这是我第一次使用Java的servlet(和JSP(编程，现在我有点怀疑。想象一下，我正在建立一个有登录页面(假设是起始页面(和购物页面("第二个"页面(的网店。我的servlet包含用于识别用户的代码，如果用户是正确的，servlet应该显示购物目录。我的答案是，做这件事的最佳方法是什么？这是我的servlet代码(doGet(：
nb：用户名和密码来自登录页面。。。
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.getWriter().append("Served at: ").append(request.getContextPath());
response.setContentType("text/html");
PrintWriter out = response.getWriter();
String userName = request.getParameter("userName");
String password = request.getParameter("password");
out.println("<html>");
out.println("<body bgcolor = 'green'>");
out.println("<br>" + "Hello " + " " + userName + "<br> LOGGED IN!" + "<br>");
out.println("Your password is : " + " " + password + "<br>");
if(userName.equals("some_correct_user")) {
out.println("<p>Login correct </p>");
response.sendRedirect("/FirstServletExercise/shoppingPage.html");
}
else {
out.println("<p>Access denied</p>");
}
我知道这很简单，但这只是一个概念：使用"；sendRedirect"；显示另一个不同的页面，或者我必须升级第一个页面的内容？我该怎么做？希望我解释得很好。谢谢
我使用的是Jetty-11 Server独立/嵌入式模式。下面是登录Servlet的样子。
import java.io.IOException;
import java.util.Map;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import jakarta.servlet.ServletException;
import jakarta.servlet.http.Cookie;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;
public class LoginServlet extends HttpServlet {
private Logger log = LoggerFactory.getLogger(LoginServlet.class);
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
log.debug("LoginServlet {} userPrincipal: {}", req.getServletPath(), req.getUserPrincipal());
Map<String, String[]> p = req.getParameterMap();
p.forEach((k, v) -> {
log.debug("{} {}", k, v);
});
String un = (p.get("j_username") != null) ? p.get("j_username")[0] : null;
String up = (p.get("j_password") != null) ? p.get("j_password")[0] : null;
try {
if (un != null && up != null) {
req.logout();
req.login(un, up);
}
} catch (Exception e) {
log.error("AuthenticationException: ", e);
}
log.debug("{} userPrincipal: {}", req.getServletPath(), req.getUserPrincipal());
boolean isAuth = (req.getUserPrincipal() == null) ? false : true;
log.debug("isAuth: {}", isAuth);
resp.setContentType("text/html");
if (isAuth) {
/** Session Management */
HttpSession session = req.getSession();
session.setAttribute("user", req.getUserPrincipal().getName());
// setting session to expiry in 30 mins
session.setMaxInactiveInterval(30 * 60);
log.debug("sessionId: {} ", req.getSession().getId());
/** Cookie Management */
Cookie loginCookie = new Cookie("user", req.getUserPrincipal().getName());
loginCookie.setMaxAge(30 * 60);
resp.addCookie(loginCookie);
/** Login Success - so display the Home Page */
resp.sendRedirect("./index.html");
} else {
Cookie loginCookie = new Cookie("user", "unknownUser");
loginCookie.setMaxAge(0);
loginCookie.setPath("/");
resp.addCookie(loginCookie);
req.getRequestDispatcher("./login.html").forward(req, resp);
}
}
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
doGet(req, resp);
}
}