我是通过GET请求从网上获取JSON数据。代码如下，即使问题似乎是“概念性的”。
/**
* Make an HTTP request to the given URL and return a String as the response.
*/
public static String makeHttpRequest(URL url) throws IOException {
String jsonResponse = "";
//Check that url is not null
if(url == null){
return jsonResponse;
}
HttpURLConnection urlConnection = null;
InputStream inputStream = null;
try {
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setReadTimeout(10000 /* milliseconds */);
urlConnection.setConnectTimeout(15000 /* milliseconds */);
urlConnection.connect();
//If the request was successfull (code 200)
//then read the imput string and parse the response
if(urlConnection.getResponseCode() == 200) {
inputStream = urlConnection.getInputStream();
jsonResponse = readFromStream(inputStream);
}
else {
Log.e(LOG_TAG_MAIN, "Error Response code" + urlConnection.getResponseCode());
}
} catch (IOException e) {
Log.e(LOG_TAG_MAIN, "Problem the JSON results", e);
} finally {
if (urlConnection != null) {
urlConnection.disconnect();
}
if (inputStream != null) {
// Closing the input stream could throw an IOException, which is why
// the makeHttpRequest(URL url) method signature specifies than an IOException
// could be thrown.
inputStream.close();
}
}
return jsonResponse;
}
//$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$$
/**
* Convert the {@link InputStream} into a String which contains the
* whole JSON response from the server.
*/
public static String readFromStream(InputStream inputStream) throws IOException {
StringBuilder output = new StringBuilder();
if (inputStream != null) {
InputStreamReader inputStreamReader = new InputStreamReader(inputStream, Charset.forName("UTF-8"));
BufferedReader reader = new BufferedReader(inputStreamReader);
String line = reader.readLine();
while (line != null) {
output.append(line);
line = reader.readLine();
}
}
return output.toString();
}
确实以下代码工作了好几个月，但突然开始抛出：
E/com.example.android.abcfolio.MainActivity: Problem the JSON results
java.net.SocketTimeoutException: timeout
at com.android.okhttp.okio.Okio$3.newTimeoutException(Okio.java:207)
at com.android.okhttp.okio.AsyncTimeout.exit(AsyncTimeout.java:250)
at com.android.okhttp.okio.AsyncTimeout$2.read(AsyncTimeout.java:217)
at com.android.okhttp.okio.RealBufferedSource.request(RealBufferedSource.java:71)
at com.android.okhttp.okio.RealBufferedSource.require(RealBufferedSource.java:64)
at com.android.okhttp.okio.RealBufferedSource.readHexadecimalUnsignedLong(RealBufferedSource.java:270)
at com.android.okhttp.internal.http.HttpConnection$ChunkedSource.readChunkSize(HttpConnection.java:479)
at com.android.okhttp.internal.http.HttpConnection$ChunkedSource.read(HttpConnection.java:460)
at com.android.okhttp.okio.RealBufferedSource.read(RealBufferedSource.java:50)
at com.android.okhttp.okio.RealBufferedSource.exhausted(RealBufferedSource.java:60)
at com.android.okhttp.okio.InflaterSource.refill(InflaterSource.java:101)
at com.android.okhttp.okio.InflaterSource.read(InflaterSource.java:62)
at com.android.okhttp.okio.GzipSource.read(GzipSource.java:80)
at com.android.okhttp.okio.RealBufferedSource$1.read(RealBufferedSource.java:349)
at java.io.InputStreamReader.read(InputStreamReader.java:233)
at java.io.BufferedReader.fillBuf(BufferedReader.java:145)
at java.io.BufferedReader.readLine(BufferedReader.java:397)
at com.example.android.abcfolio.utils.NetworkCommonUtils.readFromStream(NetworkCommonUtils.java:102)
at com.example.android.abcfolio.utils.NetworkCommonUtils.makeHttpRequest(NetworkCommonUtils.java:68)
at com.example.android.abcfolio.utils.NetworkCoinMarketCapUtils.fetchCoinMarketCapData(NetworkCoinMarketCapUtils.java:44)
at com.example.android.abcfolio.sync.CoinsSyncTask.syncCoins(CoinsSyncTask.java:65)
at com.example.android.abcfolio.sync.CoinsFirebaseJobService$1.doInBackground(CoinsFirebaseJobService.java:64)
at com.example.android.abcfolio.sync.CoinsFirebaseJobService$1.doInBackground(CoinsFirebaseJobService.java:53)
at android.os.AsyncTask$2.call(AsyncTask.java:295)
at java.util.concurrent.FutureTask.run(FutureTask.java:237)
at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:234)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1113)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:588)
at java.lang.Thread.run(Thread.java:818)
因为，我从未接触过这段代码，但我只在代码的其他部分添加了其他功能，我不明白发生了什么。我试图提高超时时间，但错误实际上立即出现，所以增加时间似乎没用。 我排除这是由于请求的大小，因为即使我只要求所有JSON的子集，它仍然会抱怨。
问题可能出在我正在查询的网站上吗？也许他们目前有太多要求？也许我用于开发的手机被禁止了太多的请求？
使用其他信息进行编辑： 1）问题是间歇性的。有时应用程序工作正常，所有数据都正确加载。 2）有时这些消息显示在LogCat中，我不确定是否相关（特别是fmradio.jar）：
03-12 12:49:36.600 16457-16457/? W/System: ClassLoader referenced unknown path: /data/app/com.example.android.abcfolio-2/lib/arm64
03-12 12:49:36.603 16457-16457/? I/InstantRun: Instant Run Runtime started. Android package is com.example.android.abcfolio, real application class is null.
[ 03-12 12:49:36.607 16457:16457 W/ ]
Unable to open '/system/framework/qcom.fmradio.jar': No such file or directory
03-12 12:49:36.607 16457-16457/? W/art: Failed to open zip archive '/system/framework/qcom.fmradio.jar': I/O Error
[ 03-12 12:49:36.607 16457:16457 W/ ]
Unable to open '/system/framework/oem-services.jar': No such file or directory
03-12 12:49:36.607 16457-16457/? W/art: Failed to open zip archive '/system/framework/oem-services.jar': I/O Error
03-12 12:49:37.149 16457-16470/? I/art: Debugger is no longer active
03-12 12:49:39.030 16457-16457/com.example.android.abcfolio W/System: ClassLoader referenced unknown path: /data/app/com.example.android.abcfolio-2/lib/arm64
03-12 12:49:43.962 16457-16457/com.example.android.abcfolio W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
3）还有其他多个警告，如
W/PathParser: Points are too far apart 4.000000000000003
这些应归功于ConstraintLayout。它可能是使用太多内存来在主线程上执行图形工作，这会在http请求中变成错误吗？ （我似乎不太可能，但它可以解释为什么现在这个问题出现了，在我用ConstraintLayout插入了许多视图之后）
编辑2： 4）在应用程序中，我以两种不同的方式获取数据：一个使用简单的Loader扩展AsyncTaskLoader，另一个使用Firebase作业服务。是第二个给出问题的，即使它们获取相同的API并使用上面写的两种方法。
编辑3： 5）我现在确定问题不是由于最近在代码中所做的更改，因为即使是较旧的应用程序备份版本也会以相同的方式运行。 6）现在它扔了这个：
Problem parsing the JSON results
java.io.EOFException
at com.android.okhttp.okio.RealBufferedSource.require(RealBufferedSource.java:64)
at com.android.okhttp.okio.RealBufferedSource.readHexadecimalUnsignedLong(RealBufferedSource.java:270)
at com.android.okhttp.internal.http.HttpConnection$ChunkedSource.readChunkSize(HttpConnection.java:479)
at com.android.okhttp.internal.http.HttpConnection$ChunkedSource.read(HttpConnection.java:460)
at com.android.okhttp.okio.RealBufferedSource.read(RealBufferedSource.java:50)
at com.android.okhttp.okio.RealBufferedSource.exhausted(RealBufferedSource.java:60)
at com.android.okhttp.okio.InflaterSource.refill(InflaterSource.java:101)
at com.android.okhttp.okio.InflaterSource.read(InflaterSource.java:62)
at com.android.okhttp.okio.GzipSource.read(GzipSource.java:80)
at com.android.okhttp.okio.RealBufferedSource$1.read(RealBufferedSource.java:349)
at java.io.InputStreamReader.read(InputStreamReader.java:233)
at java.io.BufferedReader.fillBuf(BufferedReader.java:145)
at java.io.BufferedReader.readLine(BufferedReader.java:397)
at com.example.android.abcfolio.utils.NetworkCommonUtils.readFromStream(NetworkCommonUtils.java:106)
at com.example.android.abcfolio.utils.NetworkCommonUtils.makeHttpRequest(NetworkCommonUtils.java:72)
at com.example.android.abcfolio.utils.NetworkCoinMarketCapUtils.fetchCoinMarketCapData(NetworkCoinMarketCapUtils.java:44)
at com.example.android.abcfolio.sync.CoinsSyncTask.syncCoins(CoinsSyncTask.java:89)
at com.example.android.abcfolio.sync.CoinsSyncIntentService.onHandleIntent(CoinsSyncIntentService.java:33)
at android.app.IntentService$ServiceHandler.handleMessage(IntentService.java:66)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:148)
at android.os.HandlerThread.run(HandlerThread.java:61)
编辑4： 6）我已经记录了urlConnection.getResponseCode（）+ urlConnection.getResponseMessage（），有时候，它会返回：504Gateway Time-out，而不是成功代码200。
答案 0 :(得分：0)
当您设置超时时，服务器为您的请求提供的服务时间比您原先预期的要长。它们很短。它们应该在几分钟内，而不是几秒钟。
它与你的应用程序正在做的其他事情没有任何关系。