使用JsonReader类解析Json Android

yk9xbfzb  于 2023-01-06  发布在  Android
关注(0)|答案(1)|浏览(121)

我是一名新的Android开发人员，在使用JsonReader类解析JSON InputStream时遇到了问题。每当它到达reader.beginArray（）开始解析InputStream时，它就会崩溃。我使用http://developer.android.com/reference/android/util/JsonReader.html中的代码作为示例。有人能帮我解决这个问题吗？顺便说一下，我使用JsonReader类是因为我在其他调用中使用了大量文本。
我正在传递以下URL：---删除---

public class JSONParser {

    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";
    static JsonReader reader = null;
    // constructor
    public JSONParser() {

    }


    public List getJSONFromUrl(String url) throws IOException {

        // Making HTTP request

            // defaultHttpClient
            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpGet httpGet = new HttpGet(url);

            try {
            HttpResponse httpResponse = httpClient.execute(httpGet);
            HttpEntity httpEntity = httpResponse.getEntity();
            is = httpEntity.getContent(); 


        } catch (UnsupportedEncodingException e) {
            e.printStackTrace();
        } catch (ClientProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }





            try {
                reader = new JsonReader(new InputStreamReader(is, "UTF-8"));
            } catch (UnsupportedEncodingException e1) {
                // TODO Auto-generated catch block
                e1.printStackTrace();
            }

            List<Message> messages = new ArrayList<Message>();
            try {
            reader.beginArray();
            while (reader.hasNext()) {
              messages.add(readMessage(reader));
            }
            reader.endArray();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }

                return messages;



        // try parse the string to a JSON object

        // return JSON String
        //return reader;

    }


    public Message readMessage(JsonReader reader) throws IOException {
        long _id = -1;
        String topic_title = null;
        Integer sort_order = null;

        reader.beginObject();
         while (reader.hasNext()) {
           String name = reader.nextName();
           if (name.equals("id")) {
               _id = reader.nextLong();
           } else if (name.equals("topic_title")) {
               topic_title = reader.nextString();

           }           
           else if (name.equals("sort_order")) {
               sort_order = reader.nextInt();

           }
           else {
               reader.skipValue();
           }
         }
         reader.endObject();
         DataBaseHelper.getInstance().updateTopicOrder(_id, sort_order, topic_title);
        return new Message();
      }

}

下面是我的日志：

12-05 10:08:54.806: D/gralloc_goldfish(582): Emulator without GPU emulation detected.
12-05 10:08:56.367: D/dalvikvm(582): GC_CONCURRENT freed 146K, 3% free 10139K/10375K, paused 19ms+10ms
12-05 10:12:17.466: W/webcore(582): java.lang.Throwable: EventHub.removeMessages(int what = 107) is not supported before the WebViewCore is set up.
12-05 10:12:17.466: W/webcore(582):     at android.webkit.WebViewCore$EventHub.removeMessages(WebViewCore.java:1671)
12-05 10:12:17.466: W/webcore(582):     at android.webkit.WebViewCore$EventHub.access$7800(WebViewCore.java:920)
12-05 10:12:17.466: W/webcore(582):     at android.webkit.WebViewCore.removeMessages(WebViewCore.java:1783)
12-05 10:12:17.466: W/webcore(582):     at android.webkit.WebView.sendOurVisibleRect(WebView.java:2858)
12-05 10:12:17.466: W/webcore(582):     at android.webkit.ZoomManager.setZoomScale(ZoomManager.java:586)
12-05 10:12:17.466: W/webcore(582):     at android.webkit.ZoomManager.access$1700(ZoomManager.java:49)
12-05 10:12:17.466: W/webcore(582):     at android.webkit.ZoomManager$PostScale.run(ZoomManager.java:977)
12-05 10:12:17.466: W/webcore(582):     at android.os.Handler.handleCallback(Handler.java:605)
12-05 10:12:17.466: W/webcore(582):     at android.os.Handler.dispatchMessage(Handler.java:92)
12-05 10:12:17.466: W/webcore(582):     at android.os.Looper.loop(Looper.java:137)
12-05 10:12:17.466: W/webcore(582):     at android.app.ActivityThread.main(ActivityThread.java:4340)
12-05 10:12:17.466: W/webcore(582):     at java.lang.reflect.Method.invokeNative(Native Method)
12-05 10:12:17.466: W/webcore(582):     at java.lang.reflect.Method.invoke(Method.java:511)
12-05 10:12:17.466: W/webcore(582):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
12-05 10:12:17.466: W/webcore(582):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
12-05 10:12:17.466: W/webcore(582):     at dalvik.system.NativeStart.main(Native Method)
12-05 10:12:19.146: D/dalvikvm(582): GC_CONCURRENT freed 179K, 4% free 10370K/10695K, paused 5ms+8ms
12-05 10:12:19.616: W/dalvikvm(582): threadid=13: thread exiting with uncaught exception (group=0x409961f8)
12-05 10:12:19.672: E/AndroidRuntime(582): FATAL EXCEPTION: AsyncTask #2
12-05 10:12:19.672: E/AndroidRuntime(582): java.lang.RuntimeException: An error occured while executing doInBackground()
12-05 10:12:19.672: E/AndroidRuntime(582):  at android.os.AsyncTask$3.done(AsyncTask.java:278)
12-05 10:12:19.672: E/AndroidRuntime(582):  at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
12-05 10:12:19.672: E/AndroidRuntime(582):  at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
12-05 10:12:19.672: E/AndroidRuntime(582):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
12-05 10:12:19.672: E/AndroidRuntime(582):  at java.util.concurrent.FutureTask.run(FutureTask.java:137)
12-05 10:12:19.672: E/AndroidRuntime(582):  at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
12-05 10:12:19.672: E/AndroidRuntime(582):  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
12-05 10:12:19.672: E/AndroidRuntime(582):  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
12-05 10:12:19.672: E/AndroidRuntime(582):  at java.lang.Thread.run(Thread.java:856)
12-05 10:12:19.672: E/AndroidRuntime(582): Caused by: java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT
12-05 10:12:19.672: E/AndroidRuntime(582):  at android.util.JsonReader.expect(JsonReader.java:310)
12-05 10:12:19.672: E/AndroidRuntime(582):  at android.util.JsonReader.beginArray(JsonReader.java:277)
12-05 10:12:19.672: E/AndroidRuntime(582):  at com.gotquestions.gqandapp.util.JSONParser.readMessagesArray(JSONParser.java:82)
12-05 10:12:19.672: E/AndroidRuntime(582):  at com.gotquestions.gqandapp.util.JSONParser.getJSONFromUrl(JSONParser.java:73)
12-05 10:12:19.672: E/AndroidRuntime(582):  at com.gotquestions.gqandapp.ac.UpdaterActivity$updateTopics.doInBackground(UpdaterActivity.java:108)
12-05 10:12:19.672: E/AndroidRuntime(582):  at com.gotquestions.gqandapp.ac.UpdaterActivity$updateTopics.doInBackground(UpdaterActivity.java:1)
12-05 10:12:19.672: E/AndroidRuntime(582):  at android.os.AsyncTask$2.call(AsyncTask.java:264)
12-05 10:12:19.672: E/AndroidRuntime(582):  at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
12-05 10:12:19.672: E/AndroidRuntime(582):  ... 5 more
12-05 10:12:24.938: I/Process(582): Sending signal. PID: 582 SIG: 9
12-05 10:14:39.988: W/ActivityThread(645): Application com.gotquestions.gqandapp is waiting for the debugger on port 8100...
12-05 10:14:40.097: I/System.out(645): Sending WAIT chunk
12-05 10:14:40.137: I/dalvikvm(645): Debugger is active
12-05 10:14:40.216: I/System.out(645): Debugger has connected
12-05 10:14:40.216: I/System.out(645): waiting for debugger to settle...
12-05 10:14:40.416: I/System.out(645): waiting for debugger to settle...
12-05 10:14:40.617: I/System.out(645): waiting for debugger to settle...
12-05 10:14:40.817: I/System.out(645): waiting for debugger to settle...
12-05 10:14:41.027: I/System.out(645): waiting for debugger to settle...
12-05 10:14:41.228: I/System.out(645): waiting for debugger to settle...
12-05 10:14:41.427: I/System.out(645): waiting for debugger to settle...
12-05 10:14:41.627: I/System.out(645): waiting for debugger to settle...
12-05 10:14:41.827: I/System.out(645): waiting for debugger to settle...
12-05 10:14:42.052: I/System.out(645): waiting for debugger to settle...
12-05 10:14:42.247: I/System.out(645): waiting for debugger to settle...
12-05 10:14:42.462: I/System.out(645): waiting for debugger to settle...
12-05 10:14:42.674: I/System.out(645): waiting for debugger to settle...
12-05 10:14:42.881: I/System.out(645): waiting for debugger to settle...
12-05 10:14:43.086: I/System.out(645): debugger has settled (1352)
12-05 10:14:46.566: D/gralloc_goldfish(645): Emulator without GPU emulation detected.
12-05 10:14:47.616: D/dalvikvm(645): GC_CONCURRENT freed 149K, 3% free 10138K/10375K, paused 6ms+6ms
12-05 10:19:45.851: D/dalvikvm(645): Debugger has detached; object registry had 594 entries
12-05 10:21:11.577: W/ActivityThread(707): Application com.gotquestions.gqandapp is waiting for the debugger on port 8100...
12-05 10:21:11.668: I/System.out(707): Sending WAIT chunk
12-05 10:21:11.677: I/dalvikvm(707): Debugger is active
12-05 10:21:11.747: I/System.out(707): Debugger has connected
12-05 10:21:11.747: I/System.out(707): waiting for debugger to settle...
12-05 10:21:11.987: I/System.out(707): waiting for debugger to settle...
12-05 10:21:12.197: I/System.out(707): waiting for debugger to settle...
12-05 10:21:12.397: I/System.out(707): waiting for debugger to settle...
12-05 10:21:12.597: I/System.out(707): waiting for debugger to settle...
12-05 10:21:12.799: I/System.out(707): waiting for debugger to settle...
12-05 10:21:13.007: I/System.out(707): waiting for debugger to settle...
12-05 10:21:13.207: I/System.out(707): waiting for debugger to settle...
12-05 10:21:13.407: I/System.out(707): waiting for debugger to settle...
12-05 10:21:13.607: I/System.out(707): waiting for debugger to settle...
12-05 10:21:13.820: I/System.out(707): waiting for debugger to settle...
12-05 10:21:14.017: I/System.out(707): waiting for debugger to settle...
12-05 10:21:14.227: I/System.out(707): waiting for debugger to settle...
12-05 10:21:14.427: I/System.out(707): waiting for debugger to settle...
12-05 10:21:14.626: I/System.out(707): waiting for debugger to settle...
12-05 10:21:14.864: I/System.out(707): waiting for debugger to settle...
12-05 10:21:15.078: I/System.out(707): debugger has settled (1364)
12-05 10:21:18.457: D/gralloc_goldfish(707): Emulator without GPU emulation detected.
12-05 10:21:19.567: D/dalvikvm(707): GC_CONCURRENT freed 151K, 3% free 10136K/10375K, paused 7ms+7ms
12-05 10:21:28.467: D/dalvikvm(707): GC_CONCURRENT freed 160K, 3% free 10401K/10695K, paused 6ms+8ms
JSON

1条答案

按热度按时间
h79rfbju

h79rfbju1#

你的日志上说
12月5日10时12分19秒672 E/安卓运行时（582）：原因：java. lang.非法状态异常：应为BEGIN_ARRAY，但实际为BEGIN_OBJECT
在Json格式中，"{}"是对象，"[]"是数组
看看你的json文件，我想它是从一个对象开始的。如果是从对象开始的，把你的代码行改为从读一个对象开始，而不是数组。

try {
        reader.beginObject();
        while (reader.hasNext()) {
          messages.add(readMessage(reader));
        }
        reader.endObject();
        }

注意：使用完后关闭流，常用的方法是将代码放入finally块。

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