Question

import com.sun.corba.se.spi.presentation.rmi.StubAdapter;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
@WebServlet(urlPatterns = {"/ShowPersonServlet"})
public class ShowPersonServlet extends HttpServlet {
String key = "";
String lastName = "";
String firstName="";
HttpSession session;
protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {


    response.setContentType("text/html;charset=UTF-8");
    key = request.getParameter("txt_Key");
    firstName = request.getParameter("txt_firstName");
    lastName = request.getParameter("txt_lastName");
    session = request.getSession();
    session.setAttribute("key", key);
    session.setAttribute("firstName", firstName);
    session.setAttribute("lastName", lastName);
    try (PrintWriter out = response.getWriter()) {
        /* TODO output your page here. You may use following sample code. */
        out.println("<!DOCTYPE html>");
        out.println("<html>");
        out.println("<head>");
        out.println("<title>Servlet ShowPersonServlet</title>");            
        out.println("</head>");
        out.println("<body>");
        out.println("<table border=\"1\" width =\"400\" height=\"30\" >");
        out.println(" <tbody>");



Enumeration e = session.getAttributeNames();
while ( e.hasMoreElements() )
{
        String k = (String)e.nextElement();
        Object value = session.getAttribute(k);

        String k2 = (String)e.nextElement();
        Object value2 = session.getAttribute(k2);

        String k3 = (String)e.nextElement();
        Object value3 = session.getAttribute(k3);
        out.println("<tr>");
        out.println("<td >"+ value +"</td>");
        out.println("<td >"+ value2 +"</td>");
        out.println("<td >"+ value3 +"</td>");
        out.println("</tr>");
        }
        out.println(" </tbody>");
        out.println("</table>");
        out.println("<br>");
        out.println("<form method=\"get\" action=\"ShowPersonServlet\">");
        out.println("<table width=\"1200\"  border=\"0\" cellpadding=\"2\" cellspacing=\"2\">");
        out.println("<tbody>\n" +
"    <tr>\n" +
"      <td><label>Key=</label><br>\n" +
"      </td>\n" +
"      <td><input name=\"txt_Key\"><br>\n" +
"      </td>\n" +
"      <td>First Name=<br>\n" +
"      </td>\n" +
"      <td><input name=\"txt_firstName\"><br>\n" +
"      </td>\n" +
"      \n" +
"      <td >Last Name=</td>\n" +
"      <td><input name=\"txt_lastName\"><br>\n" +
"      </td>\n" +
"      <td><button type=\"submit\">Add</button><br>\n" +
"      </td>\n" +
"    </tr>\n" +
"  </tbody>\n" +
"</table>");

        out.println("</form>");
        out.println("</body>");

        out.println("</html>");
    }
}

}

我想在每次填充文本字段时将（键名和姓）添加到上表中，然后通过将它们存储在会话中来按添加。但问题是每次我添加新数据都会替换旧数据（没有创建新行!!）。请帮忙。！

Answer 1

创建一个具有所需属性的类，然后将该实例存储在会话中，并将键作为属性键存储，或者您也可以创建一个List并将该List存储在会话中。如下所示。

class Person { 
   String key = "";
   String lastName = "";
   String firstName="";

   //create setter/getter for attributes
}

然后在servlet中

Person person = new Person();
person.setKey(key)
person.setFirstName(firstName);
person.setLastName(lastName);

我建议维护List中的所有数据并将List添加到会话中。

List list = new ArrayList();
list.add(person);

session.setAttribute("list", list);

然后遍历列表以获取所有数据。您需要相应地修改servlet代码。

Answer 2

您必须将用户详细信息存储在应用程序上下文变量中，而不是存储在会话变量中。会话适用于每个用户。因此，所有用户的列表必须是应用程序作用域而不是会话作用域。有关详细信息，请参阅ServletContext api

如何在同一个java servlet中的几个httprequests之后获取会话的所有值？

2 个答案: