将android连接到移动数据库时出现JSONArray错误

Question

我正在尝试使用 android 连接到我的在线数据库。在遵循教程后，我想出了这段代码：

package com.example.helloandroid;

import java.io.BufferedReader;
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.json.*;

import android.app.Activity;
import android.os.Bundle;
import android.util.Log;

public class HelloAndroid extends Activity {
    JSONArray jArray;
    String result = null;
    InputStream is = null;
    StringBuilder sb=null;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        ArrayList<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>();
        try{
            HttpClient httpclient = new DefaultHttpClient();
            HttpPost httppost = new HttpPost("http://192.168.1.4/~jasptack/Software%20engineering/connector.php");
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));
            HttpResponse response = httpclient.execute(httppost);
            HttpEntity entity = response.getEntity();
            is = entity.getContent();
            }catch(Exception e){
                Log.e("log_tag", "Error in http connection"+e.toString());
           }

        //convert response to string
        try{
              BufferedReader reader = new BufferedReader(new InputStreamReader(is,"iso-8859-1"),8);
               sb = new StringBuilder();
               sb.append(reader.readLine() + "\n");
               String line="0";
               while ((line = reader.readLine()) != null) {
                              sb.append(line + "\n");
               }
               is.close();
               result=sb.toString();
               }catch(Exception e){
                      Log.e("log_tag", "Error converting result "+e.toString());
               }
      //parse json data
        try{
                JSONArray jArray = new JSONArray(result);
                for(int i=0;i<jArray.length();i++){
                        JSONObject json_data = jArray.getJSONObject(i);
                        Log.i("log_tag","x-co: "+json_data.getInt("x-coordinaat")+
                                ", straat: "+json_data.getString("straat")
                        );
                }
        }catch(JSONException e){
                Log.e("log_tag", "Error parsing data "+e.toString());
        }
    }
}

执行此操作时，出现以下错误： 12-04 23:25:07.711：E/log_tag(353)：解析数据时出错 org.json.JSONException：值

有人可以帮忙吗？谢谢！

Answer 1

如果 JSON 字符串格式错误，就会发生这种情况。确保String result 是有效的JSONArray（应该以'['开头）。此外，您可以尝试将result 映射到JSONObject。如果这些都很好，则JSONArray 中的元素之一格式不正确。

Answer 2

我曾经尝试解析我的 Web 服务返回的 JSON 字符串。这是我所做的：

我从网络服务得到的响应是：

{"checkrecord":[{"rollno":"abc2","percentage":40,"attended":12,"missed":34}],"Table1":[]}

为了解析，我做了以下操作：

      JSONObject jsonobject = new JSONObject(result);
      JSONArray array = jsonobject.getJSONArray("checkrecord"); 
      int max = array.length();
      for (int j = 0; j < max; j++) 
   {
      JSONObject obj = array.getJSONObject(j);
      JSONArray names = obj.names();

     for (int k = 0; k < names.length(); k++) 
   {
      String name = names.getString(k);
      String value= obj.getString(name);  

   }

我的 JSONObject 看起来像这样：

{"Table1":[],"checkrecord":[{"missed":34,"attended":12,"percentage":40,"rollno":"abc2"}]}

这就是@500865 试图提出的建议。我刚刚给你一个代码示例。首先检查您的结果并确定它是否有效。还要检查 JSONArray 结果。 如果可能，请在此处发布。

希望对你有帮助

干杯