Springboot过滤器和拦截器详解及使用场景
拦截器（Interceptor）：可以拿到你请求的控制器和方法，却拿不到请求方法的参数。
切片（Aspect）: 可以拿到方法的参数，但是却拿不到http请求和响应的对象
二、过滤器
=====
两种方式：
1、使用spring boot提供的FilterRegistrationBean注册Filter
2、使用原生servlet注解定义Filter
两种方式的本质都是一样的，都是去FilterRegistrationBean注册自定义Filter
方式一: （使用spring boot提供的FilterRegistrationBean注册Filter ）
①、先定义Filter：
package com.corwien.filter;
import javax.servlet.*;
import java.io.IOException;
public class MyFilter implements Filter {
@Override public void init(FilterConfig filterConfig) throws ServletException {
}
@Override public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { // do something 处理request 或response
// doFilter()方法中的servletRequest参数的类型是ServletRequest，需要转换为HttpServletRequest类型方便调用某些方法
System.out.println(“filter1”); // 调用filter链中的下一个filter
HttpServletRequest request = (HttpServletRequest) servletRequest;
HttpServletResponse response = (HttpServletResponse) servletResponse;
String ip = request.getRemoteAddr();
String url = request.getRequestURL().toString();
SimpleDateFormat sdf = new SimpleDateFormat(“yyyy-MM-dd HH:mm:ss”);
Date d = new Date();
String date = sdf.format(d);
System.out.printf(“%s %s 访问了 %s%n”, date, ip, url);
filterChain.doFilter(request, response);
}
@Override public void destroy() {
}
}
②、注册自定义Filter
@Configuration
public class FilterConfig {
@Bean
public FilterRegistrationBean registrationBean() {
** FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean(new** MyFilter());
filterRegistrationBean.addUrlPatterns(“/*”);
return filterRegistrationBean;
}
}
方式一的①②步骤可以用下面这段代码代替：
@Configuration public class FilterConfig {
@Bean public FilterRegistrationBean registFilter() {
FilterRegistrationBean registration **= new FilterRegistrationBean();
registration.setFilter(new** LogCostFilter());
registration.addUrlPatterns(“/*”);
registration.setName(“LogCostFilter”);
registration.setOrder(1); return registration;
}
}
public class LogCostFilter implements Filter {
@Override public void init(FilterConfig filterConfig) throws ServletException {
}
@Override public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { long start = System.currentTimeMillis();
filterChain.doFilter(servletRequest,servletResponse);
System.out.println(“Execute cost=”+(System.currentTimeMillis()-start));
}
@Override public void destroy() {
}
方式二：（使用原生servlet注解定义Filter ）
// 注入spring容器
@Component // 定义filterName 和过滤的url
@WebFilter(filterName = “my2Filter” ,urlPatterns = “/*”) public class My2Filter implements Filter {
@Override public void init(FilterConfig filterConfig) throws ServletException {
}
@Override public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
System.out.println(“filter2”);
}
@Override public void destroy() {
}
}
这里直接用**@WebFilter就可以进行配置，同样，可以设置url匹配模式，过滤器名称等。这里需要注意一点的是@WebFilter这个注解是Servlet3.0的规范，并不是Spring boot提供的。除了这个注解以外，我们还需在启动类中加另外一个注解：@ServletComponetScan，指定扫描的包。**
三、拦截器的配置
========
实现拦截器可以通过继承 HandlerInterceptorAdapter类也可以通过实现HandlerInterceptor这个接口。另外，如果preHandle方法return true，则继续后续处理。
首先我们实现拦截器类：
public class LogCostInterceptor implements HandlerInterceptor { long start = System.currentTimeMillis();
@Override public boolean preHandle(HttpServletReque 《一线大厂Java面试题解析+后端开发学习笔记+最新架构讲解视频+实战项目源码讲义》无偿开源 威信搜索公众号【编程进阶路】 st httpServletRequest, HttpServletResponse httpServletResponse, Object o) throws Exception {
start = System.currentTimeMillis(); return true;
}
@Override public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
System.out.println(“Interceptor cost=”+(System.currentTimeMillis()-start));
}
@Override public void afterCompletion(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, Exception e) throws Exception {