JAVA尝试使用简单调度程序（计时器、TimerTask）在JSP页面上打印后获取IOException。需要帮助吗

我正在尝试使用Timer和TimerTask类创建简单的调度器。请参阅下面的代码，在任务内部，我只想在页面上打印“Hello，World！”，但它抛出IOException:Stream closed。请帮忙

JSP页面代码：

<% Test t = new Test(out);%>

LpdbTask代码：

public class LpdbTask extends TimerTask{
    public JspWriter out;
    public void run(){
        try {
            out.println("Hello, World!");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

错误：

java.io.IOException: Stream closed
    at org.apache.jasper.runtime.JspWriterImpl.ensureOpen(JspWriterImpl.java:204)
    at org.apache.jasper.runtime.JspWriterImpl.write(JspWriterImpl.java:312)
    at org.apache.jasper.runtime.JspWriterImpl.write(JspWriterImpl.java:342)
    at org.apache.jasper.runtime.JspWriterImpl.print(JspWriterImpl.java:468)
    at org.apache.jasper.runtime.JspWriterImpl.println(JspWriterImpl.java:576)
    at scheduler.LpdbTask.run(LpdbTask.java:14)
    at java.util.TimerThread.mainLoop(Unknown Source)
    at java.util.TimerThread.run(Unknown Source)

---

JSP的Java代码在用户看到您的页面之前运行。当

定时器

触发时，JSP已经被发送到浏览器并呈现；由于不再需要，该流实际上已关闭。这是不可能做到的

如果您希望在用户浏览器中的页面上发生与时间相关的事情，那么您必须使用Javascript、Flash或Java小程序来完成；所有这些都在桌面上运行，而JSP则在服务器上运行

java.io.IOException: Stream closed
    at org.apache.jasper.runtime.JspWriterImpl.ensureOpen(JspWriterImpl.java:204)
    at org.apache.jasper.runtime.JspWriterImpl.write(JspWriterImpl.java:312)
    at org.apache.jasper.runtime.JspWriterImpl.write(JspWriterImpl.java:342)
    at org.apache.jasper.runtime.JspWriterImpl.print(JspWriterImpl.java:468)
    at org.apache.jasper.runtime.JspWriterImpl.println(JspWriterImpl.java:576)
    at scheduler.LpdbTask.run(LpdbTask.java:14)
    at java.util.TimerThread.mainLoop(Unknown Source)
    at java.util.TimerThread.run(Unknown Source)