java - 我想使用 session 存储将变量传递到另一个页面，它给了我java.lang.IllegalStateException

我对编程很陌生，我遇到了这个问题，我已经在互联网上搜索了，找不到我想要的答案。希望你能在这里帮助我。谢谢！

我正在尝试传递2个变量，即名称和名称。
（我正在使用mysql工作台作为我的数据库）。

我猜我的错误是有关的。

String email=request.getParameter("email");
String password=request.getParameter("password");

这是我的代码：

@WebServlet("/login")
public class loginServlet extends HttpServlet{
    @Resource(name="jdbc/eg3752")
    private DataSource usercatalogue;
    @Override
    protected void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException,IOException
    {

        String email=request.getParameter("email");
        String password=request.getParameter("password");

        Connection connection=null;
        Statement statement=null;
        ResultSet resultset=null;

        String login="SELECT * FROM customer where email='"+email+"'";

        try
        {
            connection=usercatalogue.getConnection();
            statement=connection.createStatement();
            resultset=statement.executeQuery(login);
            while(resultset.next())
                    {
                      // check if password is same in the database
                        if(password.equals(resultset.getString("password")))
                        {
                            HttpSession session =request.getSession();
                            session.setAttribute("name", resultset.getString("fullname"));
                            session.setAttribute("custid", resultset.getString("customerId"));
                            response.sendRedirect(this.getServletContext().getContextPath()+"/search.html");

                        }
                        else
                        {
                            response.sendRedirect(this.getServletContext().getContextPath() + "/login.html");
                        }
                    }



        }
        catch(Exception e)
        {
            e.printStackTrace();
            System.err.println(e.getMessage());
        }
    }
}

这是GlassFish Server 4上的错误

Severe:   java.lang.IllegalStateException
    at org.apache.catalina.connector.ResponseFacade.sendRedirect(ResponseFacade.java:518)
    at com.aleksi.loginServlet.doPost(loginServlet.java:58)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:707)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1682)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:318)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:160)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:734)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:673)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:99)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:174)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:357)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:260)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:188)
    at org.glassfish.grizzly.http.server.HttpHandler.runService(HttpHandler.java:191)
    at org.glassfish.grizzly.http.server.HttpHandler.doHandle(HttpHandler.java:168)
    at org.glassfish.grizzly.http.server.HttpServerFilter.handleRead(HttpServerFilter.java:189)
    at org.glassfish.grizzly.filterchain.ExecutorResolver$9.execute(ExecutorResolver.java:119)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeFilter(DefaultFilterChain.java:288)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.executeChainPart(DefaultFilterChain.java:206)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.execute(DefaultFilterChain.java:136)
    at org.glassfish.grizzly.filterchain.DefaultFilterChain.process(DefaultFilterChain.java:114)
    at org.glassfish.grizzly.ProcessorExecutor.execute(ProcessorExecutor.java:77)
    at org.glassfish.grizzly.nio.transport.TCPNIOTransport.fireIOEvent(TCPNIOTransport.java:838)
    at org.glassfish.grizzly.strategies.AbstractIOStrategy.fireIOEvent(AbstractIOStrategy.java:113)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.run0(WorkerThreadIOStrategy.java:115)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy.access$100(WorkerThreadIOStrategy.java:55)
    at org.glassfish.grizzly.strategies.WorkerThreadIOStrategy$WorkerThreadRunnable.run(WorkerThreadIOStrategy.java:135)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:564)
    at org.glassfish.grizzly.threadpool.AbstractThreadPool$Worker.run(AbstractThreadPool.java:544)
    at java.lang.Thread.run(Thread.java:745)

最佳答案

您没有包括堆栈跟踪的“ cause by”部分，这是重要的部分。

sendRedirect（）上的IllegalStateException与HTTP协议有关，并且在已经提交对客户端的响应时发生。当响应缓冲区达到最大大小或有人显式调用flush（）或将某些内容写入输出流并导致响应被提交时，通常会发生这种情况。

调用sendRedirect()后，添加return;，然后尝试。