Spring MVC 拦截器 interceptors

Spring 拦截器

spring-mvc.xml文件配置

<mvc:interceptors>
		<mvc:interceptor>
			<mvc:mapping path="/web/*" /><!-- 拦截路径 -->
			<bean class="com.mvc.UrlInteceptor"></bean>
		</mvc:interceptor>
</mvc:interceptors>

拦截器回调函数实现

public class UrlInteceptor extends HandlerInterceptorAdapter {
    /**
     * 该方法在业务处理器处理请求之前被调用
     */
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response,
            Object handler) throws Exception {
        return true;
    }
    
    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response,
            Object handler, ModelAndView modelAndView) throws Exception {
    }
    /**
     * 
     * 该方法在业务处理器处理请求之后被调用
     * 
     */
    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response,
            Object handler, Exception ex) throws Exception {
    }
}

一个简单的登陆拦截器

package com.alibaba.interceptor;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.handler.HandlerInterceptorAdapter;

import com.alibaba.util.RequestUtil;


/**
 * @author tfj
 * 2014-8-1
 */
public class CommonInterceptor extends HandlerInterceptorAdapter{
	private final Logger log = LoggerFactory.getLogger(CommonInterceptor.class);
	public static final String LAST_PAGE = "com.alibaba.lastPage";
	/*
	 * 利用正则映射到需要拦截的路径    
	 
    private String mappingURL;
    
    public void setMappingURL(String mappingURL) {    
               this.mappingURL = mappingURL;    
    }   
  */
    /** 
     * 在业务处理器处理请求之前被调用 
     * 如果返回false 
     *     从当前的拦截器往回执行所有拦截器的afterCompletion(),再退出拦截器链
     * 如果返回true 
     *    执行下一个拦截器,直到所有的拦截器都执行完毕 
     *    再执行被拦截的Controller 
     *    然后进入拦截器链, 
     *    从最后一个拦截器往回执行所有的postHandle() 
     *    接着再从最后一个拦截器往回执行所有的afterCompletion() 
     */  
    @Override  
    public boolean preHandle(HttpServletRequest request,  
            HttpServletResponse response, Object handler) throws Exception {  
    	if ("GET".equalsIgnoreCase(request.getMethod())) {
    		RequestUtil.saveRequest();
        }
        log.info("==============执行顺序: 1、preHandle================");  
		String requestUri = request.getRequestURI();
		String contextPath = request.getContextPath();
		String url = requestUri.substring(contextPath.length());
      
        log.info("requestUri:"+requestUri);  
        log.info("contextPath:"+contextPath);  
        log.info("url:"+url);  
        
        String username =  (String)request.getSession().getAttribute("user"); 
        if(username == null){
        	log.info("Interceptor：跳转到login页面！");
        	request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);
        	return false;
        }else
            return true;   
    }  
  
    /**
     * 在业务处理器处理请求执行完成后,生成视图之前执行的动作   
     * 可在modelAndView中加入数据，比如当前时间
     */
    @Override  
    public void postHandle(HttpServletRequest request,  
            HttpServletResponse response, Object handler,  
            ModelAndView modelAndView) throws Exception {   
        log.info("==============执行顺序: 2、postHandle================");  
        if(modelAndView != null){  //加入当前时间  
            modelAndView.addObject("var", "测试postHandle");  
        }  
    }  
  
    /** 
     * 在DispatcherServlet完全处理完请求后被调用,可用于清理资源等  
     *  
     * 当有拦截器抛出异常时,会从当前拦截器往回执行所有的拦截器的afterCompletion() 
     */  
    @Override  
    public void afterCompletion(HttpServletRequest request,  
            HttpServletResponse response, Object handler, Exception ex)  
            throws Exception {  
        log.info("==============执行顺序: 3、afterCompletion================");  
    }  

}  

拦截器拦截指定的方法

1.自定义注解@AccessRequired  

import java.lang.annotation.ElementType;  
import java.lang.annotation.RetentionPolicy;  
import java.lang.annotation.Target;  
import java.lang.annotation.Retention;  
  
@Target(ElementType.METHOD)  
@Retention(RetentionPolicy.RUNTIME)  
public @interface AccessRequired {  
      
}  

2.编写controller

    /** 
     * 注解拦截器方法 
     * @return 
     */  
    @RequestMapping(value="/urlinter",method=RequestMethod.GET)  
    @AccessRequired  
    public @ResponseBody String urlInterceptorTest() {  
        return "通过拦截器:user"+request.getAttribute("currUser");  
    }  

3.实现拦截器

/** 
 * 拦截url中的access_token 
 * @author Nob 
 *  
 */  
public class UserAccessApiInterceptor extends HandlerInterceptorAdapter {  
  
    public boolean preHandle(HttpServletRequest request,  
            HttpServletResponse response, Object handler) throws Exception {  
  
        HandlerMethod handlerMethod = (HandlerMethod) handler;  
        Method method = handlerMethod.getMethod();  
        AccessRequired annotation = method.getAnnotation(AccessRequired.class);  
        if (annotation != null) {  
           System.out.println("你遇到了：@AccessRequired");  
           String accessToken = request.getParameter("access_token");  
            /** 
             * Do something 
             */  
            response.getWriter().write("没有通过拦截，accessToken的值为：" + accessToken);  
        }  
        // 没有注解通过拦截  
        return true;  
    }  
}  

注解有@AccessRequired的方法,当访问的时候会进行拦截,校验token是否过期.