jsp+servlet 实现登录功能

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mb60b8936aed2b7 2021-06-04 15:06:11 ©著作权

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现在的框架比较流行，为了更好的理解框架，javaweb的基本开发形式还需要了解。

下面是运用jsp+servlet技术是实现登录。（没有运用数据库，数据操作比较简单，这个例子主要描述开发流程）

project:jspServletLoginTest

项目的目录结构如下：

jsp+servlet 实现登录功能_JS开发

下面贴上代码：

index.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<!-- 该Login页面是一个简单的登录界面 --> 
<html > 
   <head> 
     <title>Login</title> 
     <meta http-equiv= "content-type" content = "text/html; charset=UTF-8"> 
     <meta http-equiv= "Content-Language" content = "ch-cn"> 
   </head> 
   <body > 
  <!-- Form 用来提取用户填入并提交的信息--> 
  <form method = "post" name = "frmLogin" action="loginServlet"> 
    <h1 align = "center"> USER LOGIN</h1> <br > 
    <div align = "center" > User name：
      <input type = "text" name = "txtUserName" value = "hym" 
        size = "20" maxlength = "20"  > <br> Password：
      <input type = "password" name = "txtPassword" value = "Your password" 
        size = "20" maxlength = "20" > <br> 
       <input type = "submit" name = "Submit" 　value= "submit" onClick = "validateLogin();" > 
       <input type = "reset" name = "Reset" value = "reset" > <br> 
    </div> 
  </form> 
  <!-- javaScript 函数 validateLogin(),null validate--> 
     <script language = "javaScript"> 
      function validateLogin( ) 
      { 
       var sUserName = document. frmLogin. txtUserName. value ; 
       var sPassword = document. frmLogin. txtPassword. value ; 
       if( sUserName= = "" ) 
       { 
        alert( "input user name！" ) ; 
        return false; 
       } 
       if( sPassword= = "" ) 
       { 
        alert( "input password！" ) ; 
        return false; 
       } 
      } 
     </script> 
   </body> 
</html>

login_success.jsp

<%@ page language= "java" contentType= "text/html; charset=UTF-8" pageEncoding= "UTF-8" %> 
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" > 
<html> 
  <head> 
   <title> My JSP 'login_failure.jsp' starting page </title> 
   <meta http-equiv= "content-type" content = "text/html; charset=UTF-8"> 
   <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"> 
  </head> 
  <body> 
   <% 
    String userName = ( String ) session. getAttribute ( "UserName" ) ; 
   %> 
   <div align = center> 
    <%=userName%> 
    welcome,logined!
  </div> 
  </body> 
</html>

login_failure.jsp

<%@page language= "java" contentType= "text/html; charset=UTF-8" pageEncoding= "UTF-8" %> 
<! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"> 
<html> 
  <head> 
   <title> My JSP 'login_failure.jsp' starting page </title> 
   <meta http-equiv= "content-type" content = "text/html; charset=UTF-8"> 
   <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"> 
  </head> 
  <body> 
   <% 
   String userName = ( String ) session. getAttribute ( "UserName" ) ; 
   %> 
   <div align = center> 
    <%=userName%> 
  failure access!
  </div> 
  </body> 
</html>

servlet类，表单的数据需要提交到这个类进行处理（页面跳转的控制类），若要深入理解Form的提交和处理原理，则需要深入研究web的HTTP协议

loginServlet.java

package test.login;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class loginServlet extends HttpServlet {
	private static final long serialVersionUID = 1L;
       
    public loginServlet() {
        super();
    }
	protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
	
	}
	protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
		   response. setContentType ( "text/html" ) ; 
		   // get username
		   String sUserName = request.getParameter("txtUserName") ; 
		   // get password
		   String sPasswd = request.getParameter("txtPassword") ;  
		   //test
		   System.out.println("username:"+sUserName+"\r\n"+"password:"+sPasswd);
		   request . getSession( ).setAttribute ( "UserName" , sUserName ) ; 
		   request.getSession().setAttribute("password", sPasswd);
		   //just compare with hym&123,not do database operation
		   if(sUserName.equals("hym")&&sPasswd.equals("123"))
		   {
			   response. sendRedirect ("login_success.jsp") ; 
		   }
		   else {
			   response. sendRedirect ("login_failure.jsp") ; 
		   }
	}
}

到目前为止，项目的主要的功能文件已经完成。但是还要在web.xml中注册项目运行的欢迎文件以及servlet的注册。（关于web.xml文件的工作原理有机会在补上了）

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 http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
 <display-name>jspServletLoginTest</display-name>
 <servlet>
  <description>
  </description>
  <display-name>loginServlet</display-name>
  <servlet-name>loginServlet</servlet-name>
  <servlet-class>
  test.login.loginServlet</servlet-class>
 </servlet>
 <servlet-mapping>
  <servlet-name>loginServlet</servlet-name>
  <url-pattern>/loginServlet</url-pattern>
 </servlet-mapping>
 <!-- 通过如下的设置web project在tomcat服务器上运行的时候，可以首先启动和运行webcontent目录下面
 相应的页面，会根据welcome-file的list去检索 -->
 <welcome-file-list>
  <welcome-file>index.html</welcome-file>
  <welcome-file>index.jsp</welcome-file>
 </welcome-file-list>
</web-app>

如此就实现了jsp+servlet实现的用户登录功能。