拦截器求助

response.setContentType("text/html");
response.setCharacterEncoding("utf-8");
PrintWriter out = response.getWriter();
StringBuilder str = new StringBuilder();
str.append("<script type=\"text/javascript\">");
str.append(" alert(\"请先登录！\"); ");
//str.append(" window.location.href = \"login.jsp\"; ");
str.append("</script>");
System.out.println(str.toString());
out.write(str.toString());
out.close();
return false;
用的ssm框架，拦截器继承spring的HandlerInterceptorAdapter
为什么没有返回提示 ， 求解