java - Java - 阻止 GSON 创建额外的线程
问题描述
我正在用 Java 编写一些小代码片段,以便在移动应用程序后端服务器上运行。我使用的服务器有一个线程的限制,所以我写的代码需要基本上是同步和单线程的。
我正在使用 gson 解析从第三方 API 检索到的 JSON,一些示例代码如下:
public class JSONWorker {
public double getJSONFromURL(String sURL){
JsonParser jp = new JsonParser(); //from gson
JsonElement root = null;
// Connect to the URL using java's native library
URL url = null;
try {
url = new URL(sURL);
} catch (MalformedURLException e) {
e.printStackTrace();
}
URLConnection request = null;
try {
request = url.openConnection();
} catch (IOException e) {
e.printStackTrace();
}
try {
request.connect();
} catch (IOException e) {
e.printStackTrace();
}
try {
root = jp.parse(new InputStreamReader((InputStream) request.getContent()));
} catch (IOException e) {
e.printStackTrace();
}
JsonObject rootobj = root.getAsJsonObject();
String price = rootobj.get("lastPrice").getAsString();
return Double.parseDouble(price);
}
}
返回的错误表明我无权创建额外的线程并指向此特定行作为问题:
root = jp.parse(new InputStreamReader((InputStream) request.getContent()));
gson 中的 JSON 解析器应该创建一个额外的线程是否正确?这可能与它在远程服务器上运行的事实有关吗?有没有办法强制 gson 或特别是解析器同步/单线程?
编辑:完整的错误输出
[ERROR] You have no permission to create thread in CodeRunner secure group.
java.lang.reflect.InvocationTargetException: null
at sun.reflect.GeneratedMethodAccessor20.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.backendless.coderunner.runtime.task.TimerInvocationTask.runImpl(TimerInvocationTask.java:52)
at com.backendless.coderunner.runtime.executor.ExtendedRunnable.run(ExtendedRunnable.java:39)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.security.AccessControlException: You have no permission to create thread in CodeRunner secure group.
at com.backendless.coderunner.runtime.security.CodeRunnerSecurityManager.checkAccess(CodeRunnerSecurityManager.java:48)
at java.lang.ThreadGroup.checkAccess(ThreadGroup.java:315)
at java.lang.ThreadGroup.getParent(ThreadGroup.java:167)
at sun.net.www.http.KeepAliveCache$1.run(KeepAliveCache.java:102)
at sun.net.www.http.KeepAliveCache$1.run(KeepAliveCache.java:96)
at java.security.AccessController.doPrivileged(Native Method)
at sun.net.www.http.KeepAliveCache.put(KeepAliveCache.java:95)
at sun.net.www.protocol.https.HttpsClient.putInKeepAliveCache(HttpsClient.java:659)
at sun.net.www.http.HttpClient.finished(HttpClient.java:395)
at sun.net.www.http.KeepAliveStream.close(KeepAliveStream.java:97)
at sun.net.www.MeteredStream.justRead(MeteredStream.java:93)
at sun.net.www.MeteredStream.read(MeteredStream.java:135)
at java.io.FilterInputStream.read(FilterInputStream.java:133)
at sun.net.www.protocol.http.HttpURLConnection$HttpInputStream.read(HttpURLConnection.java:3393)
at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:284)
at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:326)
at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:178)
at java.io.InputStreamReader.read(InputStreamReader.java:184)
at com.google.gson.stream.JsonReader.fillBuffer(JsonReader.java:1295)
at com.google.gson.stream.JsonReader.nextNonWhitespace(JsonReader.java:1333)
at com.google.gson.stream.JsonReader.consumeNonExecutePrefix(JsonReader.java:1576)
at com.google.gson.stream.JsonReader.doPeek(JsonReader.java:534)
at com.google.gson.stream.JsonReader.peek(JsonReader.java:425)
at com.google.gson.internal.Streams.parse(Streams.java:46)
at com.google.gson.JsonParser.parse(JsonParser.java:84)
at com.google.gson.JsonParser.parse(JsonParser.java:59)
at com.myApp.timers.PriceGetterTimer.execute(PriceGetterTimer.java:100)
... 6 common frames omitted
干杯,米奇
解决方案
线程是由内置的KeepAliveCache
.
您可以指定请求标头Connection
的值为Close
或将系统属性设置http.keepAlive
为这样的值false
(在您实际打开连接之前):
System.setProperty("http.keepAlive", "false");
更多信息可以在这里找到
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