本文实例为大家分享了java实现登录案例的具体代码，供大家参考，具体内容如下
一、环境搭建
JDK1.8 + Tomcat1.8
二、目录结构
三、代码示例
3.1、fail.html页面
faill.html 亲， 你的用户名或密码输入有误！请重新输入!
返回登录页面
3.2、Login.htm页面
Login.html
3.3、IndexServlet.java
package cn.itcase.servlet;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class IndexServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// 设置编码格式
response.setContentType("text/html;charset=utf-8");// setContentType设置浏览器的编码格式
// 1.信息输出至浏览器
PrintWriter writer = response.getWriter();
String html = "";
// 2.得到session对象
HttpSession session = request.getSession(false);
// 2.1如果不存在session对象，登录不成功，跳转到登录页面
if (session == null) {
response.sendRedirect(request.getContextPath()
+ "/Login.html");
return;
}
// 2.2没有在session对象域中找到相应 session唯一标识ID 则登录不成功，跳转到登录页面
String loginName = (String) session.getAttribute("loginName");
if (loginName == null) {
response.sendRedirect(request.getContextPath() + "/Login.html");
return;
}
html = "欢迎回来，" + loginName + "，安全退出";
writer.write(html);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request, response);
}
}
3.4、LoginServlet.java
package cn.itcase.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class LoginServlet extends HttpServlet {
protected void doGet(HttpServletRequest request,
HttpServletResponse response) throws ServletException, IOException {
// 设置编码格式
request.setCharacterEncoding("utf-8");// setCharacterEncoding设置服务器的编码格式
// 1.根据参数名获取参数值
String userName = request.getParameter("UserName");
String userPwd = request.getParameter("UserPwd");
// 2.登录是否的逻辑判断
if("eric".equals(userName) && "123456".equals(userPwd)){
//2.1 登录成功
// 2.1.1创建session对象 用于保存数据
HttpSession session = request.getSession();
// 2.1.1把数据保存到session域中
session.setAttribute("loginName", userName); // session对象的唯一标识"loginName" 唯一标识名称 userName
//session.setMaxInactiveInterval(1*60*60*24*30); // session对象的有效时长 可以配置全局的有效时长
//2.1.3跳转到用户主页
response.sendRedirect(request.getContextPath() + "/IndexServlet"); //sendRedirect()重定向 getContextPath()请求路径
}else{
//2.2登录失败 请求重定向
response.sendRedirect(request.getContextPath() + "/fail.html");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setCharacterEncoding("utf-8");
doGet(request,response);
}
}
3.5、LogoutServlet.java
package cn.itcase.servlet;
import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class LogoutServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
HttpSession session = request.getSession(false);
if(session != null){
session.removeAttribute("loginName");
}
//返回登录页面
response.sendRedirect(request.getContextPath() + "/Login.html");
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doGet(request,response);
}
}
3.6、总结
知道了如何实现前端页面与后端的数据交互
疑惑：如果有多个用户难道还一个一个的去判断他存不存在么？
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持考高分网。
