Cookie实现记住登录密码，用户可以自由选择是否记住密码，或者用户之前选择记住了，但是某一次又不想记住了，需要将之前对应的Cookie删除掉
Cookie相当于map 也是键值对的形式，但是并不相同
response.addCookie(Cookie对象名)才会生效;
表单提交用的get 方便地址栏查看数据变化，
登录Servlet：
package ni.jun.yang.servlet; 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("/LoginServlet1") public class LoginServlet1 extends HttpServlet { private static final long serialVersionUID = 1L; public LoginServlet1() { } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setCharacterEncoding("utf-8"); PrintWriter out = response.getWriter(); Cookie [] cookies = request.getCookies(); //声明用户名和密码为空字符串 String uName = ""; String uPsw = ""; //获取根据名字获取对应的cookie 的值 if(cookies!=null){ for(Cookie x : cookies){ if(x.getName().equals("userName")){ uName = x.getValue(); }else if(x.getName().equals("userPsw")){ uPsw = x.getValue(); } } } out.println("<html><head><meta charset='utf-8'><title>Cookie</title>"); out.println("</head>"); out.println("<body>"); // input 标签的value 为声明的字符串，没有cookie 就是空字符串，有cookie就是获取到的用户名和密码 out.println("<form action='ResultServlet' method='get'>"); out.println("用户名：<input type='text' name='userName' value=" + uName + ">"); out.println("密码：<input type='password' name='userPsw' value=" + uPsw + ">"); out.println("用户名：<input type='checkbox' name='remember' "); //如果用户名和密码都获取到内容了，就将复选框默认选中记住密码，如果没有cookie，则不会默认选中，需要手动选择 if (uName != "" && uPsw != "") { out.println("checked='checked'"); } out.println(" >记住密码"); out.println("<input type='submit' value='登录'>"); out.println("</form"); out.println("</body>"); out.println("</html>"); } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }
数据处理代码：
package ni.jun.yang.servlet; import java.io.IOException; 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("/ResultServlet") public class ResultServlet extends HttpServlet { private static final long serialVersionUID = 1L; public ResultServlet() { } protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8"); //获取用户名和密码以及复选框是否选中 String userName = request.getParameter("userName"); String userPsw = request.getParameter("userPsw"); String remember = request.getParameter("remember"); // remember !=null 复选框被选中，需要设置cookie记住用户明和密码； if(remember != null){ //没有连接数据库，给一个设定的用户和密码 if(userName.equals("lisi") && userPsw.equals("123")){ //成功匹配，说明登录成功，设置cookie Cookie cName = new Cookie("userName", userName); Cookie cPsw = new Cookie("userPsw", userPsw); cName.setMaxAge(300); cPsw.setMaxAge(300); response.addCookie(cName); response.addCookie(cPsw); } // remember =null 没有选中记住密码，或以前记住了密码，但是后来登录时取消了记住密码，则将对应的cookie清除 }else{ Cookie [] cookies = request.getCookies(); if(cookies != null){ for(Cookie x : cookies){ if(x.getName().equals("userName")){ //设置时间0 清除cookie x.setMaxAge(0); response.addCookie(x); }else if(x.getName().equals("userPsw")){ x.setMaxAge(0); response.addCookie(x); } } } } } protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doGet(request, response); } }