Java之拦截器与过滤器

拦截器是SpringMVC的技术

过滤器的Servlet的技术

先过过滤器，过滤器过完成才到DispatcherServlet；

拦截器归属于SpringMVC，只可能拦SpringMVC的东西；

拦截器说白了就是为了增强，可以在请求前进行增强，也可以在请求后进行增强，但是不一定同时在前后都增强。

项目地址

package com.test.filtertest.inter;

import org.springframework.stereotype.Component;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

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


@Component
public class TestInter1 implements HandlerInterceptor {

    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("TestInter1 preHandle...");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("TestInter1 postHandle...");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
        System.out.println("TestInter1 afterCompletion...");
    }
}

package com.test.filtertest.config;

import com.test.filtertest.inter.TestInter1;
import com.test.filtertest.inter.TestInter2;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.servlet.config.annotation.InterceptorRegistry;
import org.springframework.web.servlet.config.annotation.WebMvcConfigurer;


@Configuration
public class WebConfig implements WebMvcConfigurer {

    @Autowired
    private TestInter1 testInter1;

    @Autowired
    private TestInter2 testInter2;

    @Override
    public void addInterceptors(InterceptorRegistry registry) {
        //默认
@WebFilter(filterName = "TestFilter1", urlPatterns = "
@Configuration
public class FilterConfig {

    @Bean
    public FilterRegistrationBean testFilter1() {
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
        Filter testFilter1 = new TestFilter1();
        filterRegistrationBean.setFilter(testFilter1);
        filterRegistrationBean.addUrlPatterns("/*");
        filterRegistrationBean.setName("testFilter1");
        filterRegistrationBean.setOrder(2);//指定过滤顺序，数值越小优先级越高
        return filterRegistrationBean;
    }

    @Bean
    public FilterRegistrationBean testFilter2() {
        FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();
        Filter testFilter2 = new TestFilter2();
        filterRegistrationBean.setFilter(testFilter2);
        filterRegistrationBean.setName("testFilter2");
        filterRegistrationBean.addUrlPatterns("/*");
        filterRegistrationBean.setOrder(1);//指定过滤顺序，数值越小优先级越高
        return filterRegistrationBean;
    }
}

1、同时原本Filter过滤器上的@WebFilter(filterName = “TestFilter1”, urlPatterns = “/*”)
这个注解最好去掉，否则bean重复会报错，要么bean名称不要重复，换个名称。但是不去掉的话@ServletComponentScan也要被保留，最好统一格式，只使用config配置。
2、启动类上的@ServletComponentScan 注解也不需要了，可以去掉了，因为不用扫描@WebFilter注解了。但是如果@WebFilter还保留了，那么就不能去掉了。不然加了@WebFilter的过滤器就不会生效了，因为没扫到。