loader或AsyncTask有什么区别? [英] What is the difference between loader or AsyncTask?

问题描述

我想知道Android加载器和AsyncTask之间的区别， 这里是关于Loader的演示:

I want to know the difference between Android loader and AsyncTask , here the demo on Loader:

package com.android.loaderdemo;

import org.json.JSONArray;
import org.json.JSONObject;

import android.app.Activity;
import android.app.LoaderManager.LoaderCallbacks;
import android.content.AsyncTaskLoader;
import android.content.Context;
import android.content.Loader;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.widget.TextView;

import com.android.webprocessor.Http_GetServices;

public class MainActivity extends Activity implements LoaderCallbacks<String> {
    TextView txt_username, txt_userEmail, txt_password, txt_role, txt_secretQuestion, txt_answer, txt_zipcode;

    private static String url = "http://dotstg1.xyz.com/loud/webservcies/GetUserProfile.svc/GetUserProfile/124";
    static String response;
    static String name, email, Pasword, Answer, RoleId, SecretQuestion, Zip;

    static String useResult = null;

    static JSONArray userParams = null;

    private static final int THE_LOADER = 0x01;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        Log.e("onCreate", "onCreate");
        // getSuLoaderManager().initLoader(THE_LOADER, null, this).forceLoad();
        getLoaderManager().initLoader(THE_LOADER, null, this).forceLoad();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        Log.e("onCreateOptionsMenu", "onCreateOptionsMenu");
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public Loader<String> onCreateLoader(int arg0, Bundle arg1) {
        Log.e("onCreateLoader", "onCreateLoader");
        SampleLoader loader = new SampleLoader(this);

        return loader;
    }

    @Override
    public void onLoadFinished(Loader<String> arg0, String arg1) {
        txt_username = (TextView) findViewById(R.id.name);
        txt_userEmail = (TextView) findViewById(R.id.email);
        txt_password = (TextView) findViewById(R.id.password);
        txt_role = (TextView) findViewById(R.id.role);
        txt_secretQuestion = (TextView) findViewById(R.id.secretquestion);
        txt_zipcode = (TextView) findViewById(R.id.zipcode);
        txt_answer = (TextView) findViewById(R.id.answer);

        txt_username.setText(name);
        txt_userEmail.setText(email);
        txt_password.setText(Pasword);
        txt_role.setText(RoleId);
        txt_secretQuestion.setText(SecretQuestion);
        txt_answer.setText(Answer);
        txt_zipcode.setText(Zip);
        Log.e("onLoadFinished", "onLoadFinished");
    }

    @Override
    public void onLoaderReset(Loader<String> arg0) {
        Log.e("onLoaderReset", "onLoaderReset");

    }

    private static class SampleLoader extends AsyncTaskLoader<String> {

        @Override
        public Context getContext() {
            Log.e("getContext", "getContext");
            return super.getContext();
        }

        @Override
        public int getId() {
            Log.e("getId", "getId");
            return super.getId();
        }

        public SampleLoader(Context context) {

            super(context);
            Log.e("SampleLoader", "SampleLoader");
        }

        @Override
        public String loadInBackground() {
            Log.e("loadInBackground", "loadInBackground");
            try {
                response = Http_GetServices.connect(url);
                JSONObject jsonObject = new JSONObject(response);
                JSONObject json2 = jsonObject.getJSONObject("GetUserPrfResult");
                String test = (String) json2.get("Descritption");
                JSONObject json3 = json2.getJSONObject("GetUserPrfParams");

                name = (String) json3.get("Name");
                email = (String) json3.get("Email");
                Pasword = (String) json3.get("Pasword");
                RoleId = String.valueOf(json3.getInt("RoleId"));
                SecretQuestion = String.valueOf(json3.get("SecretQuestion"));
                Answer = (String) json3.get("Answer");
                Zip = String.valueOf(json3.get("Zip"));

            }
            catch (Exception e) {
                e.printStackTrace();
            }

            return null;
        }

    }

}

推荐答案

来自

Loaders的一个子类是AsyncTaskLoader.这堂课表演 与AsyncTask相同的功能，但要好一些.它可以处理 活动配置更容易更改，并且行为在 碎片和活动的生命周期.不错的是 AsyncTaskLoader可以在以下情况下使用: 正在使用.任何时候需要将数据加载到内存中 要处理的活动/片段，AsyncTaskLoader可以完成工作 更好.

One subclass of Loaders is the AsyncTaskLoader. This class performs the same function as the AsyncTask, but a bit better. It can handle Activity configuration changes more easily, and it behaves within the life cycles of Fragments and Activities. The nice thing is that the AsyncTaskLoader can be used in any situation that the AsyncTask is being used. Anytime data needs to be loaded into memory for the Activity/Fragment to handle, The AsyncTaskLoader can do the job better.

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