servlet登入验证

迈不过友情╰ 2022-06-13 02:49 152阅读 0赞

### 流程 ###

从登入界面输入用户名admin密码123则登入成功

--------------------

登入界面的servlet

package com.cyh.web;
    
    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 Login extends HttpServlet{
            protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
                response.setContentType("text/html;charset=utf-8");
                PrintWriter out = response.getWriter();
                out.println("用户登入");
                out.println("<form action='/M3/b' method='post'>");
                out.println("用户名:<input type='text' name='username'/><br />");
                out.println("密码:<input type='password' name='userpass'/><br />");
                out.println("<input type='submit' value='登入'/><br />");
                out.println("</form>");
            }
            protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
    
            }
    }

点击登入就会将表单的数据提交到/M3/b的servlet中，处理用户名和密码是否正确

### 处理的serlvet ###

package com.cyh.web2;
    
    import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class Logincl extends HttpServlet { 
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            response.setContentType("text/html; charset=utf-8");
            String s1 = request.getParameter("username");
            String s2 = request.getParameter("userpass");
            System.out.println("用户名"+s1);
            System.out.println("密码"+s2);
    
            //
            if("admin".equals(s1) && "123".equals(s2)){
                //登入成功，跳到主界面
                //sendRedirect写法 /web应用名/servlet的url
                response.sendRedirect("/M3/c");
            }else{
                //登入失败
                response.sendRedirect("/M3/a");
            }
        }
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            this.doGet(request, response);
        }
    }

验证密码成功就会跳转到/M3/c的servlet中

import java.io.IOException;
    import java.io.PrintWriter;
    
    import javax.servlet.ServletException;
    import javax.servlet.annotation.WebServlet;
    import javax.servlet.http.HttpServlet;
    import javax.servlet.http.HttpServletRequest;
    import javax.servlet.http.HttpServletResponse;
    
    public class MainFrame extends HttpServlet { 
    
        protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
            response.setContentType("text/html; charset=utf-8");
            PrintWriter out = response.getWriter();
            System.out.println("yes");
            out.println("<h1>主界面</h1>");
        }
        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        }
    }

web.xml配置文件

<servlet>
        <servlet-name>servlet</servlet-name>
        <servlet-class>com.cyh.web.Login</servlet-class>
      </servlet>
      <servlet-mapping>
        <servlet-name>servlet</servlet-name>
        <url-pattern>/a</url-pattern>
      </servlet-mapping>
    
      <servlet>
        <servlet-name>logincl</servlet-name>
        <servlet-class>com.cyh.web2.Logincl</servlet-class>
      </servlet>
      <servlet-mapping>
        <servlet-name>logincl</servlet-name>
        <url-pattern>/b</url-pattern>
      </servlet-mapping>
    
        <servlet>
        <servlet-name>MainFrame</servlet-name>
        <servlet-class>com.cyh.web2.MainFrame</servlet-class>
      </servlet>
      <servlet-mapping>
        <servlet-name>MainFrame</servlet-name>
        <url-pattern>/c</url-pattern>
      </servlet-mapping>

### 知识扩充 ###

有中文需要转码response.setContentType(“text/html; charset=utf-8”);  
通过request.getParameter(标签名); 来获取表单中的相应数据