public class LoginInterceptor implements Interceptor {
	private static Logger logger = Logger.getLogger(LoginInterceptor.class);

	@Override
	public void intercept(Invocation inv) {
		BaseController controller = (BaseController) inv.getController();
		String lastRequestURL = controller.getRequest().getRequestURL().toString();

		logger.info("请求地址：" + lastRequestURL);

		Members loginMem = controller.getSessionAttr("username");

		// 用户如果没有登录，那么就跳转到登录页面
		if (loginMem == null || loginMem.equals("")) {

			try {
				controller.redirect("/mem/initLogin?forwardURL=" + URLEncoder.encode(lastRequestURL, "UTF-8"));
			} catch (UnsupportedEncodingException e) {
				logger.error(e.getMessage());
			}

		} else {
			inv.invoke();
		}
	}
}

注意：

1. 全局拦截器可参照jfinal官方文档添加到config类中。
2. 如果用户没有登录，则跳转到登录页，并且将当前的url路径作为参数传递给form表单，至于form表单怎么获取，请看下个小节。

<form class="pop_login_form" action="${ctx}/mem/login?callbackType=forward" method="post"
			οnsubmit="return validateCallback(this, ajaxDone)">

注意：

@Clear({LoginInterceptor.class})
	public void login() throws UnsupportedEncodingException {
		logger.info("进行会员登录操作...");

		// 获取用户名
		String name = getPara("username");
		// 获取密码
		String password = getPara("password");

		Members mem = Members.me.getMemByUsername(name);

		if (mem != null) {// 用户不存在
			// 密码不匹配
			if (!mem.getStr("password").equals(CipherUtils.generatePassword(password))) {
				ajaxDoneError("密码不正确！");
			} else {
				// 保存session
				setSessionAttr("username", mem);
				
				String forwardURL = getPara("forwardURL");
				
				if (forwardURL == null || forwardURL.equals("")) {
					forwardURL = "/";
				} else {
					forwardURL = URLDecoder.decode(forwardURL, "UTF-8");
				}

				ajaxDoneSuccess("登录成功！", forwardURL);
			}

		} else {
			ajaxDoneError("用户不存在！");
		}
	}

public void ajaxDoneSuccess(String message, String forwardURL) {
		ajaxDone(200, message, forwardURL);
	}
protected void ajaxDone(int statusCode, String message, String forwardURL) {
	// 回调类型
		if (getAttr("callbackType") == null) {
			String callbackType = getPara("callbackType");
			if (callbackType != null && !callbackType.equals("")) {
				setAttr("callbackType", callbackType);

				if (callbackType.equals("forward") || callbackType.equals("closeCurrentThenForward")) {
					String contextPath = getRequest().getContextPath();
					
					if (forwardURL.indexOf(contextPath) == -1) {
						forwardURL = contextPath + forwardURL;
					}
					
					setAttr("forwardURL", forwardURL);
				}
			}
		}

		renderJson();
}	

function ajaxDone(json) {
	YUNM.ajaxDone(json);
	if (json[YUNM.keys.statusCode] == YUNM.statusCode.ok || json[YUNM.keys.statusCode] == YUNM.statusCode.info) {
if ("forward" == json.callbackType) {
			if (json.forwardURL) {
				location.href = json.forwardURL;
			}
}

跳转到上一个页面。