java - Gson输出com.google.gson.JsonSyntaxException:java.io.EOFException:第1行第501列的输入结束

我一直在使用Gson在API中解析JSON，以便在我的应用中使用。这是JSON输出的示例：

{"getdashboarddata":{"version":"1.0.0","runtime":492.3939704895,"data":{"raw":{"personal":{"hashrate":0},"pool":{"hashrate":1705841},"network":{"hashrate":41430764.301,"esttimeperblock":94.464466565347,"nextdifficulty":578.78109116,"blocksuntildiffchange":1}},"personal":{"hashrate":0,"sharerate":"0.0000","sharedifficulty":0,"shares":{"valid":0,"invalid":0,"invalid_percent":0,"unpaid":0},"estimates":{"block":0,"fee":0,"donation":0,"payout":0}},"pool":{"info":{"name":"RAPIDHASH","currency":"DOGE"},"workers":2199,"hashrate":1.705841,"shares":{"valid":1866290,"invalid":15564,"invalid_percent":0.83,"estimated":1866214,"progress":100},"price":"0.00000073","difficulty":32,"target_bits":21},"system":{"load":[0.1,0.25,0.29]},"network":{"hashrate":41.430764301,"difficulty":911.23745057,"block":235378,"esttimeperblock":94.46,"nextdifficulty":578.78109116,"blocksuntildiffchange":1}}}}

这是logcat：

05-25 17:12:00.230  24143-24159/io.kd.figgycity50.mpos.mposchecker E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1
Process: io.kd.figgycity50.mpos.mposchecker, PID: 24143
java.lang.RuntimeException: An error occured while executing doInBackground()
        at android.os.AsyncTask$3.done(AsyncTask.java:300)
        at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
        at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
        at java.util.concurrent.FutureTask.run(FutureTask.java:242)
        at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
        at java.lang.Thread.run(Thread.java:841)
 Caused by: com.google.gson.JsonSyntaxException: java.io.EOFException: End of input at line 1 column 501
        at com.google.gson.Gson.fromJson(Gson.java:813)
        at com.google.gson.Gson.fromJson(Gson.java:768)
        at com.google.gson.Gson.fromJson(Gson.java:717)
        at com.google.gson.Gson.fromJson(Gson.java:689)
        at io.kd.figgycity50.mpos.mposchecker.MainActivity$DownloadWebpageTask.doInBackground(MainActivity.java:77)
        at io.kd.figgycity50.mpos.mposchecker.MainActivity$DownloadWebpageTask.doInBackground(MainActivity.java:64)
        at android.os.AsyncTask$2.call(AsyncTask.java:288)
        at java.util.concurrent.FutureTask.run(FutureTask.java:237)
            
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
            at java.lang.Thread.run(Thread.java:841)
 Caused by: java.io.EOFException: End of input at line 1 column 501
        at com.google.gson.stream.JsonReader.nextNonWhitespace(JsonReader.java:1377)
        at com.google.gson.stream.JsonReader.doPeek(JsonReader.java:471)
        at com.google.gson.stream.JsonReader.skipValue(JsonReader.java:1209)
        at com.google.gson.internal.bind.ReflectiveTypeAdapterFactory$Adapter.read(ReflectiveTypeAdapterFactory.java:170)
        at com.google.gson.Gson.fromJson(Gson.java:803)
            at com.google.gson.Gson.fromJson(Gson.java:768)
            at com.google.gson.Gson.fromJson(Gson.java:717)
            at com.google.gson.Gson.fromJson(Gson.java:689)
            at io.kd.figgycity50.mpos.mposchecker.MainActivity$DownloadWebpageTask.doInBackground(MainActivity.java:77)
            at io.kd.figgycity50.mpos.mposchecker.MainActivity$DownloadWebpageTask.doInBackground(MainActivity.java:64)
            at android.os.AsyncTask$2.call(AsyncTask.java:288)
            at java.util.concurrent.FutureTask.run(FutureTask.java:237)
            at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
            at java.lang.Thread.run(Thread.java:841)

这是获取和解析JSON的代码：

private class DownloadWebpageTask extends AsyncTask<String, Void, String> {
        @Override
        protected String doInBackground(String... urls) {

            // params comes from the execute() call: params[0] is the url.
            String resp = null;
            try {
                resp =  downloadUrl(urls[0]);
            } catch (IOException e) {
                resp = "{\"getdashboarddata\":{\"data\":{\"personal\":{\"hashrate\":0},\"pool\":{\"info\":{\"name\":\"SET POOL IN SETTINGS\",\"currency\":\"???\"},\"hashrate\":0,\"difficulty\":0},\"network\":{\"hashrate\":0,\"difficulty\":0}}}}";
            }
            Gson gson = new Gson();
            Log.d("INFO", resp);
            MPOSDashStruct data = gson.fromJson(resp, MPOSDashStruct.class);
            TextView t = (TextView)findViewById(R.id.poolName);
            TextView t2 = (TextView)findViewById(R.id.khashMe);
            TextView t3 = (TextView)findViewById(R.id.khashPool);
            TextView t4 = (TextView)findViewById(R.id.khashNet);
            t.setText(data.getName());
            t2.setText(data.getMyHash());
            t3.setText(data.getPoolHash());
            t4.setText(data.getNetHash());
            return "Hello World. If you see this, you probably hack. Get out.";
        }

        private String downloadUrl(String myurl) throws IOException {
            InputStream is = null;
            // Only display the first 500 characters of the retrieved
            // web page content.
            int len = 500;

            try {
                URL url = new URL(myurl);
                HttpURLConnection conn = (HttpURLConnection) url.openConnection();
                conn.setReadTimeout(10000 /* milliseconds */);
                conn.setConnectTimeout(15000 /* milliseconds */);
                conn.setRequestMethod("GET");
                conn.setDoInput(true);
                // Starts the query
                conn.connect();
                int response = conn.getResponseCode();
                is = conn.getInputStream();

                // Convert the InputStream into a string
                String contentAsString = readIt(is, len);
                return contentAsString;

                // Makes sure that the InputStream is closed after the app is
                // finished using it.
            } finally {
                if (is != null) {
                    is.close();
                }
            }
        }

        public String readIt(InputStream stream, int len) throws IOException, UnsupportedEncodingException {
            Reader reader = null;
            reader = new InputStreamReader(stream, "UTF-8");
            char[] buffer = new char[len];
            reader.read(buffer);
            return new String(buffer);
        }
    }
}

这是MPOSDashStruct类：

package io.kd.figgycity50.mpos.mposchecker;

import com.google.gson.annotations.SerializedName;

/**
 * Created by George on 25/05/2014.
 */
public class MPOSDashStruct {
    public static class getdashboarddata {
        public static class data {
            public static class personal {
                public static int hashrate;
            }
            public static class pool {
                public static int hashrate;
                public static int difficulty;
                public static class info {
                    @SerializedName("name")
                    public static String poolName;
                    public static String currency;
                }
            }
            public static class network {
                public static int hashrate;
                public static int difficulty;
            }
        }
    }
    public String getName() {
        return getdashboarddata.data.pool.info.poolName;
    }

    public String getCurrency() {
        return getdashboarddata.data.pool.info.currency;
    }

    public int getPoolHash() {
        return getdashboarddata.data.pool.hashrate;
    }

    public int getPoolDiff() {
        return getdashboarddata.data.pool.difficulty;
    }

    public int getMyHash() {
        return getdashboarddata.data.personal.hashrate;
    }

    public int getNetHash() {
        return getdashboarddata.data.network.hashrate;
    }
}

该代码看起来不错，并且Android Studio没有错误。

编辑2：contentAsString输出

05-25 17:30:12.976  29974-29988/io.kd.figgycity50.mpos.mposchecker D/INFO﹕ {"getdashboarddata":{"version":"1.0.0","runtime":632.7919960022,"data":{"raw":{"personal":{"hashrate":0},"pool":{"hashrate":1675289},"network":{"hashrate":38541151.201,"esttimeperblock":61.161346587453,"nextdifficulty":538.41366248,"blocksuntildiffchange":1}},"personal":{"hashrate":0,"sharerate":"0.0000","sharedifficulty":0,"shares":{"valid":0,"invalid":0,"invalid_percent":0,"unpaid":0},"estimates":{"block":0,"fee":0,"donation":0,"payout":0}},"pool":{"info":{"name":"RAPIDHASH","currency":"DOGE"}

使用Log.d（“ INFO”，contentAsString）

编辑：使用getContentLength之后，新的logcat是这样的：

05-25 17:50:19.203    5143-5157/io.kd.figgycity50.mpos.mposchecker W/dalvikvm﹕ threadid=11: thread exiting with uncaught exception (group=0x41bd4ba8)
05-25 17:50:19.203    5143-5157/io.kd.figgycity50.mpos.mposchecker E/AndroidRuntime﹕ FATAL EXCEPTION: AsyncTask #1
    Process: io.kd.figgycity50.mpos.mposchecker, PID: 5143
    java.lang.RuntimeException: An error occured while executing doInBackground()
            at android.os.AsyncTask$3.done(AsyncTask.java:300)
            at java.util.concurrent.FutureTask.finishCompletion(FutureTask.java:355)
            at java.util.concurrent.FutureTask.setException(FutureTask.java:222)
            at java.util.concurrent.FutureTask.run(FutureTask.java:242)
            at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
            at java.lang.Thread.run(Thread.java:841)
     Caused by: java.lang.NegativeArraySizeException: -1
            at io.kd.figgycity50.mpos.mposchecker.MainActivity$DownloadWebpageTask.readIt(MainActivity.java:120)
            at io.kd.figgycity50.mpos.mposchecker.MainActivity$DownloadWebpageTask.downloadUrl(MainActivity.java:104)
            at io.kd.figgycity50.mpos.mposchecker.MainActivity$DownloadWebpageTask.doInBackground(MainActivity.java:71)
            at io.kd.figgycity50.mpos.mposchecker.MainActivity$DownloadWebpageTask.doInBackground(MainActivity.java:64)
            at android.os.AsyncTask$2.call(AsyncTask.java:288)
            at java.util.concurrent.FutureTask.run(FutureTask.java:237)
            at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:231)
            at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1112)
            at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:587)
            at java.lang.Thread.run(Thread.java:841)

指向我的代码的这一行：

public String readIt(InputStream stream, int len) throws IOException, UnsupportedEncodingException {
            Reader reader = null;
            reader = new InputStreamReader(stream, "UTF-8");
            char[] buffer = new char[len]; //this line, others added so you can understand
            reader.read(buffer);
            return new String(buffer);
        }

编辑3：指导Gson处理读取器工作正常，但再次出现新的错误。 Logcat：

05-26 09:17:52.459  11810-11810/io.kd.figgycity50.mpos.mposchecker E/AndroidRuntime﹕ FATAL EXCEPTION: main
    Process: io.kd.figgycity50.mpos.mposchecker, PID: 11810
    java.lang.RuntimeException: Unable to start activity ComponentInfo{io.kd.figgycity50.mpos.mposchecker/io.kd.figgycity50.mpos.mposchecker.MainActivity}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2195)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at io.kd.figgycity50.mpos.mposchecker.MainActivity.onCreate(MainActivity.java:49)
            at android.app.Activity.performCreate(Activity.java:5231)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1087)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2159)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2245)
            at android.app.ActivityThread.access$800(ActivityThread.java:135)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1196)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:136)
            at android.app.ActivityThread.main(ActivityThread.java:5017)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:515)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:779)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:595)
            at dalvik.system.NativeStart.main(Native Method)

指向：

protected void onCreate(Bundle savedInstanceState){
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        SharedPreferences sharedPref = PreferenceManager.getDefaultSharedPreferences(this);
        String prefPool = sharedPref.getString("pref_pool", "https://doge.rapidhash.net/");
        String prefKey = sharedPref.getString("pref_key", "XXXX");
        new DownloadWebpageTask().execute(prefPool + "index.php?page=api&action=getdashboarddata&api_key=" + prefKey);
        TextView t = (TextView)findViewById(R.id.poolName); // this line
        TextView t2 = (TextView)findViewById(R.id.khashMe);
        TextView t3 = (TextView)findViewById(R.id.khashPool);
        TextView t4 = (TextView)findViewById(R.id.khashNet);
        t.setText(dashStruct.getName());
        t2.setText(dashStruct.getMyHash());
        t3.setText(dashStruct.getPoolHash());
        t4.setText(dashStruct.getNetHash());
    }

最佳答案

在上面的Edit 3中，以下行似乎抛出了NullPointerException：

t.setText(dashStruct.getName());

我可以告诉您将dashStruct声明为在AsyncTask DownloadWebpageTask中初始化的类级别变量。

通过设计，AsyncTask将在主线程上执行（确切地说，是AsyncTask＃doInBackground（T）方法）。如果在主线程执行DownloadWebpageTask时dashStruct尚未完成初始化t.setText(dashStruct.getName());，则将引发NPE-dashStruct为null。

要克服此异常，请覆盖onPostExecute()中的DownloadWebpageTask并将以下代码移至该异常（将其从onCreate(Bundle)删除）：

@Override
protected void onPostExecute(String result) {

    if (dashStruct != null) {
        t.setText(dashStruct.getName());
        t2.setText(dashStruct.getMyHash());
        t3.setText(dashStruct.getPoolHash());
        t4.setText(dashStruct.getNetHash());
    } else {
        // Deal with dashStruct being null
    }
}

我注意到在您的原始帖子中，您正在从DownloadWebpageTask#doInBackground(String...)更新UI（设置textview文本）。当从主线程处理了IllegalStateException时，这将抛出一个doInBackground()，这是唯一允许触摸您的UI的线程。 onPostExecute()在主线程上处理。这就是您的UI逻辑应该去的地方。