/**
* Copyright (c) 2005-2012 https://github.com/zhangkaitao
*
* Licensed under the Apache License, Version 2.0 (the "License");
*/
package com.sishuok.chapter3.web.servlet.listener;
import javax.servlet.AsyncContext;
import javax.servlet.AsyncEvent;
import javax.servlet.AsyncListener;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.OutputStream;
/**
* <p>User: Zhang Kaitao
* <p>Date: 13-7-18 上午7:19
* <p>Version: 1.0
*/
@WebServlet(name = "listenerServlet3", urlPatterns = "/listener3", asyncSupported = true)
public class ListenerServlet3 extends HttpServlet {
@Override
protected void doGet(final HttpServletRequest req, final HttpServletResponse resp) throws ServletException, IOException {
final AsyncContext asyncContext = req.startAsync();
asyncContext.setTimeout(10 * 1000);
asyncContext.addListener(new AsyncListener() {
@Override
public void onComplete(final AsyncEvent event) throws IOException {
System.out.println("=====async complete");
}
@Override
public void onTimeout(final AsyncEvent event) throws IOException {
System.out.println("=====async timeout");
asyncContext.complete(); //需要调用下complete 否则如jetty默认每2秒重新调度一次当前方法
}
@Override
public void onError(final AsyncEvent event) throws IOException {
System.out.println("=====async error");
//如果有队列请从队列中移除
}
@Override
public void onStartAsync(final AsyncEvent event) throws IOException {
System.out.println("=====start new async");
}
});
/**
* 以jetty为例
*
* 1、当响应流关闭了，如果还写指定长度个字节，org.eclipse.jetty.server.HttpOutput会抛出EofException
*
* org.eclipse.jetty.server.HttpOutput会
* if (isClosed())
* throw new EofException("Closed");
*
* 2、org.eclipse.jetty.server.HttpChannel会调用org.eclipse.jetty.server.HttpChannelState的error方法设置
* _event.setThrowable(th);
*
* 3、当调用asyncContext.complete时，最终会调用HttpChannelState的completed方法：其内部
* 如果有异常调用onError 否则onComplete
* if (event!=null && event.getThrowable()!=null)
* {
* event.getSuppliedRequest().setAttribute(RequestDispatcher.ERROR_EXCEPTION,event.getThrowable());
* event.getSuppliedRequest().setAttribute(RequestDispatcher.ERROR_MESSAGE,event.getThrowable().getMessage());
* listener.onError(event);
* }
* else
* listener.onComplete(event);
*
* 4、也就是说 只要流程正确 不会有这个问题
*/
final OutputStream os = resp.getOutputStream();
os.write(new byte[] {1}, 0, 1);
os.close();
os.write(new byte[] {1}, 0, 1);
}
}