1.求jsp登录源码 急急急急急急急急急急急
2.每次对jsp的引引擎请求都要将jsp转换为servlet吗？
3.JSP运行原理什么
求jsp登录源码 急急急急急急急急急急急
登陆页面 index.jsp源码：
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4. Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>login</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
<form action="LoginServlet" method="post">
用户名：<input type="text" name="username" ><br>
密码:<input type="password" name="userpass"><br>
<input type="submit" value="登陆"> <input type="reset" value="取消">
</form>
</body>
</html>
-------------
LoginServlet.java 源码：
package servlet;
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 LoginServlet extends HttpServlet {
/
*** Constructor of the object.
*/
public LoginServlet() {
super();
}
/
*** Destruction of the servlet. <br>
*/
public void destroy() {
super.destroy(); // Just puts "destroy" string in log
// Put your code here
}
/
*** The doGet method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to get.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//获得jsp页面传输的参数
String username=request.getParameter("username");
String userpass=request.getParameter("userpass");
//判断
if(username.equals("user")&&userpass.equals("")){
response.sendRedirect("1.jsp");
}else if(username.equals("admin")&&userpass.equals("")){
response.sendRedirect("2.jsp");
}else{
response.sendRedirect("index.jsp");
}
}
/
*** The doPost method of the servlet. <br>
*
* This method is called when a form has its tag value method equals to post.
*
* @param request the request send by the client to the server
* @param response the response send by the server to the client
* @throws ServletException if an error occurred
* @throws IOException if an error occurred
*/
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
/
*** Initialization of the servlet. <br>
*
* @throws ServletException if an error occurs
*/
public void init() throws ServletException {
// Put your code here
}
}
-------------
1.jsp:
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4. Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP '1.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
This is 1.jsp <br>
</body>
</html>
-------------
2.jsp
<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4. Transitional//EN">
<html>
<head>
<base href="<%=basePath%>">
<title>My JSP '1.jsp' starting page</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
<meta http-equiv="description" content="This is my page">
<!--
<link rel="stylesheet" type="text/css" href="styles.css">
-->
</head>
<body>
This is 2.jsp <br>
</body>
</html>
每次对jsp的请求都要将jsp转换为servlet吗？
在处理动态网页请求时，如ASP、擎源ASP.NET、引引擎JSP、擎源PHP等，引引擎每次客户端对JSP的擎源语义解析公式源码请求确实需要将其转换为Servlet。这是引引擎因为，JSP本质上是擎源一种模板引擎，用于生成动态网页内容。引引擎它的擎源源代码首先会被JSP引擎编译为Servlet，即一个Java类，引引擎这个过程发生在服务器端。擎源Servlet作为Java的引引擎Web应用组件，能够执行Java代码，擎源处理客户端请求并生成响应结果。引引擎php 统计报表源码因此，为了使JSP能够运行服务器端代码并生成动态网页内容，其源代码必须先转换为Servlet。
当用户请求一个JSP页面时，Web服务器（如Tomcat、Jetty等）接收到请求后，会调用JSP引擎来处理该请求。java的helloworld源码JSP引擎首先解析JSP页面的HTML和脚本元素，然后将这些元素转换为一个Java类，这个过程即编译阶段。在编译过程中，JSP引擎会检查JSP页面中是否存在脚本元素，并将它们转换为Java代码。然后，珠峰源码站这个Java类会被JVM解释执行，生成动态内容，并最终以HTML格式返回给客户端浏览器。
简而言之，每次对JSP的请求都要将其转换为Servlet，这是因为JSP本身不具备直接执行服务器端代码的能力。通过将JSP源代码转换为Servlet，网页源码正则匹配Web服务器能够执行Java代码，处理动态请求并生成响应内容。这一过程确保了动态网页能够根据用户请求生成个性化、动态的网页内容，从而实现丰富的Web应用功能。
JSP运行原理什么
JSP运行的底层机制可以概括为以下几个步骤：首先，当服务器接收到JSP请求时，JSP引擎会对JSP文件进行初步处理。这个阶段，JSP引擎会尝试将JSP代码转换为Java源代码，任何语法错误都会立即引发转换中断，并在客户端和服务端显示出错信息。
一旦转换顺利，JSP引擎会利用Java编译器Javac将生成的Java源文件编译成Class文件，这是一种可执行的二进制格式。这一步确保了代码的高效执行，为系统提供了更好的并发处理能力，提升了响应速度。然而，值得注意的是，多线程技术虽然能提升性能，但同时也需要开发者严格遵守编程规范，因为多线程环境可能会带来并发问题和资源管理挑战。因此，在设计多线程应用时，理解并遵循相关约束是至关重要的。
