Java之Interceptor和Filter

 

最近研究了下Spring的HandlerInterceptor和Java的Filter，因为经常搞混它们两个，今天整理个笔记记录一下。

 

HandlerInterceptor 是Spring里面的拦截器

Filter是Java里面的过滤器

 

共同点 还是贴下Java里面的注释吧，解释还是很到位的：

 * <p>A HandlerInterceptor gets called before the appropriate HandlerAdapter

 * triggers the execution of the handler itself. This mechanism can be used

 * for a large field of preprocessing aspects, e.g. for authorization checks,

 * or common handler behavior like locale or theme changes. Its main purpose

 

 * is to allow for factoring out repetitive handler code.

 

 * <p>HandlerInterceptor is basically similar to a Servlet 2.3 Filter, but in

 * contrast to the latter it just allows custom pre-processing with the option

 * of prohibiting the execution of the handler itself, and custom post-processing.

 * Filters are more powerful, for example they allow for exchanging the request

 * and response objects that are handed down the chain. Note that a filter

 * gets configured in web.xml, a HandlerInterceptor in the application context.

 *

 * <p>As a basic guideline, fine-grained handler-related preprocessing tasks are

 * candidates for HandlerInterceptor implementations, especially factored-out

 * common handler code and authorization checks. On the other hand, a Filter

 * is well-suited for request content and view content handling, like multipart

 * forms and GZIP compression. This typically shows when one needs to map the

 * filter to certain content types (e.g. images), or to all requests.

 

  解释下吧：

  HandlerInteceptor一般用于权限验证，以及一些处理风格本地化等公共代码。

  Filter一般用于修改请求内容和界面的解析处理相关。

 

  Inteceptor的三个方法：

  

//做实际的请求之前调用
//返回true会接着链式调用
//返回false终止链式调用
boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler)
	    throws Exception;


//请求之后，解析视图界面之前调用
void postHandle(
			HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView)
			throws Exception;

//解析完界面之后调用
void afterCompletion(
			HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
			throws Exception;

// 在mvc-dispatcher-servlet.xml或者applicationContext.xml中配置
    <!--interceptors begin-->
    <mvc:interceptors>
        <bean class="com.xxx.AllInterceptor"/>
    </mvc:interceptors>
    <!--interceptors end-->

   

    Filter配置

    

@Component
public class RequestLogFilter implements Filter{

	@Override
	public void destroy() {
		System.out.println("destory");
	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		// TODO Auto-generated method stub
		System.out.println("doFilter");
		chain.doFilter(request , response);
		
	}

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {
		// TODO Auto-generated method stub
		System.out.println("init");
		
	}

}


// web.xml配置
<filter>
    <filter-name>testFilter</filter-name>
    <filter-class>com.abcd.system.RequestLogFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>testFilter</filter-name>
    <url-pattern>/*</url-pattern>
</filter-mapping>

   

   测试结果顺序：发现filter会在前面处理

   init

   doFilter

   preHandle

   postHandle

   afterCompletion

评论

3 楼 chenaini119 2016-10-25  

>>> inter interceptor
>>> postHandle
>>> afterCompletion
>>> filter doFilter.....
>>> ----------login page ------
我的顺序是反的

2 楼 labreeze 2015-05-23  

shmily2038 写道

简单易懂

呵呵 大家喜欢就好。

1 楼 shmily2038 2015-05-23  

简单易懂