无法从MySQL表检索与特定“ uid”匹配的数据

Question

我试图学习有关MySQL的更多信息，并使用Java（在Android上）从WAMS服务器上的数据库访问和检索信息。我的应用程序的设置方式是它具有一个初始登录屏幕，该屏幕还捕获（从另一个表中）登录的用户名的“
uid”并进行存储。

登录后（功能正常-
我设置了一个敬酒通知，其中显示了登录用户的检索到的用户名和uid），它会转到一个新屏幕（dashboard.xml），该屏幕具有一个TextView字段设置来显示检索到的数据（来自与存储的“
uid”关联的表）。这是我要从中提取数据的表：

http://db.tt/4izVQuGB

现在，我已经设置了一个PHP文件，该文件在我的数据库中查询与特定“ uid”关联的行。我已经使用HTML表单测试了此文件。

$connect = mysql_connect($dbhost, $dbuser, $dbpass) or die("connection error");
mysql_select_db($dbdb)or die("database selection error");

//Retrieve the User ID
$uid = $_POST['uid'];

//Query
$query = mysql_query("SELECT * FROM node WHERE uid='$uid' AND type='goal'");

//store # of rows returned
$num_rows = mysql_num_rows($query);

if ($num_rows >= 1) {
    while($results=mysql_fetch_assoc($query)) {
        //Store the returned data into a variable
        $output = $results;

        //encode the returned data in JSON format
        echo json_encode($output);
    }
    mysql_close();
}

通过使用uid值1测试PHP文件得到的结果是：

{“nid”:”1”,”vid”:”1”,”type”:”goal”,”language”:”“,”title”:”test”,”uid”:”1”,”status”:”1”,”created”:”1342894493”,”changed”:”1342894493”,”comment”:”2”,”promote”:”1”,”moderate”:”0”,”sticky”:”1”,”tnid”:”0”,”translate”:”0”}

{“nid”:”2”,”vid”:”2”,”type”:”goal”,”language”:”“,”title”:”test2”,”uid”:”1”,”status”:”1”,”created”:”1342894529”,”changed”:”1342894529”,”comment”:”2”,”promote”:”1”,”moderate”:”0”,”sticky”:”1”,”tnid”:”0”,”translate”:”0”}

{“nid”:”5”,”vid”:”5”,”type”:”goal”,”language”:”“,”title”:”run”,”uid”:”1”,”status”:”1”,”created”:”1343506987”,”changed”:”1343506987”,”comment”:”2”,”promote”:”1”,”moderate”:”0”,”sticky”:”1”,”tnid”:”0”,”translate”:”0”}

{“nid”:”9”,”vid”:”9”,”type”:”goal”,”language”:”“,”title”:”run to the
hills”,”uid”:”1”,”status”:”1”,”created”:”1343604338”,”changed”:”1343605100”,”comment”:”2”,”promote”:”0”,”moderate”:”0”,”sticky”:”0”,”tnid”:”0”,”translate”:”0”}

现在，我写了一些Android代码来设置httppost，并应该在数据库表中检索“标题”。我知道这是错误的（显然是因为它不起作用），但是对于下一步该做什么我感到困惑。

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.json.JSONObject;
import android.app.Activity;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;

public class Dashboard extends Activity implements OnClickListener {

    // variable declarations
    String uid = "1";

    // create textview to display retrieved data
    TextView display;

    HttpClient httpclient;
    HttpPost httppost;
    HttpResponse httpresponse;
    HttpEntity httpentity;

    ArrayList<NameValuePair> resultArray;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.dashboard);
        display = (TextView) findViewById(R.id.test);

        // initialize HttpClient
        httpclient = new DefaultHttpClient();

        // initialize HttpPost
        httppost = new HttpPost("http://192.168.1.112/android/fetch.php");

        try {
        // Create new List
        List<NameValuePair> resultList = new ArrayList<NameValuePair>();
        resultList.add(new BasicNameValuePair("uid", uid));

        httppost.setEntity(new UrlEncodedFormEntity(resultList));

        httpresponse = httpclient.execute(httppost);

        httpentity = httpresponse.getEntity();

        InputStream instream = entity.getContent();

        try {
                            // store incoming stream in an array
            JSONArray jArray = new JSONArray(streamToString(instream));
            JSONObject jData = null;

            for (int i = 0; i < jArray.length(); i++) {
                jData = jArray.getJSONObject(i);
                String goals = jData.getString("title");
                display.setText(goals);
            }
        //} catch (JSONException e) {
            //Toast.makeText(this, "No entries found", Toast.LENGTH_LONG).show();
        } catch (Exception e) {
            Toast.makeText(this, e.toString(), Toast.LENGTH_LONG)
                    .show();
        }

    } catch (Exception e) {
        e.printStackTrace();
        Notifications error = new Notifications();
        error.userPassErrorDialog();
    }

}

private static String streamToString(InputStream is) {

    BufferedReader reader = new BufferedReader(new InputStreamReader(is));
    StringBuilder sb = new StringBuilder();

    String line = null;
    try {
        while ((line = reader.readLine()) != null) {
            sb.append(line + "\n");
        }
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            is.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return sb.toString();
}

public void onClick(View v) {
    // TODO Auto-generated method stub

}

}

在Android模拟器中进行测试时，出现以下错误：

http://db.tt/2vg9MqYh

任何帮助或建议，将不胜感激。

Answer 1

在您的Android应用中，您需要一个JSONArray：

// store incoming stream in an array
JSONArray jArray = new JSONArray(streamToString(instream));

但是，在您的PHP文件中，您仅输出多个单独的JSON对象，而不是实际数组。我认为，您应该首先从数据库中的PHP数组中收集所有项目，然后再对其进行编码和输出一次。

我的PHP技巧有点生锈，但是我希望这一技巧能起作用：

//store # of rows returned
$num_rows = mysql_num_rows($query);

if ($num_rows >= 1) {
    $output = array();

    while($results = mysql_fetch_assoc($query)) {
        // append row to output
        $output[] = results
    }

    mysql_close();  // shouldn't that be outside the if block?

    //encode the returned data in JSON format
    echo json_encode($output);
}

我希望输出是这样的（也许没有缩进）：

[
    {"nid":"1","vid":"1","type":"goal","language":"","title":"test","uid":"1","status":"1","created":"1342894493","changed":"1342894493","comment":"2","promote":"1","moderate":"0","sticky":"1","tnid":"0","translate":"0"},
    {"nid":"2","vid":"2","type":"goal","language":"","title":"test2","uid":"1","status":"1","created":"1342894529","changed":"1342894529","comment":"2","promote":"1","moderate":"0","sticky":"1","tnid":"0","translate":"0"},
    {"nid":"5","vid":"5","type":"goal","language":"","title":"run","uid":"1","status":"1","created":"1343506987","changed":"1343506987","comment":"2","promote":"1","moderate":"0","sticky":"1","tnid":"0","translate":"0"},
    {"nid":"9","vid":"9","type":"goal","language":"","title":"run to the hills","uid":"1","status":"1","created":"1343604338","changed":"1343605100","comment":"2","promote":"0","moderate":"0","sticky":"0","tnid":"0","translate":"0"}
]