我如何更改任意 java class 中的会话变量的值

Question

我有一个 java servlet，它设置一个会话变量并调用一个启动线程 class.I 下面是一个实现

@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();
    }
}

我有一个线程 class 执行如下长过程；

class LogExportingProcess extends Thread 
{
    public void run()
    {
        //i want to change the value of the percent complete variable in here. 
    }   
}

现在我想更改 LogExportingProcess 中的 completePercent 值 class.How 我可以实现吗？

Answer 1

创建 LogExportingProcess

时必须传递 Session 对象

class LogExportingProcess extends Thread 
{
    private HttpSession session;

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

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

和 ExportLogs class

中的一项更改

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

Answer 2

整数不可变。 AtomicInteger 将是一个不错的替代品。

@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
    }   
}

恕我直言，这比 Yogesh Badke 建议的持有对 HttpSession 对象的引用更可取，因为 HttpSession 可以在超时时正常被垃圾收集，并且 AtomicInteger 通过仅共享百分比而不是整个会话信息来增加封装。

我如何更改任意 java class 中的会话变量的值

How can i change the value of a session variable in an arbitrary java class

java

servlets

session-variables