总结：
JavaWeb 利用Cookie 存储在本地用户名和密码，设置Cookie的生存时间。
两个页面，一个登陆页面，一个登陆后的页面，在登陆页面选择是否保存Cookie(保存Cookie，下次自动填充用户名和密码)，提价后根据用户的选择在第二个页面进行Cookie的设置。
登陆页面：
1 import java.io.IOException; 2 import java.io.PrintWriter; 3 4 import javax.servlet.ServletException; 5 import javax.servlet.annotation.WebServlet; 6 import javax.servlet.http.Cookie; 7 import javax.servlet.http.HttpServlet; 8 import javax.servlet.http.HttpServletRequest; 9 import javax.servlet.http.HttpServletResponse; 10 11 @WebServlet("/JavaWebcs") 12 public class JavaWebcs extends HttpServlet { 13 private static final long serialVersionUID = 1L; 14 15 public JavaWebcs() { 16 super(); 17 } 18 19 protected void doGet(HttpServletRequest request, 20 HttpServletResponse response) throws ServletException, IOException { 21 response.setContentType("text/html;charset=utf-8"); 22 PrintWriter out = response.getWriter(); 23 String userName = ""; 24 String password = ""; 25 String ischecked = ""; 26 Cookie[] list = request.getCookies(); 27 if (list != null && list.length > 0) { 28 ischecked = "checked"; 29 for (int i = 0; i < list.length; i++) { 30 if (list[i].getName().equals("username")) 31 userName = list[i].getValue(); 32 if (list[i].getName().equals("password")) 33 password = list[i].getValue(); 34 } 35 } 36 out.println("<html><head><meta charset='utf-8'><title>Login!</title></head></body>" 37 + "<form action='yz' method='POST'>user name:<input name='username' type='text' value=" 38 + userName 39 + "><br />user pwd:<input name='password' type='password' value=" 40 + password 41 + "><br />save user info<input name='check' type='checkbox' value='Yes'" 42 + ischecked 43 + "><br /><input type='button' onclick='submit()' value='submit'></form>" 44 + "</body></html>"); 45 } 46 47 protected void doPost(HttpServletRequest request, 48 HttpServletResponse response) throws ServletException, IOException { 49 doGet(request, response); 50 } 51 52 }
跳转到的页面（设置Cookie）：hello username
1 import java.io.IOException; 2 import java.io.PrintWriter; 3 4 import javax.servlet.ServletException; 5 import javax.servlet.annotation.WebServlet; 6 import javax.servlet.http.Cookie; 7 import javax.servlet.http.HttpServlet; 8 import javax.servlet.http.HttpServletRequest; 9 import javax.servlet.http.HttpServletResponse; 10 11 @WebServlet("/yz") 12 public class yz extends HttpServlet { 13 private static final long serialVersionUID = 1L; 14 15 public yz() { 16 super(); 17 } 18 19 protected void doGet(HttpServletRequest request, 20 HttpServletResponse response) throws ServletException, IOException { 21 PrintWriter out = response.getWriter(); 22 String username = request.getParameter("username"); 23 String password = request.getParameter("password"); 24 Cookie userName = new Cookie("username", username); 25 Cookie passWord = new Cookie("password", password); 26 if (request.getParameter("check") != null 27 && request.getParameter("check").equals("Yes")) { 28 userName.setMaxAge(7 * 24 * 60 * 60); 29 passWord.setMaxAge(7 * 24 * 60 * 60); 30 } else { 31 userName.setMaxAge(0); 32 passWord.setMaxAge(0); 33 } 34 response.addCookie(userName); 35 response.addCookie(passWord); 36 out.println("hello " + username); 37 38 } 39 40 protected void doPost(HttpServletRequest request, 41 HttpServletResponse response) throws ServletException, IOException { 42 doGet(request, response); 43 } 44 45 }