Login to add Token dynamic password verification

1. For the new class ValidateToken.java,
see the attachment ValidateToken.java
2. Add a judgment statement in the servlet
if(!ValidateToken.isTokenStringValid(request.getParameter(ValidateToken.TOKEN_STRING_NAME),
        request.getSession()))
    {
    throw new AdminLoginException(" Login failed");
}
else
{
    //Code body...
}
3. Add a hidden field (import class)
in 3.jsp <%@ page import = "com.huawei.colorring.utilities.ValidateToken"%>

<input type= "hidden" name="<%=ValidateToken.TOKEN_STRING_NAME%>"
value="<%=ValidateToken.getTokenString(request.getSession(true))%>">