"Head First Servlet and JSP"示例不起作用

大家好，我正在读一本jsp书"Head First Servlet and jsp"，下一个例子不起作用。。。

html代码：

<!DOCTYPE html>
<html>
<head>
<meta charset="windows-1255">
<title>Insert title here</title>
</head>
<body>
<h1 style="text-align: center;">Beer Selection Page</h1>
<br><br>
<form method = "POST" action="SelectBeer.do">
  Select beer characteristics<p>
  Color:
<select name ="color" size="1">
  <option value="light">light</option>
  <option value="amber">amber</option>
  <option value="brown">brown</option>
  <option value="dark">dark</option>
</select>
<br><br>
<div style="text-align:center">
<input type = "SUBMIT">
</div>
</form>
</body>
</html>

Web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" 
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"  
 xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
 <servlet>     
  <servlet-name>Ch3 Beer</servlet-name> 
  <servlet-class>com.example.web.BeerSelect</servlet-class> 
 </servlet>   
 <servlet-mapping>    
    <servlet-name>Ch3 Beer</servlet-name>      
    <url-pattern>/SelectBeer.do</url-pattern>  
 </servlet-mapping> 
 </web-app>

Servlet代码：

package com.example.web;
import javax.servlet.*; 
import javax.servlet.http.*;
import java.io.*; 

public class BeerSelect extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws     ServletException, IOException
{
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    out.println("Beer Selection Advice<br>"); 
    String c = request.getParameter("color");  
    out.println("<br>Got beer color " + c);
}
}

当我运行它时，我得到。。。"HTTP状态405-此URL不支持HTTP方法GET"。。。我急需帮助。提前感谢您的帮助！！

您可以通过向servlet添加"doGet"方法来修复此问题。使用与doPost:相同的方法签名

protected void doGet(HttpServletRequest request, HttpServletResponse response) throws     ServletException, IOException

您所编码的内容只包括一个doPost方法。因此servlet将只响应HTTPPOST请求。HTTP 405响应代码是servlet引擎告知客户端不支持HTTP GET的方式。

您已经编写了所有内容，但在servlet代码中需要进行更改：

Servlet代码：

package com.example.web;
import java.io.IOException;
import java.io.PrintWriter; 
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class BeerSelect extends HttpServlet {
private static final long serialVersionUID = 1L;
public BeerSelect() {
    super();
 }
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    response.setContentType("text/html");
    PrintWriter out = response.getWriter();
    out.println("Beer Selection Advice<br>"); 
    String c = request.getParameter("color");  
    out.println("<br>Got beer color " + c);
}
}

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