spring security ajax示例
a. applicationContext-security.xml

		<form-login login-page="/login" default-target-url="/frames"
			login-processing-url="/securitycheck" always-use-default-target="true" />
		<session-management invalid-session-url="/logintimeout" />

b. index.ftl -- freemarker template

<#macro msg key> ${rc.getMessage(key)} </#macro>
		<script src="${rc.getContextPath()}/static/scripts/jquery-1.6.2.min.js" type="text/javascript"></script>
		<script src="${rc.getContextPath()}/static/scripts/jquery.easyui.min.js" type="text/javascript"></script>
		<script src="${rc.getContextPath()}/static/scripts/jquery.validate.min.js" type="text/javascript"></script>

				<form id="loginForm" action="${rc.getContextPath()}/securitycheck" method="post">
					<table align="center" style="border-spacing: 5px">
						<tr>
							<td colspan="2" style="color:#FF0000" align="left">
								<#if errors><@msg key="page.login.fail"/></#if>
							</td>
						</tr>
						<tr>
							<td align="right"><@msg key="page.login.label.username"/>:</td>
							<td><input type='text' name='j_username' class="required" /></td>
						</tr>
						<tr>
							<td align="right"><@msg key="page.login.label.password"/>:</td>
							<td><input type='password' name='j_password' class="required" /></td>
						</tr>
						<tr style="display:none">
							<td><input type="checkbox" name="_spring_security_remember_me" />
							</td>
							<td>Remember me for 2 weeks</td>
						</tr>
						<tr>
							<td colspan='2' align="right"><input value='<@msg key="page.login.button.submit"/>' type="submit" class="btnorange" /></td>
						</tr>
					</table>
				</form>


	<script>
		$('#loginForm').form({  
		    onSubmit: function(){  
		        var valid = $('#loginForm').valid();
		        if ( ! valid ) {
			        // return false to prevent submit;
		        	return false;
		        }
		        return true;  
		    },  
		    success:function(data){
		    	if ( data == null || data.length < 2 ) {
		    	} else {
	    			$.get('${rc.getContextPath()}/frames', function(data) {
	    				$('body').empty().html(data).find('.easyui-layout').layout();
	    			});
		    	}
		    }  
		});
	</script>

c. LoginController.java

	@RequestMapping("/login")
	public String index(Model model, HttpServletRequest request, HttpServletResponse response) {
		AuthenticationException ae = (AuthenticationException) request.getSession().getAttribute(AUTHENTICATION_EXCEPTION);
		model.addAttribute("errors", false);
		if (ae != null) {
			model.addAttribute("errors", true);
		}
		return "/index";
	}

	@RequestMapping("/frames")
	public String frames(Model model, HttpServletRequest request) {
		logger.trace("redirect to page frames.");
		String userName = SpringSecurityContext.getUsername();
		model.addAttribute("name", userName);
		SecUser user = userManager.getUserByName(userName);
		if (user != null) {
			WebUtils.setSessionAttribute(request, GlobalConstant.SESSION_USER, user);
		}
		return "/frames";
	}