Java 服务器页面.如何将参数从一个 JSP 页发送到另一个 JSP 页

Java Server Pages. How to send parameters from one JSP page to another

本文关键字：JSP 一个另一个服务器参数 Java 更新时间：2023-09-26

所以我有两个JSP页面一种是注册.jsp由注册表组成。当用户单击注册页面上的提交按钮时，我正在调用第二个 JSP 页面.jsp。第二个 JSP 页用于将数据添加到数据库中。我想做的是从第二页回到上一页，并在注册成功与否时显示一条消息。其他一切都很好。正在将数据添加到数据库中。这是我的注册表，在单击提交按钮时调用其他jsp页面。

<head>
</head>
<%!
String val;
%>
<article class="registrationform">
    <%
//Here m trying to access the attribute val which is set in the 2nd jsp page and whose value is true or false depending on data is added successfully or not.
    val=(String)request.getSession().getAttribute("val");
    if(val.equals("true"))
    {
    %>
    <h2 color="blue">Registration Successfull </h2>
    <%
    }else if(val.equals("false"))
    {
    %>
        <h2 color="red">Registration Failed. Please Try Again</h2>
    <%
    } else{
    }
    %>
    <h2>Registration form</h2>
    <form class="registration form-horizontal" name="regform" method="post" action="http://localhost:8080/mysrc/vt/components/jsp/RegisterDataBase.jsp">
      <fieldset id="personalinfo">
        <legend>Personal Info</legend>
                <section class="row">
                    <label class="col col-lg-4 control-label" for="myfirstname">First Name</label>
                    <div class="controls">
                        <input class="col col-lg-8" type="text" name="myfirstname" id="myfirstname">
                    </div><!-- controls -->
                </section><!-- row -->
<section class="row">
                    <label class="col col-lg-4 control-label" for="mylastname">Last Name</label>
                    <div class="controls">
                        <input class="col col-lg-8" type="text" name="mylastname" id="mylastname" >
                    </div><!-- controls -->
                </section><!-- row -->

                <section class="row">
                    <label class="col col-lg-4 control-label" for="myemail">Email</label>
                    <div class="controls">
                        <input class="col col-lg-8" type="email" name="myemail" id="myemail" required autocomplete="off" />
                    </div><!-- controls -->
                </section><!-- row -->
                <section class="row">
                    <label class="col col-lg-4 control-label" for="mypassword">Password</label>
                    <div class="controls">
                        <input class="col col-lg-8" type="password" name="mypassword" id="mypassword" required autocomplete="off" />
                    </div><!-- controls -->
                </section><!-- row -->
      </fieldset><!-- personal info -->
      <fieldset id="otherinfo">
            <legend>Other Info</legend>
                <section class="row">
                  <label class="col col-lg-4 control-label" for="dateofbirth">D.O.B</label>
                    <div class="controls">
                        <input class="col col-lg-8" type="date" name="dateofbirth" id="dateofbirth" />
                    </div><!-- controls -->
                </section><!-- row -->
                                <section class="row">
            <label class="col col-lg-4 control-label">Gender</label>
                    <div class="controls col col-lg-8">
                        <label class="radio">
                            <input type="radio" name="gender" value="male" /> Male
                        </label>
                        <label class="radio">
                            <input type="radio" name="gender" value="female" /> Female
                        </label>
                    </div><!-- controls -->
                </section><!-- row -->

                <section class="row">
                    <label class="col col-lg-4 control-label" for="collegename">College</label>
                    <div class="controls">
                        <input class="col col-lg-8" type="text" name="college" id="collegename" />
                    </div><!-- controls -->
                </section><!-- row -->
                <section class="row">
                    <label class="col col-lg-4 control-label" for="myaddress">Address</label>
                    <div >
                        <textarea class="col col-lg-8" type="text" name="address" id="myaddress" rows="3"></textarea>
                    </div><!-- controls -->
                </section><!-- row -->
    </fieldset>
      <button class="btn" type="submit" >Submit</button>
    </form>
</article>

这是具有数据库连接的第二个 JSP 页面，其中数据被添加到数据库中。现在我想再次重定向回上一页并显示一个弹出窗口，指出注册成功是数据添加成功，否则失败。

<%@ page language="java" %>
<%@ page import="java.sql.*" %>
<%!     
    String myfirstname, mylastname, myemail, mypassword, dateofbirth, gender,college, address;  
    Connection con;
    PreparedStatement pst;
%>
<% 
myfirstname=request.getParameter("myfirstname");
mylastname=request.getParameter("mylastname");
myemail=request.getParameter("myemail");
mypassword=request.getParameter("mypassword");
dateofbirth=request.getParameter("dateofbirth");
gender=request.getParameter("gender");
college=request.getParameter("college");
address=request.getParameter("address");
        try{
                    Class.forName("sun.jdbc.odbc.JdbcOdbcDriver");
                    con=DriverManager.getConnection("jdbc:odbc:vtdsn");
                    pst=con.prepareStatement("insert into studentdetail values(?,?,?,?,?,?,?,?)");
                    }
                    catch(Exception e)
                    {
                        e.printStackTrace();
                    }
        try{
                     pst.setString(1,myfirstname);
                     pst.setString(2,mylastname);
                     pst.setString(3,myemail);
                     pst.setString(4,mypassword);
                     pst.setString(5,dateofbirth);
                     pst.setString(6,gender);
                     pst.setString(7,college);
                     pst.setString(8,address);
                     int i=pst.executeUpdate();
                     if(i>=1)
                     {
//this is what i tried to set an attribute as true is data is added successfully which is being accesses at the previous page but m getting errors.
                     //request.getSession().setAttribute("val", "true");
                     response.sendRedirect("http://localhost:8080/mysrc/vt/register.jsp");
                     }
                     else
                     {
                     response.sendRedirect("http://localhost:8080/mysrc/vt/error.html");
                     }
                    }
                    catch(Exception e){
                                        e.printStackTrace();
                                        }
%>

将参数从一个 jsp 发送到另一个 jsp 有三种方式：1.将参数存储在会话中，然后重定向，就像您所做的那样。2.在URL中设置参数，然后重定向。3. 将参数存储在请求中，并将请求转发到下一个 jsp。

据我所知，你的方式应该没问题，那么你得到了什么具体的错误？

此外val=（String）request.getSession（）.getAttribute（"val"）;此值可能为空所以if（val.equals（"true"））可以抛出 NullPointer 异常尝试if（"true".equals（val））代替