Android，JSON，PHP。 无法从数据库检索数据

Question

有人可以告诉我我的代码有什么问题吗？ 我无法从数据库将数据检索到ListView中。 Logcat说“公告没有价值”。 请在这里我是新的。 提前致谢

Announcement.java

package com.example.androidtablayout;

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

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

import android.app.Activity;
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.Button;
import android.widget.ListAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;

public class Announcements extends ListActivity {

//  Variables
JSONArray jsonarray;
ListView listview;

ArrayList<HashMap<String, String>> arraylist;
ProgressDialog mProgressDialog;

JSONParser jsonParser = new JSONParser();
String email;
SessionManager session;
String[] services;

Button btnLogout;
String username;

private String url = "http://10.0.3.2/sunshine-ems/announcement.php";

// ALL JSON node names
private static final String ANNOUNCEMENT_ID = "announcement_id";
private static final String ANNOUNCEMENT_DATE = "date";
private static final String ANNOUNCEMENT_TITLE = "title";

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.announc);

    session = new SessionManager(getApplicationContext());
    username = session.getUsername();
    // get listview
    ListView lv = getListView();

    lv.setOnItemClickListener(new android.widget.AdapterView.OnItemClickListener() {
        public void onItemClick(AdapterView<?> arg0, View view, int arg2, long arg3) {

            Intent i = new Intent(getApplicationContext(),Single_List.class);

            String transaction_id = ((TextView) view.findViewById(R.id.transac_id)).getText().toString();

            i.putExtra("announcement_id", transaction_id);


            startActivity(i);
        }
    });
    btnLogout = (Button) findViewById(R.id.btnLogout);
    btnLogout.setOnClickListener(new View.OnClickListener() {

        public void onClick(View view) {
            // Launching All products Activity
            session.logoutUser();
            Intent i = new Intent(getApplicationContext(), Login.class);
            startActivity(i);

        }
    });
    new DownloadJSON().execute();
}

// DownloadJSON AsyncTask
private class DownloadJSON extends AsyncTask<String, String, String> {

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        mProgressDialog = new ProgressDialog(Announcements.this);
        mProgressDialog.setTitle("Loading Services");
        mProgressDialog.setMessage("Loading...");
        mProgressDialog.setIndeterminate(false);
        mProgressDialog.show();
    }

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

        List<NameValuePair> params1 = new ArrayList<NameValuePair>();
        params1.add(new BasicNameValuePair("username", username));

        JSONObject json = jsonParser.makeHttpRequest(url, "POST", params1);

        Log.e("Check JSON ", json.toString());

        // Create the array
        arraylist = new ArrayList<HashMap<String, String>>();

        try {               
            int success = json.getInt("success");

            if (success == 1) {

            // Locate the array name
            jsonarray = json.getJSONArray("announcements");
            for (int i = 0; i < jsonarray.length(); i++) {

                json = jsonarray.getJSONObject(i);
                String a_id = json.optString(ANNOUNCEMENT_ID);
                String a_date = json.getString(ANNOUNCEMENT_DATE);
                String a_title = json.getString(ANNOUNCEMENT_TITLE);

                // Retrive JSON Objects
                HashMap<String, String> map = new HashMap<String, String>();
                map.put(ANNOUNCEMENT_ID, a_id);
                map.put(ANNOUNCEMENT_TITLE, a_title);
                map.put(ANNOUNCEMENT_DATE, a_date);


                // Set the JSON Objects into the array
                arraylist.add(map);
                }
            }
        } catch (JSONException e) {
            Log.e("Error", e.getMessage());
            e.printStackTrace();
        }
        return null;
    }

    @Override
    protected void onPostExecute(String file_url) {
        mProgressDialog.dismiss();
        // updating UI from Background Thread
        runOnUiThread(new Runnable() {
            public void run() {

                /**
                 * Updating parsed JSON data into ListView
                 * */
                ListAdapter adapter = new SimpleAdapter(
                        Announcements.this, arraylist,
                        R.layout.listview_services, new String[] {
                                ANNOUNCEMENT_ID, ANNOUNCEMENT_TITLE, ANNOUNCEMENT_DATE },
                        new int[] { R.id.transac_id, R.id.txt_service,
                                R.id.txt_date });
                // updating listview
                setListAdapter(adapter);

            }
        });

    }
}

}

announcement.php

<?php

$response = array();
require_once __DIR__ . '/db_connect.php';
$db = new DB_CONNECT();

$username = $_POST['username'];
$query_dept = mysql_query("SELECT department FROM accounts WHERE username =           $username")  or die(mysql_error());
$row = mysql_fetch_assoc($query_dept);
$dept = $row['department'];


$result = mysql_query("SELECT * FROM announcement WHERE receiver=$dept") or die(mysql_error());

// check for empty result
if (mysql_num_rows($result) > 0) {
// looping through all results
// products node
$response["announcements"] = array();

while ($row = mysql_fetch_array($result)) {
    // temp user array
    $announcement = array();
    $announcement["announcement_id"] = $row["announcement_id"];
    $announcement["title"] = $row["title"];
    $announcement["date"] = $row["date"];

    // push single product into final response array
    array_push($response["announcements"], $announcement);
}
// success
$response["success"] = 1;

// echoing JSON response
echo json_encode($response);
} else {
// no products found
$response["success"] = 0;
$response["message"] = "No Announcement found";

// echo no users JSON
echo json_encode($response);
}
?>

Answer 1

• “选择部门来自帐户的用户名='”。$ username。“”;“；”

• “ SELECT * FROM公告WHERE接收者='”。$ dept。“';”

  检查查询是否正确执行