[英]Java Servlet JSP does not print out attribute
我正在嘗試使用生成的HTML代碼編寫servlet,而不是打印出靜態HTML。
我正在使用Eclipse-EE Europa和Tomcat 6。
我嘗試使用這里的技巧
但是,而不是打印所需的屬性似乎忽略屬性的jsp或屬性為空。
這是servlet:
package com.serv.pac;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.PrintWriter;
/**
* Servlet implementation class for Servlet: testServlet
*
*/
public class testServlet extends javax.servlet.http.HttpServlet implements javax.servlet.Servlet {
static final long serialVersionUID = 1L;
/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#HttpServlet()
*/
public testServlet() {
super();
}
/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
*/
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String message = "doGet response";
request.setAttribute("message", message);
request.getRequestDispatcher("/testServlet/WEB-INF/index1.jsp").forward(request, response);
PrintWriter out = response.getWriter();
out.println("the servlet");
}
/* (non-Java-doc)
* @see javax.servlet.http.HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
*/
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
System.out.println("first servlet");
}
}
這是JSP
<!doctype html>
<html lang="en">
<head>
<title>SO question 2370960</title>
</head>
<body>
<p>Message: ${message}</p>
</body>
</html>
以下是:
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
<display-name>servlet1_test</display-name>
<welcome-file-list>
<welcome-file>index.html</welcome-file>
<welcome-file>index.htm</welcome-file>
<welcome-file>index.jsp</welcome-file>
<welcome-file>default.html</welcome-file>
<welcome-file>default.htm</welcome-file>
<welcome-file>default.jsp</welcome-file>
<welcome-file>index1.jsp</welcome-file>
</welcome-file-list>
<servlet>
<description></description>
<display-name>testServlet</display-name>
<servlet-name>testServlet</servlet-name>
<servlet-class>com.serv.pac.testServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>testServlet</servlet-name>
<url-pattern>/testServlet</url-pattern>
</servlet-mapping>
</web-app>
那就是我在瀏覽器中得到的:
<!doctype html>
<html lang="en">
<head>
<title>SO question 2370960</title>
</head>
<body>
<p>Message: </p>
</body>
</html>
可以看到,html正文中的“消息”之后沒有任何內容,好像message屬性為空。
謝謝
我看到這種情況的唯一方法是您實際上並沒有訪問Servlet
。
您已聲明<welcome-file>
<welcome-file>index1.jsp</welcome-file>
所以如果你想打
localhost:8080/YourContextPath
默認的Servlet
將呈現缺少message
屬性的jsp並將其發送給您。
如果您想使用實際的Servlet
,則需要使用
localhost:8080/YourContextPath/testServlet
請注意,您需要更改
request.getRequestDispatcher("/testServlet/WEB-INF/index1.jsp").forward(request, response);
至
request.getRequestDispatcher("/WEB-INF/index1.jsp").forward(request, response);
並將文件移到WEB-INF
。
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