spring boot 过滤器、拦截器的区别与使用

拦截器与过滤器的区别：

3、过滤器的实现基于回调函数。而拦截器（代理模式）的实现基于反射，代理分静态代理和动态代理，动态代理是拦截器的简单实现。

何时使用拦截器？何时使用过滤器？

• 如果是非spring项目，那么拦截器不能用，只能使用过滤器。
• 如果是处理controller前后，既可以使用拦截器也可以使用过滤器。
• 如果是处理dispaterServlet前后，只能使用过滤器。

spring boot 使用过滤器

package com.hwm.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 System.out.println("filter1"); // 调用filter链中的下一个filter filterChain.doFilter(servletRequest,servletResponse); } @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; } }

方式二：

// 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() { } }

Spring boot拦截器的使用：

①、定义拦截器：

public class MyInterceptor implements HandlerInterceptor { 
     @Override public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception { System.out.println("preHandle"); return true; } @Override public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable ModelAndView modelAndView) throws Exception { System.out.println("postHandle"); } @Override public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, @Nullable Exception ex) throws Exception { System.out.println("afterCompletion"); } } 

②、配置拦截器：

@Configuration public class InterceptorConfig implements WebMvcConfigurer { 
     @Override public void addInterceptors(InterceptorRegistry registry) { registry.addInterceptor(new MyInterceptor()); } }

③Controller演示：

@RestController public class UController { @GetMapping("/home") public String home(){ System.out.println("home"); return "myhome"; } 标题  }