servlet-保持前端请求方式和后台处理方式方式一致 2

程序员文章站 2022-07-12 15:48:17

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上一篇文章说到LoginServlet和LogoutServlet的所需要的的请求方式不一样（一个是POST请求，一个是GET请求），为了前后台的一致，需要判断，但是每一个Servlet都要写相同的代码。
有时间可以看看sun公司写的HttpServlet的类，远比下边的这个要详细
我们可以写一个父类，继承GenericServlet，再让LoginServlet和LogServlet继承我们所写的这个父类就好了。
我们起名这个父类就叫HttpServlet
HttpServlet

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.GenericServlet;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class HttpServlet extends GenericServlet {

	@Override
	public void service(ServletRequest req, ServletResponse res) throws ServletException, IOException {
		HttpServletRequest request = (HttpServletRequest)req;
		HttpServletResponse response = (HttpServletResponse)res;
		
		service(request,response);			
	}
	public void service(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException{
		
		String method = request.getMethod();
		if("GET".equals(method))
		{
			doGet(request,response);
		}else if("POST".contentEquals(method)) {
			doPost(request,response);
		}
	}
	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException{
		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out = response.getWriter();
		out.print("405-您应该发送GET请求");
		throw new RuntimeException("405-您应该发送GET请求");
		
	}
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException{
		response.setContentType("text/html;charset=UTF-8");
		PrintWriter out = response.getWriter();
		out.print("405-您应该发送POST请求");
		throw new RuntimeException("405-您应该发送POST请求");
	}
}

LoginServlet

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginServlet extends HttpServlet {

public void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {	
		response.getWriter().print("login....");	
	}
}

LogoutServlet

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LogoutServlet extends HttpServlet {
	@Override
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		response.getWriter().print("系统正在安全退出");
	}
}

html文件

<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>login page</title>
</head>
<body>
	<form action="/08-HttpServlet原理/login" method="get">
		username<input type="text" name="username"><br>
		password<input type="password" name="password"><br>
		<input type="submit" value="login">
	</form>
	
	<!-- 安全退出系统 /logout-->
	<form action="/08-HttpServlet原理/logout" method="post">
		<input type="submit" value="退出系统">
	</form>
	
</body>
</html>

xml文件

<?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"
	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">
	<welcome-file-list>
		<welcome-file>login.html</welcome-file>
	</welcome-file-list>
	<servlet>
		<servlet-name>login</servlet-name>
		<servlet-class>com.servlet.LoginServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>login</servlet-name>
		<url-pattern>/login</url-pattern>
	</servlet-mapping>
	
	<servlet>
		<servlet-name>logout</servlet-name>
		<servlet-class>com.servlet.LogoutServlet</servlet-class>
	</servlet>
	<servlet-mapping>
		<servlet-name>logout</servlet-name>
		<url-pattern>/logout</url-pattern>
	</servlet-mapping>
	
</web-app>

servlet-保持前端请求方式和后台处理方式方式一致 2

servlet-保持前端请求方式和后台处理方式方式一致 1

servlet-保持前端请求方式和后台处理方式方式一致 2