有时我的Servlet会以此异常结束：
WARNING: StandardWrapperValve[HeartBeatServlet]: PWC1406: Servlet.service() for servlet HeartBeatServlet threw exception
java.lang.IllegalStateException: Not Suspended
at com.sun.grizzly.tcp.Response.resume(Response.java:768)
at org.apache.catalina.connector.Request.asyncComplete(Request.java:3993)
at org.apache.catalina.connector.AsyncContextImpl.complete(AsyncContextImpl.java:242)
at com.northcane.talkeen.HeartBeatServlet.doPost(HeartBeatServlet.java:47)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:688)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:770)
at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1550)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:161)
at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:331)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:231)
at com.sun.enterprise.v3.services.impl.ContainerMapper$AdapterCallable.call(ContainerMapper.java:317)
at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:195)
at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:860)
at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:757)
at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1056)
at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:229)
at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
at java.lang.Thread.run(Thread.java:722)
这是我的Servlet的来源。它唯一能做的就是处理来自javascript客户端的长轮询请求，并将POST收到的消息发送给所有人：
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.List;
import javax.servlet.AsyncContext;
import javax.servlet.ServletResponse;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet(name = "HeartBeatServlet", urlPatterns = {"/HeartBeatServlet"}, asyncSupported = true)
public class HeartBeatServlet extends HttpServlet {
private List<AsyncContext> asyncContextList = new LinkedList<>();
@Override
public void doGet(HttpServletRequest request, HttpServletResponse response) {
AsyncContext asyncContext = request.startAsync(request, response);
asyncContext.setTimeout(30000);
asyncContextList.add(asyncContext);
}
@Override
public void doPost(HttpServletRequest request, HttpServletResponse response) {
String test = request.getParameter("message");
List<AsyncContext> asyncContexts = new ArrayList<>(asyncContextList);
asyncContextList.clear();
for (AsyncContext asyncContext : asyncContexts) {
ServletResponse res = asyncContext.getResponse();
res.setContentType("text/html");
try {
PrintWriter out = asyncContext.getResponse().getWriter();
out.println(test + " <br />");
out.flush();
asyncContext.complete();
} catch (IOException e) {
e.printStackTrace();
}
}
}
}