HttpServlet和JSP集成 [英] HttpServlet and JSP integration
问题描述
我想知道是否可以将自定义servlet逻辑与.jsp模板视图集成.例如，我有以下servlet:
I'm wondering is possible to integrate custom servlet logic with .jsp template view. For example I have the following servlet:
public class MyServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String name = "Mark";
}
}
，我想将name变量放在jsp文件(new.jsp)中，例如:
and I want to place name variable inside jsp file(new.jsp) like:
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>New</title>
</head>
<body>
<%= name %>
</body>
</html>
我的web.xml:
<servlet>
<servlet-name>MyServlet</servlet-name>
<jsp-file>/new.jsp</jsp-file>
</servlet>
<servlet-mapping>
<servlet-name>MyServlet</servlet-name>
<url-pattern>/new</url-pattern>
</servlet-mapping>
我不想在请求中放入name.
有帮助吗?
更新
非常感谢，但我仍然遇到麻烦. 首先，我更新了我的servlet:
Great thanks, but I'm still having a trouble. Firstly, I updated my servlet:
public class MyServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String name = "Mark";
request.setAttribute("name", name);
request.getRequestDispatcher("/WEB-INF/new.jsp").forward(request, response);
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String name = "Mark";
request.setAttribute("name", name);
request.getRequestDispatcher("/WEB-INF/new.jsp").forward(request, response);
}
}
我也改变了看法:
<%@page contentType="text/html" pageEncoding="UTF-8"%>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>New</title>
</head>
<body>
${name}
</body>
</html>
但是当我使用${name}时，没有任何显示.我以为我应该导入任何jstl，但是不幸的是，如果我使用<%= request.getAttribute("name") %>，我会得到null.
But when I use ${name} there's nothing displayed. I thought that I should import any jstl, but unfortunately if I use <%= request.getAttribute("name") %> I'm getting null.
更新2 终于解决了！是我的错，我忘了设置
UPDATE 2 Finally solved! It was my fault, I forgot set
<servlet>
<servlet-name>MyServlet</servlet-name>
<servlet-class>com.example.MyServlet</servlet-class>
</servlet>
推荐答案
您需要改为实现doGet()方法.普通的HTTP请求(单击链接，书签或直接在浏览器地址栏中输入URL)默认为GET方法.
You need to implement the doGet() method instead. A normal HTTP request (clicking a link, a bookmark or entering the URL straight in browser address bar) defaults to GET method.
为了使对象在预处理servlet中的JSP中可用，您需要将其设置为请求，会话或应用程序范围内的属性.最后，您需要将请求/响应转发到JSP，以便可以显示它.
In order to make objects available in JSP in a preprocessing servlet, you need to set it as an attribute in request, session or application scope. Finally you need to forward the request/response to the JSP so that it can be displayed.
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String name = "Mark";
request.setAttribute("name", name);
request.getRequestDispatcher("/WEB-INF/new.jsp").forward(request, response);
}
如果您按照以下步骤修复servlet映射
If you fix the servlet mapping as follows
<servlet>
<servlet-name>MyServlet</servlet-name>
<servlet-class>com.example.MyServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>MyServlet</servlet-name>
<url-pattern>/new</url-pattern>
</servlet-mapping>
然后，您可以通过 http://localhost:8080/contextname/new 来调用servlet. .在转发的JSP中，您可以仅通过EL
then you can just invoke the servlet by http://localhost:8080/contextname/new. In the forwarded JSP you can access the name just by EL
${name}
请注意，JSP放置在/WEB-INF文件夹中，以避免直接访问，而无需通过在浏览器地址栏中输入JSP URL来调用预处理servlet.
Note that the JSP is placed in /WEB-INF folder in order to avoid direct access without the preprocessing servlet being called by entering the JSP URL in browser address bar instead.
- Our Servlets wiki page
- Our Expression Language wiki page
- How to avoid Java code in JSP files?
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