNameValuePair> nameValuePairs = new ArrayList<>(1);
            nameValuePairs.add(new BasicNameValuePair("key", arg0[0]));
           // nameValuePairs.add(new BasicNameValuePair("stringdata", "Hi"));
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

            // Execute HTTP Post Request
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();
            String responseString = EntityUtils.toString(entity, "UTF-8");

            return responseString;

        } catch (ClientProtocolException e) {
            // TODO Auto-generated catch block
        } catch (IOException e) {
            // TODO Auto-generated catch block
        }
        return null;
    }
}

主类

  Button login = (Button) findViewById(R.id.btn_login);
    login.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View v) {
            EditText username = (EditText) findViewById(R.id.et_user_name);
            EditText password = (EditText) findViewById(R.id.et_password);

            String user_name = username.getText().toString();
            String paswrd = password.getText().toString();
            String timeStamp = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(Calendar.getInstance().getTime());

            String data2 = user_name + "|" + paswrd + "|" + timeStamp;

            byte[] data = new byte[0];
            try {
                data = data2.getBytes("UTF-8");
            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
            String base64 = Base64.encodeToString(data, Base64.DEFAULT);

            show_message(base64);
            new MyTask().execute(base64);
            //postData();
            //startActivity(new Intent(MainActivity.this, mainmenu.class));
        }
    });

我的问题是从 AsyncTask 返回一个名为 responseString 的值。我想从主类中捕获该值并将其显示在消息框中。

我试过这样

     String result = new MyTask().execute(base64);

我收到错误无法比较的类型错误。

谁能帮我把返回的值传给主类

Answer 1

有多种方法可以实现这一点。我正在逐步描述一种方法:

1) 在您的 Activity 中创建一个方法，它将对 Activity 等执行所需的操作。

public void showData(String responseString)
{
    tvText.setText(responseString)
}

2) 当您在 asyncTask 中调用您的 asyncTask 传递 Activity 对象时，例如

new MyTask(MainClass.this).execute(base64);

3) 从 onPostExecute 调用 showData 方法，例如:

mainclassObj.showData(response);