Sevlet局部变量初始化

//java 代码部分
package com.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.Enumeration;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class InitParamServlet extends HttpServlet {
　　　　　//登录窗口
	private static final long serialVersionUID = 1L;
	public void doGet(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setCharacterEncoding("utf-8");
		request.setCharacterEncoding("utf-8");

		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
		out.println("<HTML>");
		out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
		out.println("  <BODY>");

		out.println("<form action='"+request.getRequestURL()+"' method='post'>");
		out.println("帐号：<input type='text' name='username' style='width:200px'><br/>");
		out.println("密码：<input type='password' name='password' style'width:200px'>");
		out.println("<input type='submit' value='登录'> </form>");

		out.println("  </BODY>");
		out.println("</HTML>");
		out.flush();
		out.close();
	}
        //验证正确后跳转notice.jsp 登录失败后执行this.doGet（）方法	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {

		response.setContentType("text/html");
		PrintWriter out = response.getWriter();
		out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
		out.println("<HTML>");
		out.println("  <HEAD><TITLE>A Servlet</TITLE></HEAD>");
		out.println("  <BODY>");

		String username=request.getParameter("username");
		String password=request.getParameter("password");
		Enumeration params=this.getInitParameterNames();
		while(params.hasMoreElements()){
			String usernameParam=(String)params.nextElement();
			String passwordParam=getInitParameter(usernameParam);

			if(usernameParam.equalsIgnoreCase(usernameParam) && passwordParam.equalsIgnoreCase(password)){
				request.getRequestDispatcher("/WEB-INF/notice.jsp").forward(request, response);//前往
				return;
			}
		}
		this.doGet(request, response);
	}
}

web.xml部分

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5" 
    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">
<display-name></display-name>
<servlet>
<servlet-name>InitParamServlet</servlet-name>
<servlet-class>com.servlet.InitParamServlet</servlet-class>
<init-param>
<param-name>user1</param-name>
<param-value>123</param-value>
</init-param>

<init-param>
<param-name>user2</param-name>
<param-value>123</param-value>
</init-param>
<load-on-startup>0</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>InitParamServlet</servlet-name>
<url-pattern>/servlet/InitParamServlet</url-pattern>
</servlet-mapping>    
<welcome-file-list>
<welcome-file>index.jsp</welcome-file>
</welcome-file-list>
</web-app>

核心代码讲解：

Enumeration params=this.getInitParameterNames();//获取web.xml中设置的全部初始值

params.hasMoreElements()//遍历params

秒客网

Sevlet局部变量初始化

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