这篇文章主要介绍java web如何实现自动登录功能，文中介绍的非常详细，具有一定的参考价值，感兴趣的小伙伴们一定要看完！
具体内容如下
主要思路就是：当用户访问网站的首页时，浏览器端会先检擦浏览器中存在的cookie中是否又登录的用户的用户名，如果有，则直接跳转至用户登录好的界面，如果没有，则重定向至登录界面，在服务器端创建该用户登录的cookie,响应时，将创建的cookie返回至浏览器端保存。
一、用户访问首页时检查cookie是否存在。
package ahpudong.com;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/index.do")
public class index extends HttpServlet {
public index() {
super();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
Cookie[] cookies=request.getCookies();
if(cookies!=null){
for(Cookie cookie:cookies){
String name=cookie.getName();
String value=cookie.getValue();
if("name".equals(name) && "chendong".equals(value)){
request.setAttribute(name, value);
request.getRequestDispatcher("user.view").forward(request, response);
return;
}
}
}
response.sendRedirect("login.jsp");
}
}二、确定用户登录的cookie不存在，在手动登录的过程中创建用户登录cookie。
package ahpudong.com;
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
@WebServlet("/login.do")
public class login extends HttpServlet {
public login() {
super();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
request.setCharacterEncoding("utf-8");
response.setCharacterEncoding("utf-8");
PrintWriter out = response.getWriter();
String name=request.getParameter("name");
String pwd=request.getParameter("pwd");
String login=request.getParameter("auto");
if("chendong".equals(name) && "123456".equals(pwd)){
if("on".equals(login)){
Cookie cookie=new Cookie("name","chendong");
cookie.setMaxAge(7*24*60*60);//有效期为一个星期
response.addCookie(cookie);
request.setAttribute("name",name);
request.getRequestDispatcher("user.view").forward(request, response);
}
}else{
response.sendRedirect("login.jsp");
}
}
}三、登录成功时的视图层
package ahpudong.com;
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;
@WebServlet("/user.view")
public class User extends HttpServlet {
public User() {
super();
}
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request,response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request,response);
}
public void processRequest(HttpServletRequest request,HttpServletResponse response)
throws ServletException, IOException{
response.setCharacterEncoding("utf-8");
PrintWriter out=response.getWriter();
String name=(String) request.getAttribute("name");
out.println("<!DOCTYPE HTML PUBLIC \"-//W3C//DTD HTML 4.01 Transitional//EN\">");
out.println("<HTML>");
out.println(" <HEAD><TITLE>A Servlet</TITLE></HEAD>");
out.println(" <BODY>");
out.println("<h2>"+"welcome "+name+" login"+"</h2>");
out.println(" </BODY>");
out.println("</HTML>");
out.flush();
out.close();
}
}以上是“java web如何实现自动登录功能”这篇文章的所有内容，感谢各位的阅读！希望分享的内容对大家有帮助，更多相关知识，欢迎关注亿速云行业资讯频道！
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