java - 每当我向远程数据库添加内容时如何通知应用程序用户？

Question

我开发了我的第一个 Android 应用程序。 该应用程序的作用:我使用网站上的新结果更新 mysql 数据库，并且 android 应用程序从 mysql 获取相同的数据。我正在使用 JSON。

我想要它做什么:我希望它通知用户结果已更新。它可以是及时通知，也可以是正常通知。不要紧。我只是希望用户在我更新数据库后立即知道这一点。

代码供您引用: 1) 在应用程序内显示结果的 Java 代码。

  package in.thespl.spl.notifications;

  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;

  import org.apache.http.NameValuePair;
  import org.json.JSONArray;
  import org.json.JSONException;
  import org.json.JSONObject;

  import android.app.ListActivity;
  import android.app.ProgressDialog;
  import android.content.Intent;
  import android.os.AsyncTask;
  import android.os.Bundle;
  import android.util.Log;
  import android.view.View;
  import android.widget.AdapterView;
  import android.widget.AdapterView.OnItemClickListener;
  import android.widget.ListAdapter;
  import android.widget.ListView;
  import android.widget.SimpleAdapter;
  import android.widget.TextView;

  public class AllResultsActivity extends ListActivity {

// Progress Dialog
private ProgressDialog pDialog;

// Creating JSON Parser object
JSONParser jParser = new JSONParser();

ArrayList<HashMap<String, String>> productsList;

// url to get all products list
private static String url_all_products = "http://mydomain.in/fetchresult.php";

// JSON Node names
private static final String TAG_SUCCESS = "success";
private static final String TAG_PRODUCTS = "result";
private static final String TAG_PID = "rid";
private static final String TAG_NAME = "rname";
private static final String TAG_INFO = "rinfo";

// products JSONArray
JSONArray products = null;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.all_products);

    // Hashmap for ListView
    productsList = new ArrayList<HashMap<String, String>>();

    // Loading products in Background Thread
    new LoadAllProducts().execute();

    // Get listview
    ListView lv = getListView();

    // on seleting single product
    // launching Edit Product Screen
    lv.setOnItemClickListener(new OnItemClickListener() {

        @Override
        public void onItemClick(AdapterView<?> parent, View view,
                int position, long id) {
            // getting values from selected ListItem
            String pid = ((TextView) view.findViewById(R.id.rid)).getText()
                    .toString();

            // Starting new intent
            Intent in = new Intent(getApplicationContext(),
                    AllResultsActivity.class);
            // sending pid to next activity
            in.putExtra(TAG_PID, pid);

            // starting new activity and expecting some response back
            startActivityForResult(in, 100);
        }
    });

}

// Response from Edit Product Activity
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    super.onActivityResult(requestCode, resultCode, data);
    // if result code 100
    if (resultCode == 100) {
        // if result code 100 is received
        // means user edited/deleted product
        // reload this screen again
        Intent intent = getIntent();
        finish();
        startActivity(intent);
    }

}

/**
 * Background Async Task to Load all product by making HTTP Request
 * */
class LoadAllProducts extends AsyncTask<String, String, String> {

    /**
     * Before starting background thread Show Progress Dialog
     * */
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(AllResultsActivity.this);
        pDialog.setMessage("Loading results. Please wait...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(false);
        pDialog.show();
    }

    /**
     * getting All products from url
     * */
    protected String doInBackground(String... args) {
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();
        // getting JSON string from URL
        JSONObject json = jParser.makeHttpRequest(url_all_products, "GET", params);

        // Check your log cat for JSON reponse
        Log.d("All Products: ", json.toString());

        try {
            // Checking for SUCCESS TAG
            int success = json.getInt(TAG_SUCCESS);

            if (success == 1) {
                // products found
                // Getting Array of Products
                products = json.getJSONArray(TAG_PRODUCTS);

                // looping through All Products
                for (int i = 0; i < products.length(); i++) {
                    JSONObject c = products.getJSONObject(i);

                    // Storing each json item in variable
                    String id = c.getString(TAG_PID);
                    String name = c.getString(TAG_NAME);
                    String info = c.getString(TAG_INFO);
                    // creating new HashMap
                    HashMap<String, String> map = new HashMap<String, String>();

                    // adding each child node to HashMap key => value
                    map.put(TAG_PID, id);
                    map.put(TAG_NAME, name);
                    map.put(TAG_INFO, info);

                    // adding HashList to ArrayList
                    productsList.add(map);
                }
            } else {
                // no products found
                // Launch Add New product Activity
               // Intent i = new Intent(getApplicationContext(),
                //       AllResultsActivity.class);
                // Closing all previous activities
                //i.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
               // startActivity(i);
            }
        } catch (JSONException e) {
            e.printStackTrace();
        }

        return null;
    }

    /**
     * After completing background task Dismiss the progress dialog
     * **/
    protected void onPostExecute(String file_url) {
        // dismiss the dialog after getting all products
        pDialog.dismiss();
        // updating UI from Background Thread
        runOnUiThread(new Runnable() {
            public void run() {
                /**
                 * Updating parsed JSON data into ListView
                 * */
                ListAdapter adapter = new SimpleAdapter(
                        AllResultsActivity.this, productsList,
                        R.layout.list_item, new String[] { TAG_PID,
                                TAG_NAME, TAG_INFO },
                        new int[] { R.id.rid, R.id.rname, R.id.rinfo});
                // updating listview
                setListAdapter(adapter);
            }
         });

       }

   }
  }

知道如何在此添加通知功能吗？

Answer 1

您有多种方法可以做到这一点。

第一种方法是轮询服务器以请求更新。 这个解决方案并不是很有效，并且必须选择很多参数: 更新时间->将影响电池和 react 性。

第二种方法是使用 Google Cloud Messaging。它提供了一种将数据从服务器推送到用户的解决方案。实现起来非常简单。 (花了我几个小时)。 安卓文档。 http://developer.android.com/guide/google/gcm/index.html 第二种方法可以优化电池，即使您的应用程序关闭，您也可以收到推送。

选择更适合您需求的方式。

希望对您有帮助。