CODEWITHSUNDEEP
htmleclipsetomcatservlets
Michael Lai
Michael Lai

Reputation: 177

How to set up the Servlet Path make HTML correctly invoke servlet file?

My goal: to access a .htm file, and pass the user input to the invoked servlet and display the content.

What i did: I used eclipse Juno to create a dynamic project:ServeletTest. The structure of the project is as followed:

enter image description here

The servlet file is MyServlet.java and the related code is:

package ylai.Servlet.test;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.PrintWriter;
/**
 * Servlet implementation class MyServlet
 */
@WebServlet(description = "test servlet", urlPatterns = { "/MyServlet" })
public class MyServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    /**
     * @see HttpServlet#HttpServlet()
     */
    public MyServlet() {
        super();
        // TODO Auto-generated constructor stub
    }

    /**
     * @see HttpServlet#doGet(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        String info = request.getParameter("info") ;    
        PrintWriter out = response.getWriter() ;
        out.println("<html>") ;
        out.println("<head><title>Hello Servlet</title></head>") ;
        out.println("<body>") ;
        out.println("<h1>" + info + "</h1>") ;
        out.println("</body>") ;
        out.println("</html>") ;
        out.close() ;

    }

    /**
     * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse response)
     */
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
           this.doGet(request, response);
    }


}

The html file is input.htm . And the detail code is:

<html>
<head><title>This is html file</title></head>
<body>
<form action="myservlet" method="post">
    Type something：<input type="text" name="info">
    <input type="submit" value="submit">
</form>
</body>
</html>

And the web.xml is defined as :

<web-app xmlns="http://java.sun.com/xml/ns/javaee"
   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
   xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd"
   version="2.5">

  <display-name>Welcome to Tomcat</display-name>
  <description>
     Welcome to Tomcat
  </description>    
    <servlet>
        <servlet-name>myservlet</servlet-name>
        <servlet-class>ylai.Servlet.test.MyServlet</servlet-class>
    </servlet>
    <servlet-mapping>
        <servlet-name>myservlet</servlet-name>
        <url-pattern>/myservlet</url-pattern>
    </servlet-mapping>  
    </web-app>

When i run the input.htm using Built-in Tomcat within the Eclipse, it works fine, and the input content in the input.htm can be displayed by MyServlet.java. The screen shot is as followed:

enter image description here

enter image description here

It seems works fine.

My Question:

If i want to modify the value of in the web.xml as

 <servlet-mapping>
        <servlet-name>myservlet</servlet-name>
        <url-pattern>/myservletURL</url-pattern>
    </servlet-mapping>

What i expected was once the input.htm is submitted, it will invoked the serlvet and the web page address should be:

http://localhost:8080/ServeletTest/myservletURL

But the display page address is still, does not change :

http://localhost:8080/ServeletTest/myservlet with HTTP Status 404 error.

It looks weird!!! The mechanism should be: When i submit the input.htm page, it will invoke servlet by servlet-name in the web.xml. In this case, servlet-name is myservlet. Tomcat will use servlet-name to find the actual location of servlet file: MyServlet.java and execute it. The redirect page address would be depends on what you define in . In this case, it should /ServeletTest/myservletURL But right now. Servlet file can not be invoked and the page address is not what i expect.

Do i have wrong understand on the servlet invoke mechanism or others?

Upvotes: 0

Views: 23358

Answers (2)

sunleo
sunleo

Reputation: 10943

LifeCycleServlet--@WebServlet("/LifeCycleServlet")
MyServlet--@WebServlet(description = "test servlet", urlPatterns = { "/MyServlet" })

delete these lines because here you have mentioned url as MyServlet

or

Change this urlpattern { "/MyServlet" } also

Upvotes: 1

user553180
user553180

Reputation: 626

If you changed the url-pattern to myservletURL, you will also need to update the form action to target this new url.

Upvotes: 2

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