public class LoadClassServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;
    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
        doPost(req, resp);
    }
    @Override
    protected void doPost(HttpServletRequest request, HttpServletResponse response)
            
 
throws ServletException, IOException {

        System.out.println(" Start Servlet " + DateUtil.getDefaultFormatDate(System.currentTimeMillis()));
        System.out.println(" doPost() Thread Name : " + Thread.currentThread().getName());
        
        System.out.println( " In doPost " + request);
        System.out.println( 
 
" In doPost " + response);

        request.setAttribute("org.apache.catalina.ASYNC_SUPPORTED", true);
        //  開啟非同步週期
        AsyncContext asyncContext = request.startAsync();
        asyncContext.setTimeout(10*1000);
        asyncContext.start(new Runnable() {
            
            @Override
            
 
public void run() {
                try {
                    System.out.println(" run() Thread Name : " + Thread.currentThread().getName());
                    //  模擬啟用執行緒非同步遞送訊號, 一般來說是一些耗時的操作
                    System.out.println(" Before Sleep " + DateUtil.getDefaultFormatDate(System.currentTimeMillis()));
                    Thread.sleep(5 * 1000);
                    System.out.println(" After Sleep " + DateUtil.getDefaultFormatDate(System.currentTimeMillis()));
                    asyncContext.complete();
                    System.out.println(" After complete() " + DateUtil.getDefaultFormatDate(System.currentTimeMillis()));
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        });
        System.out.println( " In AsyncContext " + asyncContext.getRequest() );
        System.out.println( " In AsyncContext " + asyncContext.getResponse() );
        
        asyncContext.addListener( new AsyncListener() {
            @Override
            public void onTimeout(AsyncEvent event) throws IOException {
                //  /////////////////////////////////////
                //  這個方法內一般會寫一些關於超時的邏輯
                //  假設10s還沒有收到返回的訊號, 就將錯誤訊息
                //  在這裡通過response物件返回給客戶端
                //  /////////////////////////////////////
                System.out.println(" onTimeout() " + DateUtil.getDefaultFormatDate(System.currentTimeMillis()));
                
                event.getSuppliedResponse().getWriter().println(" timeout ");
            }
            
            @Override
            public void onStartAsync(AsyncEvent event) throws IOException {
                System.out.println(" onStartAsync() ");
            }
            
            @Override
            public void onError(AsyncEvent event) throws IOException {
                System.out.println(" onError() ");
            }
            
            @Override
            public void onComplete(AsyncEvent event) throws IOException {

                //  ///////////////////////////
                //  這個方法無論怎樣都會被呼叫
                //  不管是手動呼叫complete()方法
                //  還是超時, 這個方法都會被執行
                //  ///////////////////////////
                
                System.out.println(" onComplete() " + DateUtil.getDefaultFormatDate(System.currentTimeMillis()));
                System.out.println(" onComplete() Thread Name : " + Thread.currentThread().getName());
                System.out.println( " In AsyncEvent "+event.getSuppliedRequest() );
                System.out.println( " In AsyncEvent "+event.getSuppliedResponse() );
                
                event.getSuppliedResponse().getWriter().println(" complete ");
            }
        } );
        System.out.println( " End of Servlet " + DateUtil.getDefaultFormatDate(System.currentTimeMillis()));
    }
}