我们在网站上登陆的时候，一般都会有一个选择框，记住用户名，这个功能的实现方式就是使用cookie实现的。
完成这个案例我们需要三个页面：
- LoginUIServlet 登录UI界面,只负责展示页面
- LoginServlet 提交之后的跳转页面,负责处理逻辑判断
- IndexServlet 登录成功之后的跳转页面
完成LoginUIServlet
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import com.itheima.cookie.CookieUtils;
public class LoginUIServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//设置响应类型和编码
response.setContentType("text/html;charset=UTF-8");
//获取输出流对象
PrintWriter out = response.getWriter();
Cookie[] cookies = request.getCookies();
Cookie cookie = CookieUtils.getCookie(cookies, "username");
String username = "";
String checked = "";
//如果cookie存在，那么设置用户名和复选框选择状态
if(cookie != null){
username = cookie.getValue();
checked = "checked = 'checked'";
}
//输出html页面
out.println("<html>");
out.println("<head>");
out.println("<title>登录页面</title>");
out.println("</head>");
out.println("<body>");
out.println("<form action='/web08/LoginServlet' method='post'>");
out.println("用户名:<input type='text' name='username' value='"+username+"'/>");
out.println("<br />");
out.println("密码:<input type='text' name='password' />");
out.println("<br />");
out.println("<input type='submit' value='登录' />");
out.println("<input type='checkbox' name='remember' value='1' "+checked+"/>记住用户名");
out.println("</form>");
out.println("</body>");
out.println("</html>");
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
完成LoginServlet
import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.http.Cookie;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//设置响应类型和编码
response.setContentType("text/html;charset=UTF-8");
//获取输出流
PrintWriter out = response.getWriter();
//获取表单中的数据
String username = request.getParameter("username");
String password = request.getParameter("password");
String remember = request.getParameter("remember");
//判断用户名和密码是否正确
if("zhangsan".equals(username) && "123456".equals(password)){
//用户名和密码正确,返回提示信息，跳转到首页
out.println("登陆成功！3秒后跳转到首页！");
response.setHeader("Refresh", "3;URL=/web08/IndexServlet");
//判断用户是否记住用户名
if("1".equals(remember)){
//用户需要记住用户名,则创建cookie对象保存用户名
Cookie c = new Cookie("username",username);
c.setMaxAge(Integer.MAX_VALUE);
response.addCookie(c);
}else{
//用户不需要记住用户名
Cookie c =new Cookie("username","");
c.setMaxAge(0);
response.addCookie(c);
}
}else{
//用户名或者密码错误
out.println("用户名或密码错误！3秒后跳转到登陆页面");
response.setHeader("Refresh", "3;URL=/web08/LoginUIServlet");
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
完成简单的首页IndexServlet
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 IndexServlet extends HttpServlet {
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//设置响应类型和编码
response.setContentType("text/html;charset=UTF-8");
//获取输出流对象
PrintWriter out = response.getWriter();
out.println("<h1>我是首页</h1>");
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// TODO Auto-generated method stub
doGet(request, response);
}
}
案例实现结果
登录页面
登录成功
再次打开登录界面
网友评论