java中servlet实现登录验证的方法

2019-11-26 16:07:02

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package com.ncu;
import java.io.PrintWriter;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class login extends HttpServlet{
public void doGet(HttpServletRequest req,HttpServletResponse res){
  try{
   //res.setCharacterEncoding("utf-8");
   res.setContentType("text/html;charset=gbk");
   PrintWriter pw=res.getWriter();
   //返回登录界面
   pw.print("<html>");
   pw.print("<head>");
   pw.print("<title>登录界面</title></head>");
   pw.print("<body>");
   pw.print("<h1>用户登录界面</h1>");
   pw.print("<form action='loginpro' method=post>");
   pw.print("用户名：<input type=text name=userName><br>");
   pw.print("密码：<input type=password name=Pwd><br>");
   pw.print("<input type=submit value=submit>");
   pw.print("</body></html>");


  }catch(Exception e)
  {
   e.printStackTrace();
  }
}
}

LoginPro.java:

复制代码代码如下:

package com.ncu;
import java.io.PrintWriter;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginPro extends HttpServlet{
public void doPost(HttpServletRequest req,HttpServletResponse res){
  try{
   String user=req.getParameter("userName");
   String pwd=req.getParameter("Pwd");
   if(user==null){
    user="";
   }
   if(pwd==null)
   {
    pwd="";
   }
   if(user.equals("nicolas")&&pwd.equals("nicolas")){
    //用户和密码合法
    //res.sendRedirect("wel");
//    res.setCharacterEncoding("gbk");
//    PrintWriter pw=res.getWriter();
//    pw.print("恭喜你，登录成功！！");
    res.sendRedirect("welcome");

   }
   else{
    //不合法进行跳转

    res.sendRedirect("login");//跳转到登录界面
   }


  }catch(Exception e)
  {
   e.printStackTrace();
  }
}
}

Welcome.java:

复制代码代码如下:

package com.ncu;
import java.io.PrintWriter;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class Welcome extends HttpServlet{
public void doGet(HttpServletRequest req,HttpServletResponse res){
  try{
   res.setCharacterEncoding("gbk");
   PrintWriter pw=res.getWriter();
   pw.print("welcome，您好");

  }catch(Exception e)
  {
   e.printStackTrace();
  }
}
}

web.xml

复制代码代码如下:

<?xml version="1.0" encoding="UTF-8"?>
<web-app version="3.0"
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_3_0.xsd">
<display-name></display-name>
<welcome-file-list>
    <welcome-file>index.jsp</welcome-file>
</welcome-file-list>
<servlet>

<servlet-name>hello</servlet-name>

<servlet-class>com.ncu.Hello</servlet-class>

</servlet>
   <servlet-mapping>
   
     <servlet-name>hello</servlet-name>


<url-pattern>/nicolas</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>helloservlet</servlet-name>
<servlet-class>com.ncu.HelloServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>helloservlet</servlet-name>
<url-pattern>/helloservlet</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>helloHttpServlet</servlet-name>
<servlet-class>com.ncu.helloHttpServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>helloHttpServlet</servlet-name>
<url-pattern>/helloHttpServlet</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>login</servlet-name>
<servlet-class>com.ncu.login</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>login</servlet-name>
<url-pattern>/login</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>loginpro</servlet-name>
<servlet-class>com.ncu.LoginPro</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>loginpro</servlet-name>
<url-pattern>/loginpro</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>welcome</servlet-name>
<servlet-class>com.ncu.Welcome</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>welcome</servlet-name>
<url-pattern>/welcome</url-pattern>
</servlet-mapping>
</web-app>

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