Question

我有一个java servlet，它设置一个会话变量并调用一个启动一个线程类。我的实现是一个跟随

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我有一个执行长过程的线程类，如下所示;

@WebServlet("/ExportLogs")
public class ExportLogs extends HttpServlet
{
    public void doGet(HttpServletRequest request , HttpServletResponse response) throws ServletException,IOException
    {

        Integer completePercent = new Integer(10);

        request.getSession().setAttribute("CompletionStatus" , completePercent);

        LogExportingProcess export = new LogExportingProcess();
        export.start();
    }
}

现在我想在LogExportingProcess类中更改completePercent值的值。我怎样才能实现它。

Answer 1

您必须在创建Session

时传递LogExportingProcess对象

class LogExportingProcess extends Thread 
{
    private HttpSession session;

    public LogExportingProcess(HttpSession session) {
       this.session = session;
    }

    public void run()
    {
        session.setAttribute("CompletionStatus" , completePercent);
    }   
}

并在ExportLogs类

中进行了一次更改

LogExportingProcess export = new LogExportingProcess(request.getSession());

Answer 2

整数不可变。 AtomicInteger将是一个很好的替代品。

@WebServlet("/ExportLogs")
public class ExportLogs extends HttpServlet
{
    public void doGet( final HttpServletRequest request , final HttpServletResponse response ) throws ServletException,IOException
    {
        final AtomicInteger completePercent = new AtomicInteger(10);

        request.getSession().setAttribute("CompletionStatus" , completePercent);

        final LogExportingProcess export = new LogExportingProcess( completePercent );
        export.start();
    }
}

class LogExportingProcess extends Thread 
{
    final AtomicInteger completePercent;

    public LogExportingProcess( final AtomicInteger completePercent ) 
    {
       this.completePercent = completePercent;
    }

    public void run()
    {
        completePercent.set( 80 ); //80% complete, substitute with real code
    }   
}

根据Yogesh Badke的建议，这是优先考虑持有对HttpSession对象的引用，因为HttpSession可以在超时时正常进行垃圾收集，而AtomicInteger只通过共享百分比而不是整个会话信息来增加封装。

如何在任意java类中更改会话变量的值

2 个答案: