package org.springframework.web.servlet;public interface HandlerInterceptor {boolean preHandle(HttpServletRequest request, HttpServletResponse response,Object handler)throws Exception;void postHandle(HttpServletRequest request, HttpServletResponse response,Object handler, ModelAndView modelAndView)throws Exception;void afterCompletion(HttpServletRequest request, HttpServletResponse response,Object handler, Exception ex)throws Exception;
}

preHandle: 预处理回调方法, 在controller层之前调用.返回值: true 表示继续流程(如调用下一个拦截器或处理器).false 表示流程中断, 不会继续调用其他的拦截器或处理器.
postHandle: 后处理回调方法, 在controller层之后调用(但在渲染视图之前), 我们可以通过modelAndView(模型和视图对象)对模型数据进行处理或对视图进行处理, modelAndView也可能为null.
afterCompletion: 整个请求处理完毕回调方法, 即在视图渲染完毕时回调, 类似于try-catch-finally中的finally.当然前提是该拦截器的preHandle返回true.

    <mvc:interceptors><!-- 使用bean定义一个Interceptor，直接定义在mvc:interceptors根下面的Interceptor将拦截所有的请求 --><bean class="com.host.app.web.interceptor.AllInterceptor"/><mvc:interceptor><!-- 定义在mvc:interceptor下面的表示是对特定的请求才进行拦截的 --><mvc:mapping path="/**"/><bean class="xxx.xxx.XXXInterceptor"/></mvc:interceptor><mvc:interceptor><mvc:mapping path="/**"/><bean class="yyy.yyy.YYYInterceptor"/></mvc:interceptor></mvc:interceptors>

@Controller
@RequestMapping("/")
public class HelloController {@RequestMapping(value="/login", method={RequestMethod.POST, RequestMethod.GET})@ResponseBodypublic String login(@RequestParam("username") String username,@RequestParam("password") String password,HttpSession session) {session.setAttribute("user", "...");return "ok";}@RequestMapping(value="/echo", method={RequestMethod.POST, RequestMethod.GET})public ModelAndView echo(@RequestParam("message") String message,HttpSession session, HttpServletResponse response) {ModelAndView mav = new ModelAndView();// *) 判断是否已经登陆Object obj = session.getAttribute("user");if ( obj == null ) {try {response.sendRedirect("/html/login.html");} catch (IOException e) {e.printStackTrace();}}mav.addObject("message", message);mav.setViewName("/echo");return mav;}}

    @Componentpublic class UserVerifyIntercptor extends HandlerInterceptorAdapter {private String[] allowUrls = new String[] {// *) 用户登陆相关的接口"/login",};@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {String uri = request.getRequestURI();for ( String allowUri : allowUrls ) {if ( allowUri.equalsIgnoreCase(uri) ) {return true;}}// *) 判断是否已经登陆HttpSession session = request.getSession();Object obj = session.getAttribute("user");if ( obj == null ) {response.sendRedirect("/html/login.html");return false;}// *)return true;}}

        <!-- 拦截器列表 --><mvc:interceptors><!-- 用户登陆的验证拦截器 --><mvc:interceptor><mvc:mapping path="/**" /><mvc:exclude-mapping path="/html/**" /><bean class="com.springapp.mvc.interceptor.UserVerifyIntercptor" /></mvc:interceptor></mvc:interceptors>

    @RequestMapping(value="/echo", method={RequestMethod.POST, RequestMethod.GET})public ModelAndView echo(@RequestParam("message") String message) {ModelAndView mav = new ModelAndView();mav.addObject("message", message);mav.setViewName("/echo");return mav;}

　　@RequestMapping(value="/sample", method={RequestMethod.GET, RequestMethod.POST})@ResponseBodypublic String sample(@RequestParam("message") String message) {// *) 记录请求参数RestLoggerUtility.noticeLog("[params: {message:%s}]", message);// serviceA.call(),// 记录调用的子过程/子服务, 结果是什么, 总共耗时多少等等RestLoggerUtility.noticeLog("[serviceA.call, params: xxx, result: xxx, consume xs]");// serviceB.call(),// 记录调用的子过程/子服务, 结果是什么, 总共耗时多少等等RestLoggerUtility.noticeLog("[serviceB.call, params: xxx, result: xxx, consume xs]");// *) 记录最终的响应结果RestLoggerUtility.noticeLog("[response: ok]");return "ok";}

[params: {message:10}][serviceA.call, params: xxx, result: xxx, consume xs][serviceB.call, params: xxx, result: xxx, consume xs][response: ok]

　　public class RestLoggerUtility {private static final Logger restLogger = LoggerFactory.getLogger("rest");public static final ThreadLocal<StringBuilder> threadLocals = new ThreadLocal<StringBuilder>();public static void beforeInvoke() {StringBuilder sb = threadLocals.get();if (sb == null) {sb = new StringBuilder();threadLocals.set(sb);}sb.delete(0, sb.length());}public static void returnInvoke() {StringBuilder sb = threadLocals.get();if (sb != null && sb.length() > 0) {restLogger.info(sb.toString());}}public static void throwableInvoke(String fmt, Object... args) {StringBuilder sb = threadLocals.get();if (sb != null) {restLogger.info(sb.toString() + " " + String.format(fmt, args));}}public static void noticeLog(String fmt, Object... args) {StringBuilder sb = threadLocals.get();if (sb != null) {// *) 对长度进行限定if ( sb.length() < 1024 ) {sb.append(String.format(fmt, args));}}}}

　　public class RestLoggerInterceptor extends HandlerInterceptorAdapter {private static final Logger restLogger = LoggerFactory.getLogger("rest");@Overridepublic boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {// *) 日志准备RestLoggerUtility.beforeInvoke();return super.preHandle(request, response, handler);}@Overridepublic void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {super.postHandle(request, response, handler, modelAndView);}@Overridepublic void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {super.afterCompletion(request, response, handler, ex);// *) 进行日志的刷新RestLoggerUtility.returnInvoke();}}

    <!-- 拦截器列表 --><mvc:interceptors><!-- 日志拦截器, 更好地记录整个请求过程 --><mvc:interceptor><mvc:mapping path="/**"/><mvc:exclude-mapping path="/html/**" /><bean class="com.springapp.mvc.interceptor.RestLoggerInterceptor" /></mvc:interceptor><mvc:interceptor><mvc:mapping path="/**" /><mvc:exclude-mapping path="/html/**" /><bean class="xxx.xxx.XXXIntercptor" /></mvc:interceptor></mvc:interceptors>

    @ControllerAdvicepublic class RestApiControlAdvice {private static final Logger restLogger = LoggerFactory.getLogger("rest");@ExceptionHandler(value=Exception.class)@ResponseBodypublic String handle(Exception e) {restLogger.warn("exception", e);RestLoggerUtility.throwableInvoke("[exception: msg:%s]", e.getMessage());return "error";}}