java - 如何将字符串值从 Activity 发送到异步任务？

Question

我有 IzborKategorija.java Activity ，根据用户的复选框选择创建 STRING，我需要将其发送到 asyncTask 作为我用来创建 GET 方法的 url 的最后一部分。因此，我创建如下字符串:3,6,7,9，我需要将此字符串附加到“http://www.example.com/push/?device_token=”+regid+“&channels_ids=”+STRINGFROMACTIVITY。我的 AsyncTask 已经在等待 GCM 注册，如何在那里再添加一个参数？

我的 Activity IzborKategorija.java:

import java.util.ArrayList;
import java.util.Arrays;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.util.Log;
import android.util.SparseBooleanArray;
import android.view.View;
import android.widget.ArrayAdapter;
import android.widget.Button;
import android.widget.ListView;
import android.widget.Toast;

public class IzborKategorija extends Activity{
    ListView myList;
    Button getChoice, clearAll;
    SharedPreferences sharedpreferences;
    public static final String MyPREFERENCES = "MyUserChoice" ;
    ArrayList<String> selectedItems = new ArrayList<String>();
    private static final String TAG = "KATARINA";
    String savedItems;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        myList = (ListView)findViewById(R.id.list);
        getChoice = (Button)findViewById(R.id.getchoice);
        clearAll = (Button)findViewById(R.id.clearall);
        ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_multiple_choice, getResources().getStringArray(R.array.Mobile_OS));
        myList.setChoiceMode(ListView.CHOICE_MODE_MULTIPLE);
        myList.setAdapter(adapter);

        sharedpreferences = getSharedPreferences(MyPREFERENCES, Context.MODE_PRIVATE);
        if(sharedpreferences.contains(MyPREFERENCES)){
            LoadSelections();
        }

        getChoice.setOnClickListener(new Button.OnClickListener(){


            @Override
            public void onClick(View v) {

                String selected = "";
                int cntChoice = myList.getCount();

                SparseBooleanArray sparseBooleanArray = myList.getCheckedItemPositions();
                for(int i = 0; i < cntChoice; i++){
                    if(sparseBooleanArray.get(i)) {
                        selected += myList.getItemAtPosition(i).toString() + "\n";
                        System.out.println("Checking list while adding:" + myList.getItemAtPosition(i).toString());
                        SaveSelections();
                    }

                }


                Toast.makeText(IzborKategorija.this, selected, Toast.LENGTH_LONG).show();

            }});

        clearAll.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
// TODO Auto-generated method stub
                ClearSelections();
            }
        });


    }

    private void SaveSelections() {
// save the selections in the shared preference in private mode for the user

        SharedPreferences.Editor prefEditor = sharedpreferences.edit();
        String savedItems = getSavedItems();
        prefEditor.putString(MyPREFERENCES.toString(), savedItems);
        prefEditor.commit();
    }

    private String getSavedItems() {
        String savedItems = "";
        int count = this.myList.getAdapter().getCount();
        for (int i = 0; i < count; i++) {
            if (this.myList.isItemChecked(i)) {
                if (savedItems.length() > 0) {
                    savedItems += "," + this.myList.getItemAtPosition(i);
                } else {
                    savedItems += this.myList.getItemAtPosition(i);
                }
            }
        }

        savedItems = savedItems.replaceAll("[^0-9,]", "");
        Log.i(TAG, "SPISAK ODABRANIH: " + savedItems);
        return savedItems;


    }


    private void LoadSelections() {
// if the selections were previously saved load them

        if (sharedpreferences.contains(MyPREFERENCES.toString())) {

            String savedItems = sharedpreferences.getString(MyPREFERENCES.toString(), "");
            selectedItems.addAll(Arrays.asList(savedItems.split(",")));

            int count = this.myList.getAdapter().getCount();

            for (int i = 0; i < count; i++) {
                String currentItem = (String) myList.getAdapter()
                        .getItem(i);
                if (selectedItems.contains(currentItem)) {
                    myList.setItemChecked(i, true);
                    Toast.makeText(getApplicationContext(),
                            "Curren Item: " + currentItem,
                            Toast.LENGTH_LONG).show();
                } else {
                    myList.setItemChecked(i, false);
                }

            }
        }
    }

   private void ClearSelections() {
// user has clicked clear button so uncheck all the items
        int count = this.myList.getAdapter().getCount();
        for (int i = 0; i < count; i++) {
            this.myList.setItemChecked(i, false);
        }
// also clear the saved selections
        SaveSelections();
    }

}

我的AsyncTask RegisterApp.java:

import java.io.IOException;
import java.net.URI;
import java.net.URISyntaxException;
import org.apache.http.client.ClientProtocolException;
import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import com.google.android.gms.gcm.GoogleCloudMessaging;
import android.content.Context;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.AsyncTask;
import android.os.Bundle;
import android.preference.PreferenceManager;
import android.util.Log;
import android.widget.Toast;


public class RegisterApp extends AsyncTask<Void, Void, String> {

 private static final String TAG = "GCMRelated";
 Context ctx;
 GoogleCloudMessaging gcm;
 String SENDER_ID = "980800840437";
 String regid = null;
 private int appVersion;
 public RegisterApp(Context ctx, GoogleCloudMessaging gcm, int appVersion){
  this.ctx = ctx;
  this.gcm = gcm;
  this.appVersion = appVersion;
 }


 @Override
 protected void onPreExecute() {
  super.onPreExecute();
 }


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


     String msg = "";
        try {
            if (gcm == null) {
                gcm = GoogleCloudMessaging.getInstance(ctx);
            }
            regid = gcm.register(SENDER_ID);
            msg = "Device registered, registration ID=" + regid;

            // You should send the registration ID to your server over HTTP,
            // so it can use GCM/HTTP or CCS to send messages to your app.
            // The request to your server should be authenticated if your app
            // is using accounts.
            sendRegistrationIdToBackend();

            // For this demo: we don't need to send it because the device
            // will send upstream messages to a server that echo back the
            // message using the 'from' address in the message.

            // Persist the regID - no need to register again.
            storeRegistrationId(ctx, regid);
        } catch (IOException ex) {
            msg = "Error :" + ex.getMessage();
            // If there is an error, don't just keep trying to register.
            // Require the user to click a button again, or perform
            // exponential back-off.
        }
        return msg;

 }


 private void storeRegistrationId(Context ctx, String regid) {
  final SharedPreferences prefs = ctx.getSharedPreferences(MainActivity.class.getSimpleName(),
             Context.MODE_PRIVATE);
     Log.i(TAG, "Saving regId on app version " + appVersion);
     SharedPreferences.Editor editor = prefs.edit();
     editor.putString("registration_id", regid);
     editor.putInt("appVersion", appVersion);
     editor.commit();

 }




    private void sendRegistrationIdToBackend() throws IOException {

        URL obj = new URL("http://www.example.com/push/?device_token="+regid+"&channels_id="+STRINGFROMACTIVITY);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();
        con.setRequestMethod("GET");
        con.setRequestProperty("Content-Type", "application/x-www-form-urlencoded;charset=UTF-8");
        int responseCode = con.getResponseCode();
        System.out.println("GET Response Code :: " + responseCode);
        if (responseCode == HttpURLConnection.HTTP_OK) { // success
            BufferedReader in = new BufferedReader(new InputStreamReader(
                    con.getInputStream()));
            String inputLine;
            StringBuffer response = new StringBuffer();

            while ((inputLine = in.readLine()) != null) {
                response.append(inputLine);
            }
            in.close();

            // print result
            System.out.println(response.toString());

            Log.i(TAG, "OVO SAM POSLAO " + savedItems);

        } else {
            System.out.println("GET request not worked");
        }

    }



 @Override
 protected void onPostExecute(String result) {
  super.onPostExecute(result);
  Toast.makeText(ctx, "Registration Completed. Now you can see the notifications", Toast.LENGTH_SHORT).show();
  Log.v(TAG, result);
 }
}

Answer 1

您可以在构造函数中将 STRINGFROMACTIVITY 从 Activity 传递到 AsyncTask。例如:在您的 Activity 中，

new RegisterApp(STRINGFROMACTIVITY).execute();

在 AsycnTask(RegisterApp) 构造函数中，

String STRINGFROMACTIVITY;  //create string variable in RegisterApp
......
......

public RegisterApp(String STRINGFROMACTIVITY){
  this.STRINGFROMACTIVITY= STRINGFROMACTIVITY;
 }

查看您的代码，我发现您已经有 3 个参数从 Activity 传递到 Asyctask，例如 Context ctx、GoogleCloudMessaging gcm、int appVersion，现在字符串值应该是要传递的第四个参数。另外，您的 AsyncTask 应该传递这 4 个参数。