Java 如何从以前的jsp页面检索值到结果页面？
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How to retrieve the values from previous jsp page to result page?
提问by Dinesh Kumar
I am creating a quiz application. Here, there are 5 jsp pages with 5 different quizes. If I use 1 jsp page and result page, it is working fine..i.e; It is redirecting from QuizPage5.jsp and show the result in ResultPage.jsp. I need to show all the results from QuizPage1.jsp, QuizPage2.jsp, QuizPage3.jsp, QuizPage4.jsp and QuizPage5.jsp to ResultPage.jsp.
我正在创建一个测验应用程序。这里有 5 个 jsp 页面，有 5 个不同的测验。如果我使用 1 个 jsp 页面和结果页面，它工作正常..ie; 它从 QuizPage5.jsp 重定向并在 ResultPage.jsp 中显示结果。我需要显示从 QuizPage1.jsp、QuizPage2.jsp、QuizPage3.jsp、QuizPage4.jsp 和 QuizPage5.jsp 到 ResultPage.jsp 的所有结果。
I used
我用了
in jsp1 to pass value.
在jsp1中传递值。
<form action="">
<input type="hidden" name="hidden" value="hidden">
<input type="submit" value="submit"></form>
in jsp2 to get value
在jsp2中获取值
String value=request.getParameter("hidden");
But, I am getting java.lang.NullPointerException
但是，我得到 java.lang.NullPointerException
Here is my code..
这是我的代码..
QuizPage1.jsp
测验页面1.jsp
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script language="JavaScript">
function check()
{
var radio_choice = false;
for (counter = 0; counter < myform.grp.length; counter++)
{
if (myform.grp[counter].checked)
radio_choice = true;
}
if (!radio_choice)
{
alert("Please select one.")
return (false);
}
return(true);
}
</script>
</head>
<body>
<h3>Quiz No.1</h3>
Q1.Which one of the following is the Capital of India?<br><br>
<form action="QuizPage2.jsp" method="post" name="myform" onsubmit="return check();">
<input type="radio" name="grp" value="New Delhi" >New Delhi<br>
<input type="radio" name="grp" value="Kolkata" >Kolkata<br>
<input type="radio" name="grp" value="Chennai" >Chennai<br>
<input type="radio" name="grp" value="Mumbai" >Mumbai<br>
<br><br><input type="submit" value="Next Question">
<input type="hidden" name="hidden" value="grp">
<input type="submit" value ="Back" onclick="window.history.back();"/>
</form>
</body>
</html>
QuizPage2.jsp
测验页面2.jsp
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script language="JavaScript">
function check()
{
var radio_choice = false;
for (counter = 0; counter < myform2.grp2.length; counter++)
{
if (myform2.grp2[counter].checked)
radio_choice = true;
}
if (!radio_choice)
{
alert("Please select any one Answer");
return (false);
}
return(true);
}
</script>
</head>
<body>
<h3>Quiz No.2</h3>
Q2. Where is Chennai Located?<br><br>
<form action="QuizPage3.jsp"method="post" name="myform2" onsubmit="return check();">
<input type="radio" name="grp2" value="Karnataka" >Karnataka<br>
<input type="radio" name="grp2" value="Tamilnadu" >Tamilnadu<br>
<input type="radio" name="grp2" value="Andhra Pradesh" >Andhra Pradesh<br>
<input type="radio" name="grp2" value="Maharashtra" >Maharashtra<br>
<br><br><input type="submit" value="Next Question">
<input type="hidden" name="hidden" value="grp2">
<input type="submit" value ="Back" onclick="window.history.back();"/>
</form>
<%
String s1=request.getParameter("grp");
%>
</body>
</html>
QuizPage3.jsp
QuizPage3.jsp
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script language="JavaScript">
function check()
{
var radio_choice = false;
for (counter = 0; counter < myform3.grp3.length; counter++)
{
if (myform3.grp3[counter].checked)
radio_choice = true;
}
if (!radio_choice)
{
alert("Please select any one Answer");
return (false);
}
return(true);
}
</script>
</head>
<body>
<h3>Quiz No.3</h3>
Q3. What is the largest state in the USA<br><br>
<form action="QuizPage4.jsp"method="post" name="myform" onsubmit="return check();">
<input type="radio" name="grp3" value="New York" >New York<br>
<input type="radio" name="grp3" value="Alaska" >Alaska<br>
<input type="radio" name="grp3" value="California" >California<br>
<input type="radio" name="grp3" value="Melbourne" >Melbourne<br>
<br><br><input type="submit" value="Next Question">
<input type="hidden" name="hidden" value="grp3">
<input type="submit" value ="Back" onclick="window.history.back();"/>
</form>
<%
String s2=request.getParameter("grp2");
%>
</body>
</html>
QuizPage4.jsp
测验页面4.jsp
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script language="JavaScript">
function check()
{
var radio_choice = false;
for (counter = 0; counter < myform4.grp4.length; counter++)
{
if (myform4.grp4[counter].checked)
radio_choice = true;
}
if (!radio_choice)
{
alert("Please select any one Answer");
return (false);
}
return(true);
}
</script>
</head>
<body>
<h3>Quiz No.4</h3>
Q4. The famous Dilwara Temples are situated in<br><br>
<form action="QuizPage5.jsp"method="post" name="myform" onsubmit="return check();">
<input type="radio" name="grp4" value="Uttar Pradesh" >Uttar Pradesh<br>
<input type="radio" name="grp4" value="Maharashtra" >Maharashtra<br>
<input type="radio" name="grp4" value="Andhra Pradesh" >Andhra Pradesh<br>
<input type="radio" name="grp4" value="Rajasthan" >Rajasthan<br>
<br><br><input type="submit" value="Next Question">
<input type="hidden" name="hidden" value="grp4">
<input type="submit" value ="Back" onclick="window.history.back();"/>
</form>
<%
String s3=request.getParameter("grp3");
%>
</body>
</html>
QuizPage5.jsp
QuizPage5.jsp
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script language="JavaScript">
function check()
{
var radio_choice = false;
for (counter = 0; counter < myform5.grp5.length; counter++)
{
if (myform5.grp5[counter].checked)
radio_choice = true;
}
if (!radio_choice)
{
alert("Please select any one Answer");
return (false);
}
return(true);
}
</script>
</head>
<body>
<h3>Quiz No.5</h3>
Q5. The Indian Institute of Science is located at<br><br>
<form action="ResultPage.jsp"method="post" name="myform" onsubmit="return check();">
<input type="radio" name="grp5" value="Chennai" >Chennai<br>
<input type="radio" name="grp5" value="Bangalore" >Bangalore<br>
<input type="radio" name="grp5" value="Mumbai" >Mumbai<br>
<input type="radio" name="grp5" value="Hyderabad" >Hyderabad<br>
<br><br><input type="submit" value="Show Result">
<input type="hidden" name="hidden" value="grp5"/>
</form>
<%
String s4=request.getParameter("grp4");
%>
</body>
</html>
ResultPage.jsp
结果页面.jsp
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Quiz Result</title>
</head>
<body>
<%
String answer="New Delhi";
String s1=request.getParameter("grp");
if(s1.equals(answer))
{
out.println("Correct Answer");
}
else
{out.println("Wrong Answer! The Correct Answer is :"+answer);
}
%>
<%
String answer2="Tamilnadu";
String s2=request.getParameter("grp2");
if(s2.equals(answer2))
{
out.println("Correct Answer");
}
else
{out.println("Wrong Answer! The Correct Answer is :"+answer2);
}
%>
<%
String answer3="Alaska";
String s3=request.getParameter("grp3");
if(s3.equals(answer3))
{
out.println("Correct Answer");
}
else
{out.println("Wrong Answer! The Correct Answer is :"+answer3);
}
%>
<%
String answer4="Rajasthan";
String s4=request.getParameter("grp4");
if(s4.equals(answer4))
{
out.println("Correct Answer");
}
else
{out.println("Wrong Answer! The Correct Answer is :"+answer4);
}
%>
<%
String answer5="Bangalore";
String s5=request.getParameter("grp5");
if(s5.equals(answer5))
{
out.println("Correct Answer");
}
else
{out.println("Wrong Answer! The Correct Answer is :"+answer5);
}
%>
</body>
</html>
Your help is highly appreciated. Thanks in Advance
非常感谢您的帮助。提前致谢
采纳答案by EJK
If you want data that can be access across multiple pages, consider using the session to store data. For example, if page1.jsp submits a form parameter, "page1Result" to page2.jsp, then in page2.jsp, do the following:
如果您希望可以跨多个页面访问数据，请考虑使用会话来存储数据。例如，如果 page1.jsp 向 page2.jsp 提交表单参数“page1Result”，则在 page2.jsp 中执行以下操作：
String page1Result = request.getParameter("page1Result");
request.getSession().setAttribute("page1Result", page1Result);
Then at some point down the road (say on page 5), you can access the page1 value as follows:
然后在路上的某个点（比如第 5 页），您可以按如下方式访问 page1 值：
String page1Value = (String)request.getSession().getAttribute("page1Result);
================================================================================ So applying this to your code:
================================================== ============================== 所以将这个应用到你的代码中：
In page2 jsp, change the scriptlet at the end of the file to:
在 page2 jsp 中，将文件末尾的 scriptlet 更改为：
<%
String s1=request.getParameter("grp");
request.getSession().setAttribute("s1", s1);
%>
And in page 3 JSP, change the script let to:
在第 3 页 JSP 中，将脚本 let 更改为：
<%
String s2=request.getParameter("grp2");
request.getSession().setAttribute("s2", s2);
%>
And so on.
等等。
And finally on ResultPage.jsp (just showing example one line for answer 2)
最后在 ResultPage.jsp （仅显示答案 2 的示例一行）
out.println("Wrong Answer! The Correct Answer for question 2 is :"+session.getAttribute("s2"));
回答by Hussain Akhtar Wahid 'Ghouri'
on jsp1
在jsp1上
String passThis = "pass this value";
request.setAttribute("param1",passThis);
dispatch to jsp 2
分派到jsp 2
in jsp2
在jsp2中
String getParam = request.getAttribute("param1");
回答by Alex
Switch questions by JavaScriptand submit everything at once.
切换问题JavaScript并立即提交所有内容。
回答by Himanshu Bhardwaj
I have not detailed look on the code. But the question requires a multiple request paradigm. But result.jsp though takes all the answer from request object. Whereas it should be the session object. And answer to each question should be stored in session. So it is accessible and doesn't gets descoped.
我没有详细看代码。但是这个问题需要一个多请求范式。但是 result.jsp 虽然从请求对象中获取了所有答案。而它应该是会话对象。并且每个问题的答案都应该存储在会话中。所以它是可访问的并且不会被分解。
