如何编写hello world servlet示例

Question

javaclass

package com.example;

import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

// Extend HttpServlet class
public class Helloworld extends HttpServlet {
    private String message;

    public void init() throws ServletException {
        // Do required initialization
        message = "Hello World";
    }

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        // Set response content type
        response.setContentType("text/html");
        // Actual logic goes here.
        PrintWriter out = response.getWriter();
        out.println("<h1>" + message + "</h1>");
    }

    public void destroy() {
        // do nothing.
    }
}

web.xml中

<servlet>
        <servlet-name>HelloForm</servlet-name>
        <servlet-class>HelloForm</servlet-class>
    </servlet>

    <servlet-mapping>
        <servlet-name>HelloForm</servlet-name>
        <url-pattern>/HelloForm</url-pattern>
    </servlet-mapping>

给代码但是我运行项目没有输出来404错误是在网页中.我们还需要为servlet创建Jsp页面吗？我在Servlet中真的很新请帮忙怎么写hello world就是Servlet.

Answer 1

你已经创建了这样的servlet类:

public class Helloworld extends HttpServlet

但是在web.xml中你有这样的映射:

<servlet-class>HelloForm</servlet-class>

您需要具有相同的名称,因此您将收到404错误.将您的servlet名称更改为HelloForm或更改<servlet-class>为HelloWorldweb.xml