servlet到jsp传递值
[英]servlet to jsp pass value
问题描述
I want to simple pass value servlet to jsp page. 
我想简单地将值传递给jsp页面。 I want to run jsp file and onload data is display from getting servlet 我想运行jsp文件，并且从获取servlet显示onload数据
But I got null : "Servlet communicated message to JSP: null " 但我得到了null： "Servlet communicated message to JSP: null "
below is my code. 下面是我的代码。
java code java代码
package api;
public class ServletToJSP extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//communicating a simple String message.
String message = "Example source code of Servlet to JSP communication.";
request.setAttribute("message", message);
RequestDispatcher reqDispatcher = getServletConfig().getServletContext().getRequestDispatcher("javaPapers.jsp");
reqDispatcher.forward(request,response);
}
}
jsp file jsp文件
<%@ page import="api.ServletToJSP" language="java" %>
<html>
<body>
<%
String message = (String) request.getAttribute("message");
out.println("Servlet communicated message to JSP: "+ message);
// Vector vecObj = (Vector) request.getAttribute("vecBean");
// out.println("Servlet to JSP communication of an object: "+vecObj.get(0));
%>
</body>
</html>
web.xml web.xml中
<servlet>
<servlet-name>ServletToJSP</servlet-name>
<servlet-class>api.ServletToJSP</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>ServletToJSP</servlet-name>
<url-pattern>/ServletToJSP/*</url-pattern>
</servlet-mapping>
4 个解决方案
解决方案1
2
There are few things to change: 有一些事情需要改变：
In servlet 在servlet中
public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//communicating a simple String message.
String message = "Example source code of Servlet to JSP communication.";
request.setAttribute("message", message);
request.getRequestDispatcher("javaPapers.jsp").forward(request,response);
}
In jsp 在jsp中
<html>
<body>
Servlet communicated message to JSP: ${message}
</body>
</html>
Changes made: 做出的改变：
- In servlet, used request.getRequestDispatcher(String url) 在servlet中，使用了request.getRequestDispatcher（String url）
- In jsp, removed servlet import. 在jsp中，删除了servlet导入。
- In jsp, used EL to get attribute value. 在jsp中，使用EL来获取属性值。
解决方案2
0 2013-09-03 07:05:52
replace 更换
RequestDispatcher reqDispatcher = getServletConfig().getServletContext().getRequestDispatcher("javaPapers.jsp");
with 同
RequestDispatcher reqDispatcher = request.getRequestDispatcher("javaPapers.jsp");
解决方案3
0 2013-09-03 09:48:07
Passing the param using the request.setAttribute("message", message); 使用request.setAttribute("message", message);传递参数request.setAttribute("message", message); should work using this code: 应该使用此代码：
RequestDispatcher rd = getServletContext().getRequestDispatcher("yourPage.jsp");
rd.forward(request,response);
You can also pass the attribute using the URL in dispatcher : 您还可以使用调度程序中的URL传递属性：
RequestDispatcher rd = getServletContext().getRequestDispatcher("yourPage.jsp?message=some message");
rd.forward(request,response);
Also you can share info using session object. 您还可以使用会话对象共享信息。
session.setAttribute("message","your message");
And then retrieve it in jsp using: 然后使用以下命令在jsp中检索它：
String message=(String)session.getAttribute("message");
解决方案4
-1 2015-08-02 08:59:52
You have to use context path to get message from servlet to jsp. 您必须使用上下文路径从servlet获取消息到jsp。 This will definitely work I have done it. 这绝对有效，我已经做到了。
String msg = "Message from servlet to jsp";
response.sendRedirect(response.encodeRedirectURL(contextPath+"/report/test.jsp?msg="+msg));
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