response.setContentType("text/html;charset=UTF-8");
		out = response.getWriter();
		request.setCharacterEncoding("UTF-8");
                         HttpSession session = request.getSession();

<%@ page contentType="text/html; charset=utf-8"%>

<%@ page contentType="text/html;  Charset=UTF-8" language="java" %>
...
Username:
<% if (session.getAttribute("username")!= null ){
	username = session.getAttribute("username").toString();	
}%>
<input type="text" name="username" value="<%=username%>"/>

response.setContentType("text/html;charset=UTF-8");
out = response.getWriter();
request.setCharacterEncoding("UTF-8");
HttpSession session = request.getSession();

username = request.getParameter("username");

session.setAttribute("username", username);
...
 if (error!= 0 ){
response.sendRedirect(response.encodeRedirectURL("./xxx.jsp"));
}