从 IntentService 或 AsyncTask 调用 REST API？

Question

想象一个典型的场景，一个活动打开，需要调用一个 REST HTTP API 来获取一些内容，并且一旦收到更新 UI。显然 API 调用需要在单独的线程上进行，但应该使用 AsyncTask、IntentService 还是其他方法来完成，为什么？

Answer 1

我会推荐IntentService 和ResultReceiver 的组合，如this post 中所述。

还可以查看实现此模型的Google iosched。 2010 版展示了如何使用 onRetainNonConfigurationInstance、getLastNonConfigurationInstance 和静态类来持久化 ResultReceiver 的配置更改（即屏幕旋转）。

我已经在一个应用程序中成功地实现了这个模型。如果您对所提供的链接有任何问题，请告诉我。

编辑：我忘记了“为什么”的问题；）

AsyncTask 与活动紧密绑定，它不能很好地处理配置更改。对于活动生命周期内的短期任务（onResume 和 onPause 之间），这很好。我将HttpClient 用于我的REST API 调用，连接超时和套接字超时设置为20 秒（由于移动网络不佳......）。这意味着 API 调用可以持续长达 40 秒。你肯定想在服务中处理这么长的任务，而不是AsyncTask。

Answer 2

回收站视图

  <android.support.v7.widget.RecyclerView
    android:id="@+id/recycler_view"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

第二活动

import android.app.ProgressDialog;
import android.os.AsyncTask;
import android.provider.SyncStateContract;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.DefaultItemAnimator;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.widget.HorizontalScrollView;
import android.widget.Toast;

import com.bumptech.glide.util.Util;

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

import java.util.ArrayList;

public class SecondActivity extends AppCompatActivity
{
    public RecyclerView recyclerView;
    public Utils utils;
    public Setget setget;
    public ArrayList<Setget>  arrayList;
    public StudentShowAdatpter studentShowAdatpter;
    public  static final String BASE_URL="http://api/";

    @Override
    protected void onCreate(Bundle savedInstanceState)
    {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main2);
        recyclerView= (RecyclerView) findViewById(R.id.recycler_view);

        utils=new Utils(SecondActivity.this);
        if(utils.isConnectingToInternet(SecondActivity.this))
        {
            new getStudentData().execute();
        }
        else
        {
            Toast.makeText(SecondActivity.this, "Please check internter connection.s", Toast.LENGTH_SHORT).show();
        }
    }

    private class getStudentData extends AsyncTask<String,String,String>
    {
        public ProgressDialog pd;

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pd=new ProgressDialog(SecondActivity.this);
            pd.setMessage("Loading...");
            pd.setCancelable(false);
            pd.show();
        }

        @Override
        protected String doInBackground(String... params)
        {
            String str_response=utils.getResponseofGet(BASE_URL+"get.php?id=7");
            return str_response;
        }

        @Override
        protected void onPostExecute(String s)
        {
            super.onPostExecute(s);
            pd.dismiss();
            try {
                JSONObject jsonObject=new JSONObject(s);
                if(jsonObject.getString("status").equalsIgnoreCase("true"))
                {
                    JSONArray jsonArray=jsonObject.getJSONArray("detail");
                        for (int i=0;i<jsonArray.length();i++)
                        {
                            JSONObject object=jsonArray.getJSONObject(i);
                            setget=new Setget();
                            setget.setStud_name(object.getString(""));
                            setget.setStud_date(object.getString(""));
                            arrayList.add(setget);
                        }
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }

            if(arrayList!=null)
            {
                studentShowAdatpter = new StudentShowAdatpter(SecondActivity.this, arrayList);
                recyclerView.setLayoutManager(new LinearLayoutManager(SecondActivity.this));
                //recyclerView.addItemDecoration(new GridSpacingItemDecoration(2, dpToPx(10), true));
                recyclerView.setItemAnimator(new DefaultItemAnimator());
                recyclerView.setAdapter(studentShowAdatpter);
            }
            else
            {
                Toast.makeText(SecondActivity.this, "Data Not Found", Toast.LENGTH_SHORT).show();
            }
        }
    }

}

适配器

import android.content.Context;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.ArrayList;


public class StudentShowAdatpter extends RecyclerView.Adapter<StudentShowAdatpter.MyViewHolder>
{
public Setget setget;
public ArrayList<Setget> arrayList;
Context context;
public StudentShowAdatpter(SecondActivity secondActivity, ArrayList<Setget> arrayList) {
    this.arrayList=arrayList;
    this.context=secondActivity;
}

@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType)
{
    View itemView = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.adapter_stud_list, parent, false);
    return new MyViewHolder(itemView);
}

@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
        setget=arrayList.get(position);
        holder.stud_name.setText(setget.getStud_name());
        holder.stud_date.setText(setget.getStud_date());
}

   @Override
public int getItemCount() {
    return arrayList.size();
}

public class MyViewHolder extends RecyclerView.ViewHolder {
    public TextView stud_name, stud_date;

    public MyViewHolder(View view) {
        super(view);
        stud_date = (TextView) view.findViewById(R.id.stud_date);
        stud_name = (TextView) view.findViewById(R.id.stud_name);
    }
}
}

Answer 3

使用 AsyncTask 调用 API 并在 RECYCLERVIEW 中显示登录和数据

build.gradle(Module.app)

dependencies {
     compile 'com.android.support:recyclerview-v7:23.3.+'
     compile 'com.android.support:cardview-v7:23.3.+'
     compile 'com.github.bumptech.glide:glide:3.7.0'
}

AndroidManifest.xml

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.INTERNET"/>

login.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_marginLeft="20dp"
    android:layout_marginTop="15dp"
    android:layout_marginRight="10dp"
    android:orientation="vertical">

    <EditText
        android:id="@+id/edit_email"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Email" />

    <EditText
        android:id="@+id/edit_password"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:hint="Enter Password" />

    <Button
        android:id="@+id/btn_login"
        android:layout_width="match_parent"
        android:layout_height="40dp"
        android:text="Login" />

</LinearLayout>

MainActivity.java

import android.app.ProgressDialog;
import android.content.Intent;
import android.os.AsyncTask;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.Toast;

import org.json.JSONException;
import org.json.JSONObject;

import java.util.HashMap;

public class MainActivity extends AppCompatActivity
{
public EditText edit_email,edit_password;
public Button btn_login;
public String str_email,str_password;
public Utils utils;
public String emailPattern = "[a-zA-Z0-9._-]+@[a-z]+.[a-z]+";
public  static final String BASE_URL="ffyy/";
@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    utils=new Utils(MainActivity.this);
    edit_email= (EditText) findViewById(R.id.edit_email);
    edit_password= (EditText) findViewById(R.id.edit_password);
    btn_login= (Button) findViewById(R.id.btn_login);

    btn_login.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v)
        {
            if (edit_email.getText().toString().trim().length() == 0)
            {
                edit_email.setError("Enter Email Id");
                return;
            }
            else if (edit_password.getText().toString().trim().length() == 0) {
                edit_password.setError("Enter Password");
                return;
            }
            else {
                str_email = edit_email.getText().toString();
                str_password = edit_password.getText().toString();
                if (utils.isConnectingToInternet(MainActivity.this)) {
                    new getLoginData().execute();
                } else {
                    Toast.makeText(MainActivity.this, "Please check internet connection.", Toast.LENGTH_SHORT).show();
                    }
            }
        }
    });
}

private class getLoginData extends AsyncTask<String,String,String>
{
    public ProgressDialog pd;

    @Override
    protected void onPreExecute()
    {
        super.onPreExecute();
        pd=new ProgressDialog(MainActivity.this);
        pd.setMessage("Loading...");
        pd.setCancelable(false);
        pd.show();
    }

    @Override
    protected String doInBackground(String... params)
    {
        HashMap<String,String> hashMap=new HashMap<>();
        hashMap.put("email", str_email);
        hashMap.put("password", str_password);
        String str_response= utils.getResponseofPost(BASE_URL+"login_for_all.php",hashMap);
        return str_response;
    }

    @Override
    protected void onPostExecute(String s)
    {
        super.onPostExecute(s);
        pd.dismiss();
        try {
            JSONObject jsonObject=new JSONObject(s);
            if(jsonObject.getString("status").equalsIgnoreCase("true"))
            {
                Toast.makeText(MainActivity.this, jsonObject.getString("msg"), Toast.LENGTH_SHORT).show();

            }
            else
            {
                Toast.makeText(MainActivity.this, jsonObject.getString("msg"), Toast.LENGTH_SHORT).show();
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }
    }
}
}

Utils.java

   import android.content.Context;
import android.content.SharedPreferences;
import android.content.pm.PackageManager;
import android.graphics.Bitmap;
import android.location.Location;
import android.net.ConnectivityManager;
import android.net.Network;
import android.net.NetworkInfo;
import android.os.Build;
import android.os.StrictMode;
import android.preference.PreferenceManager;
import android.util.Base64;
import android.util.Log;


import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.ByteArrayOutputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.Type;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLEncoder;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.HashMap;
import java.util.Map;

import javax.net.ssl.HttpsURLConnection;


public class Utils {
    static Context context;
    SharedPreferences sp;
    Location getLocation;

    public Utils(Context context) {
        this.context = context;
        //sp = context.getSharedPreferences(Constant.Prefrence, Context.MODE_PRIVATE);
    }

   /* public String getReadSharedPrefrenceIsFirstTime(Context activity, String userid) {
        String defValue = "";
        String resposne = sp.getString(Constant.ISFIRSTTIME, defValue);
        return resposne;
    }
*/
/*
    public static String convertToGson(Object object) {
        Gson gson = new Gson();
        String loginResult = gson.toJson(object);
        return loginResult;
    }

    public static <T> T GsonToObject(String strObj, Type classObject) {
        Gson gson = new Gson();
        return gson.fromJson(strObj, classObject);
    }
*/


    public void clearSharedPreferenceData() {
        sp.edit().clear().commit();
    }

    public String getResponseofPost(String URL, HashMap<String, String> postDataParams) {
        URL url;
        String response = "";
        try {
            url = new URL(URL);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setReadTimeout(15000);
            conn.setConnectTimeout(15000);
            conn.setRequestMethod("POST");
            conn.setDoInput(true);
            conn.setDoOutput(true);
            OutputStream os = conn.getOutputStream();
            BufferedWriter writer = new BufferedWriter(
                    new OutputStreamWriter(os, "UTF-8"));

            writer.write(getPostDataString(postDataParams));
            writer.flush();
            writer.close();
            os.close();
            int responseCode = conn.getResponseCode();
            if (responseCode == HttpsURLConnection.HTTP_OK) {
                String line;
                BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                while ((line = br.readLine()) != null) {
                    response += line;
                }
            } else {
                response = "";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return response;
    }

    public static String getResponseofGet(String URL) {
        URL url;
        String response = "";
        try {

            StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
            StrictMode.setThreadPolicy(policy);
            url = new URL(URL);
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setReadTimeout(15000);
            conn.setConnectTimeout(15000);
            conn.setRequestMethod("GET");
            conn.setDoInput(true);
            conn.setDoOutput(true);

            OutputStream os = conn.getOutputStream();
            BufferedWriter writer = new BufferedWriter(
                    new OutputStreamWriter(os, "UTF-8"));

            writer.flush();
            writer.close();
            os.close();
            int responseCode = conn.getResponseCode();
            Log.d("URL - ResponseCode", URL + " - " + responseCode);
            if (responseCode == HttpsURLConnection.HTTP_OK) {
                String line;
                BufferedReader br = new BufferedReader(new InputStreamReader(conn.getInputStream()));
                while ((line = br.readLine()) != null) {
                    response += line;
                }
            } else {
                response = "";
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return response;
    }

    private String getPostDataString(HashMap<String, String> params) throws
            UnsupportedEncodingException {
        StringBuilder result = new StringBuilder();
        boolean first = true;
        for (Map.Entry<String, String> entry : params.entrySet()) {
            if (first)
                first = false;
            else
                result.append("&");

            result.append(URLEncoder.encode(entry.getKey(), "UTF-8"));
            result.append("=");
            result.append(URLEncoder.encode(entry.getValue(), "UTF-8"));
        }
        return result.toString();
    }

    public String MakeServiceCall(String URLSTR) {
        StringBuilder response = null;
        try {
            response = new StringBuilder();
            URL url = new URL(URLSTR);
            HttpURLConnection httpconn = (HttpURLConnection) url.openConnection();
            if (httpconn.getResponseCode() == HttpURLConnection.HTTP_OK) {
                BufferedReader input = new BufferedReader(new InputStreamReader(httpconn.getInputStream()), 8192);
                String strLine = null;
                while ((strLine = input.readLine()) != null) {
                    response.append(strLine);
                }
                input.close();
            }
        } catch (Exception e) {
        }
        return response.toString();
    }

    private boolean appInstalledOrNot(String packageName) {
        PackageManager pm = context.getPackageManager();
        boolean app_installed;
        try {
            pm.getPackageInfo(packageName, PackageManager.GET_ACTIVITIES);
            app_installed = true;
        } catch (PackageManager.NameNotFoundException e) {
            app_installed = false;
        }
        return app_installed;
    }

    public static boolean isConnectingToInternet(Context context)
    {
        ConnectivityManager connectivityManager = (ConnectivityManager) context
                .getSystemService(Context.CONNECTIVITY_SERVICE);
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP) {
            Network[] networks = connectivityManager.getAllNetworks();
            NetworkInfo networkInfo;
            for (Network mNetwork : networks)
            {
                networkInfo = connectivityManager.getNetworkInfo(mNetwork);
                if (networkInfo.getState().equals(NetworkInfo.State.CONNECTED)) {
                    return true;
                }
            }
        } else {
            if (connectivityManager != null)
            {
                NetworkInfo[] info = connectivityManager.getAllNetworkInfo();
                if (info != null) {
                    for (NetworkInfo anInfo : info) {
                        if (anInfo.getState() == NetworkInfo.State.CONNECTED) {
                            return true;
                        }
                    }
                }
            }
        }
        return false;
    }

    public static void WriteSharePrefrence(Context context, String key, String value)
    {
        final SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
        final SharedPreferences.Editor editor = preferences.edit();
        editor.putString(key, value);
        editor.commit();
    }

    public static String ReadSharePrefrence(Context context, String key)
    {
        String data;
        final SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
        final SharedPreferences.Editor editor = preferences.edit();
        data = preferences.getString(key, "");
        editor.commit();
        return data;
    }




    public static void Clear(Context context, String key)
    {
        String data;
        final SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
        final SharedPreferences.Editor editor = preferences.edit().clear();
        editor.commit();
    }

    public static void ClearaSharePrefrence(Context context) {
        String data;
        final SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
        final SharedPreferences.Editor editor = preferences.edit().clear();
        editor.commit();
    }

    public static String encodeToBase64(Bitmap image, Bitmap.CompressFormat compressFormat, int quality) {
        ByteArrayOutputStream byteArrayOS = new ByteArrayOutputStream();
        image.compress(compressFormat, quality, byteArrayOS);
        return Base64.encodeToString(byteArrayOS.toByteArray(), Base64.DEFAULT);
    }

    public static String getLeaveStatus(String status) {
        String result = "";
        switch (status) {
            case "0":
                result = "Pending";
                break;
            case "1":
                result = "Aproved";
                break;
            case "2":
                result = "Cancel";
                break;
        }
        return result;
    }


    public String parseDateToddMMyyyy(String time)
    {
        String inputPattern = "yyyy-MM-dd HH:mm:ss";
        String outputPattern = "yyyy-MM-dd";
        SimpleDateFormat inputFormat = new SimpleDateFormat(inputPattern);
        SimpleDateFormat outputFormat = new SimpleDateFormat(outputPattern);
        Date date = null;
        String str = null;
        try {
            date = inputFormat.parse(time);
            str = outputFormat.format(date);
        } catch (ParseException e) {
            e.printStackTrace();
        }
        return str;
    }
}