我已用JSP形式并通过Servlet.I显示主页创建了一个简单登录应用程序还创建内部的servlet一个HashMap,其存储了几个用户名和passwords.When的用户输入用户名和密码它与那些本内相比地图和相应的消息是displayed.But这里的问题是HashMap的是用户点击登录按钮后,即Servlet程序开始up.I要初始化前手的地图,当与地图进行比较以往用户登录时进行初始化,应发生,而不是登录后初始化地图。一定要帮助我如何去做。 以下是我迄今所做如何在服务器启动时初始化哈希映射?
的Login.jsp
<%@ page language="java" contentType="text/html; charset=ISO-8859-1"
pageEncoding="ISO-8859-1"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>Login</title>
</head>
<body>
<center>
<b>LOGIN PAGE</b><br>
</center>
<form name="login" method="post" action="UserAuthentication">
<center>
USER NAME: <input type="text" name="username">
<br>
<br>
PASSWORD: <input type="password" name="password">
<br>
<br>
<input type="submit" value="LOGIN">
</center>
</form>
</body>
</html>
UserAuthentication.java
public class UserAuthentication extends HttpServlet{
public void doPost(HttpServletRequest request,HttpServletResponse response)
throws IOException{
String username = request.getParameter("username");
String password = request.getParameter("password");
PrintWriter out = response.getWriter();
Map<String,String>users = new HashMap<String,String>();
users.put("Sheetal", "sss");
users.put("Raj","rrr");
users.put("Anjali", "aaa");
users.put("Bhavya","bbb");
if(users.containsKey(username) && users.containsValue(password))
{
if(password.equals(users.get(username)))
{
out.println("<html>"+
"<body>"+
"Login Successful" + "<br>" +
"Welcome " + username + "<br>" +
"</body>" +
"</html>");
}
}
else
{
out.println("<html>"+
"<body>"+
"Login Unsuccessful" + "<br>" +
"Try again" + "<br>" +
"</body>" +
"</html>");
}
}
}
TIA
可以使用静态块.. – Prashant