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从昨天开始，我一直在尝试让我的应用程序获取一些由 PHP 文件生成的 JSON 数据，然后在列表视图中显示这些数据。

PHP 文件使用 encode 方法对数据进行编码：

echo json_encode($results);

从浏览器视图源查看file.php 生成的 JSON 如下所示：

["","CSD1939","CSD1939"]

JSONLint （一个很棒的工具）将其验证为正确的 JSON 格式。

当我尝试使用我的应用程序从 web 服务获取此 JSON 时，我首先将其作为字符串获取，但我无法将其传递给适配器并使其正确显示。

直到现在我才设法创建一个显示字符串数组的列表视图。

获取此 JSON 数据并将其显示在列表中的最佳方法是什么。

    package com.example.ams;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.StatusLine;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.content.Context;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;

public class ViewClasses extends Activity {

    @SuppressLint("NewApi")
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.view_classes);

        new GetInfo().execute();

        // ==============Functionality Start====================
        // final ListView listview = (ListView) findViewById(R.id.listview);
    }

    private class GetInfo extends AsyncTask<Void, Void, String> {

        protected String doInBackground(Void... params) {
            // Fetch the JSON from the web and we pass it as a string to
            // the ON POST EXECUTE method
            StringBuilder builder = new StringBuilder();
            HttpClient client = new DefaultHttpClient();
            HttpGet httpGet = new HttpGet(
                    "file.php?get=XXX");
            try {
                HttpResponse response = client.execute(httpGet);
                StatusLine statusLine = response.getStatusLine();
                int statusCode = statusLine.getStatusCode();
                if (statusCode == 200) {
                    HttpEntity entity = response.getEntity();
                    InputStream content = entity.getContent();
                    BufferedReader reader = new BufferedReader(
                            new InputStreamReader(content));
                    String line;
                    while ((line = reader.readLine()) != null) {
                        builder.append(line);
                    }
                } else {
                    Log.e(this.toString(), "Failed to download file");
                }
            } catch (ClientProtocolException e) {
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return builder.toString();
        }

        protected void onPostExecute(String result) {
            // Here it should turn it into a JSON and then display it in a list.
            // Gets the list view
            final ListView listview = (ListView) findViewById(R.id.listview);

            // Converts the String to a JSON array
            System.out.println(result);
            JSONArray jsonArray;
            try {
                System.out.println(result);
                jsonArray = new JSONArray(result);

                Log.i(ViewClasses.class.getName(), "Number of entries "
                        + jsonArray.length());
                for (int i = 0; i < jsonArray.length(); i++) {
                    JSONObject jsonObject = jsonArray.getJSONObject(i);
                    Log.i(ViewClasses.class.getName(),
                            jsonObject.getString("text"));

                    // Converts JSON array to Java Array
                    final ArrayList<String> list = new ArrayList<String>();
                    // values instead of jsonArray
                    if (jsonArray != null) {
                        int len = jsonArray.length();
                        for (int i1 = 0; i1 < len; i1++) {
                            list.add(jsonArray.get(i).toString());
                        }
                    }
                    final StableArrayAdapter adapter = new StableArrayAdapter(
                            getApplicationContext(),
                            android.R.layout.simple_list_item_1, list);
                    listview.setAdapter(adapter);
                }
            } catch (JSONException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
    }

    private class StableArrayAdapter extends ArrayAdapter<String> {

        HashMap<String, Integer> mIdMap = new HashMap<String, Integer>();

        public StableArrayAdapter(Context context, int textViewResourceId,
                List<String> objects) {
            super(context, textViewResourceId, objects);
            for (int i = 0; i < objects.size(); ++i) {
                mIdMap.put(objects.get(i), i);
            }
        }

        @Override
        public long getItemId(int position) {
            String item = getItem(position);
            return mIdMap.get(item);
        }

        @Override
        public boolean hasStableIds() {
            return true;
        }

    }
}

我的布局 XML 文件如下所示

<ListView xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/listview"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

运行此代码，我得到一个空白屏幕。

任何帮助，指针，提示将不胜感激

4

1 回答 1

1

它只是返回JSONArray，Strings所以你不应该JSONObject从中创建。

   JSONObject jsonObject = jsonArray.getJSONObject(i);

这将导致ExceptionasJSONArray不包含JSONObjects.

所以像这样解析

ArrayList<String> list = new ArrayList<String>();
for (int i = 0; i < jsonArray.length(); i++) {
  list.add(jsonArray.get(i).toString());
}
于 2013-04-23T15:14:20.593 回答