我相信我的代码应该重定向到＆＃34;登录＆＃34; servlet的。它目前还没有使用任何验证，所以实际上它应该只是一次运行时将我重新引导到另一个servlet。我没有遇到404错误或500级错误，它只是将我重定向到我的Register servlet而不是登录
@WebServlet("/Register")
public class Register extends HttpServlet {
private static final long serialVersionUID = 1L;
public void init() throws ServletException {
// Create an array list of guest book HW1Users
ArrayList<HW1User> HW1Users = new ArrayList<HW1User>();
// Add the array list to the application scope
getServletContext().setAttribute("HW1Users", HW1Users);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE html>");
out.println("<html>");
out.println("<head>");
out.println("<meta charset=\"ISO-8859-1\">");
out.println("<title>Israel, Dylan - CS320stu32</title>");
out.println(
"<link rel=\"stylesheet\" href=\"https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css\">");
out.println("</head>");
out.println("<body>");
out.println("<form class=\"form-horizontal\">");
out.println("<div class=\"form-group\">");
out.println("<label for=\"name\" class=\"col-sm-2 control-label\">Name:</label>");
out.println("<div class=\"col-sm-10\">");
out.println("<input type=\"text\" class=\"form-control\" id=\"name\" placeholder=\"First and Last Name\">");
out.println("</div>");
out.println("</div>");
out.println("<div class=\"form-group\">");
out.println("<label for=\"inputEmail3\" class=\"col-sm-2 control-label\">Email:</label>");
out.println("<div class=\"col-sm-10\">");
out.println("<input type=\"email\" class=\"form-control\" id=\"inputEmail3\" placeholder=\"Enter Email\">");
out.println("</div>");
out.println("</div>");
out.println("<div class=\"form-group\">");
out.println("<label for=\"password1\" class=\"col-sm-2 control-label\">Password:</label>");
out.println("<div class=\"col-sm-10\">");
out.println("<input type=\"text\" class=\"form-control\" id=\"password1\" placeholder=\"Enter Password\">");
out.println("</div>");
out.println("</div>");
out.println("<div class=\"form-group\">");
out.println("<label for=\"password2\" class=\"col-sm-2 control-label\">Re-Enter Password:</label>");
out.println("<div class=\"col-sm-10\">");
out.println("<input type=\"text\" class=\"form-control\" id=\"password2\" placeholder=\"Re-Enter Password\">");
out.println("</div>");
out.println("</div>");
out.println("<div class=\"form-group\">");
out.println("<div class=\"col-sm-offset-2 col-sm-10\">");
out.println("<input type=\"submit\" value = \"Register\"/>");
out.println("</div>");
out.println("</form>");
// Grab a reference to the list of HW1Users
out.println("</body>");
out.println("</html>");
}
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String name = request.getParameter("name");
String password1 = request.getParameter("password1");
String password2 = request.getParameter("password2");
String email = request.getParameter("email");
ArrayList<HW1User> HW1Users = (ArrayList<HW1User>)getServletContext().getAttribute("HW1Users");
HW1Users.add(new HW1User(name,password1,password2,email));
// Add the new entry to the list
if(HW1Users!= null){
response.sendRedirect("/Login");
}
doGet(request, response);
}
}
在Kumar的回答之后，我将我的代码更新为：
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String name = request.getParameter("name");
String password1 = request.getParameter("password1");
String password2 = request.getParameter("password2");
String email = request.getParameter("email");
ArrayList<HW1User> HW1Users = (ArrayList<HW1User>)getServletContext().getAttribute("HW1Users");
HW1Users.add(new HW1User(name,password1,password2,email));
// Add the new entry to the list
if(HW1Users!= null){
response.sendRedirect("/Login");
return; // returns causing response stream to be committed only once
}
doGet(request, response); // This will treat your request as a get request only if HW1Users is null
}
这是我的登录Servlet代码，表明它不会重定向任何内容。
@WebServlet("/Login")
public class Login extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();
out.println("<!DOCTYPE html>");
out.println("<html>");
out.println("<head>");
out.println(" <meta charset=\"UTF-8\">");
out.println(" <title>Sessions Login</title>");
out.println(" <link rel=\"stylesheet\" href=\"https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css\">");
out.println("</head>");
out.println("<body>");
out.println("<div class=\"container\">");
String error = (String) request.getAttribute("error");
if (error != null)
out.println("<p class=\"text-danger lead\">" + error + "</p>");
// Page-Specific Content
out.println("<form action=\"Login\" method=\"post\" >");
out.println(" Username: <input type=\"text\" name=\"username\" /> <br />");
out.println(" Password: <input type=\"password\" name=\"password\" /> <br />");
out.println(" <input type=\"submit\" value=\"Login\" />");
out.println("</form>");
out.println("</div>");
out.println("</body>");
out.println("</html> ");
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String username = request.getParameter("username");
String password = request.getParameter("password");
if (username != null && username.equals("albert")
&& password != null && password.equals("1!") ){
// Create a Session Variable named Username
HttpSession session = request.getSession();
session.setAttribute("username", "Albert F. Cervantes");
// Redirect to the Member's Only page
response.sendRedirect("Members");
}
else {
request.setAttribute("error", "Invalid Username and/or Password");
doGet(request, response);
}
}
}
答案 0 :(得分：2)
您的回复将通过response.sendRedirect("/Login");和doGet(request, response);提交两次。
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String name = request.getParameter("name");
String password1 = request.getParameter("password1");
String password2 = request.getParameter("password2");
String email = request.getParameter("email");
ArrayList<HW1User> HW1Users = (ArrayList<HW1User>)getServletContext().getAttribute("HW1Users");
HW1Users.add(new HW1User(name,password1,password2,email));
// Add the new entry to the list
if(HW1Users!= null){
response.sendRedirect("/Login");
return; // returns causing response stream to be committed only once
}
doGet(request, response); // This will treat your request as a get request only if HW1Users is null
}