我有个问题：
我有一个代码，可以在DBPedia上调用不同的查询。
这是我的代码：
ResIterator resi = model.listSubjects();
while (resi.hasNext()) {
Resource subject = resi.nextResource();
QueryExecution exec1 = queryDBPedia(subject);
ResultSet results1 = ResultSetFactory.copyResults(exec1.execSelect());
if (results1.hasNext()) {
while (results1.hasNext()) {
QuerySolution qs = results1.next();
if (qs.get("resource") != null) {
//TO DO SOMETHING
}
}
}
exec1.close();
}
在我的模型中，我有100多种资源。当我在使用Netbeans和Glassfish 4.0的Web服务（带有客户端）中运行此代码时，出现此错误：
Caused by: java.net.SocketTimeoutException: Read timed out
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:152)
at java.net.SocketInputStream.read(SocketInputStream.java:122)
at org.apache.http.impl.io.AbstractSessionInputBuffer.fillBuffer(AbstractSessionInputBuffer.java:166)
at org.apache.http.impl.io.SocketInputBuffer.fillBuffer(SocketInputBuffer.java:90)
at org.apache.http.impl.io.AbstractSessionInputBuffer.readLine(AbstractSessionInputBuffer.java:281)
at org.apache.http.impl.conn.LoggingSessionInputBuffer.readLine(LoggingSessionInputBuffer.java:115)
at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:92)
at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:61)
at org.apache.http.impl.io.AbstractMessageParser.parse(AbstractMessageParser.java:254)
at org.apache.http.impl.AbstractHttpClientConnection.receiveResponseHeader(AbstractHttpClientConnection.java:289)
at org.apache.http.impl.conn.DefaultClientConnection.receiveResponseHeader(DefaultClientConnection.java:252)
at org.apache.http.impl.conn.ManagedClientConnectionImpl.receiveResponseHeader(ManagedClientConnectionImpl.java:191)
at org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse(HttpRequestExecutor.java:300)
at org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:127)
at org.apache.http.impl.client.DefaultRequestDirector.tryExecute(DefaultRequestDirector.java:715)
at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:520)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:906)
at org.apache.http.impl.client.DecompressingHttpClient.execute(DecompressingHttpClient.java:137)
at org.apache.http.impl.client.DecompressingHttpClient.execute(DecompressingHttpClient.java:118)
at org.apache.jena.riot.web.HttpOp.exec(HttpOp.java:1109)
at org.apache.jena.riot.web.HttpOp.execHttpGet(HttpOp.java:384)
at org.apache.jena.riot.web.HttpOp.execHttpGet(HttpOp.java:446)
at com.hp.hpl.jena.sparql.engine.http.HttpQuery.execGet(HttpQuery.java:346)
... 94 more
Avvertenza: javax.ejb.EJBException
at com.sun.ejb.containers.EJBContainerTransactionManager.processSystemException(EJBContainerTransactionManager.java:748)
at com.sun.ejb.containers.EJBContainerTransactionManager.completeNewTx(EJBContainerTransactionManager.java:698)
at com.sun.ejb.containers.EJBContainerTransactionManager.postInvokeTx(EJBContainerTransactionManager.java:503)
at com.sun.ejb.containers.BaseContainer.postInvokeTx(BaseContainer.java:4475)
at com.sun.ejb.containers.WebServiceInvocationHandler.invoke(WebServiceInvocationHandler.java:205)
at com.sun.proxy.$Proxy258.publishLinkedOpenData(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.glassfish.webservices.InvokerImpl.invoke(InvokerImpl.java:82)
at org.glassfish.webservices.EjbInvokerImpl.invoke(EjbInvokerImpl.java:82)
at com.sun.xml.ws.server.InvokerTube$2.invoke(InvokerTube.java:149)
at com.sun.xml.ws.server.sei.SEIInvokerTube.processRequest(SEIInvokerTube.java:88)
at com.sun.xml.ws.api.pipe.Fiber.__doRun(Fiber.java:1136)
at com.sun.xml.ws.api.pipe.Fiber._doRun(Fiber.java:1050)
at com.sun.xml.ws.api.pipe.Fiber.doRun(Fiber.java:1019)
at com.sun.xml.ws.api.pipe.Fiber.runSync(Fiber.java:877)
at com.sun.xml.ws.api.pipe.helper.AbstractTubeImpl.process(AbstractTubeImpl.java:136)
at org.glassfish.webservices.MonitoringPipe.process(MonitoringPipe.java:142)
at com.sun.xml.ws.api.pipe.helper.PipeAdapter.processRequest(PipeAdapter.java:119)
at com.sun.xml.ws.api.pipe.Fiber.__doRun(Fiber.java:1136)
at com.sun.xml.ws.api.pipe.Fiber._doRun(Fiber.java:1050)
at com.sun.xml.ws.api.pipe.Fiber.doRun(Fiber.java:1019)
at com.sun.xml.ws.api.pipe.Fiber.runSync(Fiber.java:877)
at com.sun.xml.ws.api.pipe.helper.AbstractTubeImpl.process(AbstractTubeImpl.java:136)
at com.sun.enterprise.security.webservices.CommonServerSecurityPipe.processRequest(CommonServerSecurityPipe.java:210)
at com.sun.enterprise.security.webservices.CommonServerSecurityPipe.process(CommonServerSecurityPipe.java:142)
at com.sun.xml.ws.api.pipe.helper.PipeAdapter.processRequest(PipeAdapter.java:119)
at com.sun.xml.ws.api.pipe.Fiber.__doRun(Fiber.java:1136)
at com.sun.xml.ws.api.pipe.Fiber._doRun(Fiber.java:1050)
at com.sun.xml.ws.api.pipe.Fiber.doRun(Fiber.java:1019)
at com.sun.xml.ws.api.pipe.Fiber.runSync(Fiber.java:877)
at com.sun.xml.ws.server.WSEndpointImpl$2.process(WSEndpointImpl.java:420)
at com.sun.xml.ws.transport.http.HttpAdapter$HttpToolkit.handle(HttpAdapter.java:687)
at com.sun.xml.ws.transport.http.HttpAdapter.handle(HttpAdapter.java:266)
at com.sun.xml.ws.transport.http.servlet.ServletAdapter.handle(ServletAdapter.java:169)
at org.glassfish.webservices.Ejb3MessageDispatcher.handlePost(Ejb3MessageDispatcher.java:110)
at org.glassfish.webservices.Ejb3MessageDispatcher.invoke(Ejb3MessageDispatcher.java:80)
at org.glassfish.webservices.EjbWebServiceServlet.dispatchToEjbEndpoint(EjbWebServiceServlet.java:203)
at org.glassfish.webservices.EjbWebServiceServlet.service(EjbWebServiceServlet.java:146)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
at org.glassfish.grizzly.servlet.ServletHandler.doServletService(ServletHandler.java:242)
at org.glassfish.grizzly.servlet.ServletHandler.service(ServletHandler.java:193)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:246)
at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
at java.lang.Thread.run(Thread.java:744)
Caused by: HttpException: java.net.SocketTimeoutException: Read timed out: Unexpected error making the query: java.net.SocketTimeoutException: Read timed out
at com.hp.hpl.jena.sparql.engine.http.HttpQuery.rewrap(HttpQuery.java:417)
at com.hp.hpl.jena.sparql.engine.http.HttpQuery.execGet(HttpQuery.java:358)
at com.hp.hpl.jena.sparql.engine.http.HttpQuery.exec(HttpQuery.java:295)
at com.hp.hpl.jena.sparql.engine.http.QueryEngineHTTP.execSelect(QueryEngineHTTP.java:346)
at Prova.Prova.test(Prova.java:317)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at org.glassfish.ejb.security.application.EJBSecurityManager.runMethod(EJBSecurityManager.java:1081)
at org.glassfish.ejb.security.application.EJBSecurityManager.invoke(EJBSecurityManager.java:1153)
at com.sun.ejb.containers.BaseContainer.invokeBeanMethod(BaseContainer.java:4695)
at com.sun.ejb.EjbInvocation.invokeBeanMethod(EjbInvocation.java:630)
at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:822)
at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:582)
at org.jboss.weld.ejb.AbstractEJBRequestScopeActivationInterceptor.aroundInvoke(AbstractEJBRequestScopeActivationInterceptor.java:55)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:883)
at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:822)
at com.sun.ejb.EjbInvocation.proceed(EjbInvocation.java:582)
at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.doCall(SystemInterceptorProxy.java:163)
at com.sun.ejb.containers.interceptors.SystemInterceptorProxy.aroundInvoke(SystemInterceptorProxy.java:140)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at com.sun.ejb.containers.interceptors.AroundInvokeInterceptor.intercept(InterceptorManager.java:883)
at com.sun.ejb.containers.interceptors.AroundInvokeChainImpl.invokeNext(InterceptorManager.java:822)
at com.sun.ejb.containers.interceptors.InterceptorManager.intercept(InterceptorManager.java:369)
at com.sun.ejb.containers.BaseContainer.__intercept(BaseContainer.java:4667)
at com.sun.ejb.containers.BaseContainer.intercept(BaseContainer.java:4655)
at com.sun.ejb.containers.WebServiceInvocationHandler.invoke(WebServiceInvocationHandler.java:193)
... 57 more
Caused by: java.net.SocketTimeoutException: Read timed out
at java.net.SocketInputStream.socketRead0(Native Method)
at java.net.SocketInputStream.read(SocketInputStream.java:152)
at java.net.SocketInputStream.read(SocketInputStream.java:122)
at org.apache.http.impl.io.AbstractSessionInputBuffer.fillBuffer(AbstractSessionInputBuffer.java:166)
at org.apache.http.impl.io.SocketInputBuffer.fillBuffer(SocketInputBuffer.java:90)
at org.apache.http.impl.io.AbstractSessionInputBuffer.readLine(AbstractSessionInputBuffer.java:281)
at org.apache.http.impl.conn.LoggingSessionInputBuffer.readLine(LoggingSessionInputBuffer.java:115)
at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:92)
at org.apache.http.impl.conn.DefaultHttpResponseParser.parseHead(DefaultHttpResponseParser.java:61)
at org.apache.http.impl.io.AbstractMessageParser.parse(AbstractMessageParser.java:254)
at org.apache.http.impl.AbstractHttpClientConnection.receiveResponseHeader(AbstractHttpClientConnection.java:289)
at org.apache.http.impl.conn.DefaultClientConnection.receiveResponseHeader(DefaultClientConnection.java:252)
at org.apache.http.impl.conn.ManagedClientConnectionImpl.receiveResponseHeader(ManagedClientConnectionImpl.java:191)
at org.apache.http.protocol.HttpRequestExecutor.doReceiveResponse(HttpRequestExecutor.java:300)
at org.apache.http.protocol.HttpRequestExecutor.execute(HttpRequestExecutor.java:127)
at org.apache.http.impl.client.DefaultRequestDirector.tryExecute(DefaultRequestDirector.java:715)
at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:520)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:906)
at org.apache.http.impl.client.DecompressingHttpClient.execute(DecompressingHttpClient.java:137)
at org.apache.http.impl.client.DecompressingHttpClient.execute(DecompressingHttpClient.java:118)
at org.apache.jena.riot.web.HttpOp.exec(HttpOp.java:1109)
at org.apache.jena.riot.web.HttpOp.execHttpGet(HttpOp.java:384)
at org.apache.jena.riot.web.HttpOp.execHttpGet(HttpOp.java:446)
at com.hp.hpl.jena.sparql.engine.http.HttpQuery.execGet(HttpQuery.java:346)
... 94 more
我在这条线上收到错误：
ResultSet results1 = ResultSetFactory.copyResults（exec1.execSelect（））;
我注意到在完成许多查询后会收到此错误。为什么会出现此错误？
最佳答案
当您不关闭资源时，经常会发生这种情况（我敢打赌这是您的原因）。首先，例如，您的result1没有关闭。
另一件事是，即使将exec1.close();放在方法的末尾，在//DO SOMETHING代码中也会弹出一个异常成像。在这种情况下，您的exec1是否会关闭？正确答案为否。这正是finally块设计的目的。因此，将所有与关闭资源有关的代码放在finally块中，您应该会满意。
请注意，如果您使用的是jdk 7+，也可以使用the try-with-resources Statement以更优雅的方式进行操作
希望能有所帮助