一文详解Java拦截器与过滤器的使用（java过滤器和拦截器的区别和使用场景）

目录流程图拦截器vs过滤器SpringMVC技术架构图项目Demo依赖Interceptor拦截器Filter过滤器1、多Filter不指定过滤顺序2、多Filter指定过滤顺序

流程图

拦截器vs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。

区别

SpringMVC技术架构图

项目Demo

项目地址

依赖

org.springframework.boot

spring-boot-starter-parent

2.2.7.RELEASE

org.springframework.boot

spring-boot-starter-web

Interceptor拦截器

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;

/**

* 拦截器

*

* @author: zhangzengxiu

* @createDate: 2022/4/22

*/

@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...");

}

}

Interceptor拦截器要注册

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;

/**

* @author zhangzengxiu

* @date 2022/4/22

*/

@Configuration

public class WebConfig implements WebMvcConfigurer {

@Autowired

private TestInter1 testInter1;

@Autowired

private TestInter2 testInter2;

@Override

public void addInterceptors(InterceptorRegistry registry) {

//默认/** 拦截所有请求

registry.addInterceptor(testInter1).addPathPatterns("/**");

registry.addInterceptor(testInter2);

}

}

拦截顺序

多拦截器拦截顺序取决于registry的注册顺序

Filter过滤器

1、多Filter不指定过滤顺序

package com.test.filtertest.filter;

import org.springframework.core.annotation.Order;

import javax.servlet.*;

import javax.servlet.annotation.WebFilter;

import java.io.IOException;

/**

* @author zhangzengxiu

* @date 2022/4/22

*/

@WebFilter(filterName = "TestFilter1", urlPatterns = "/*")

//@Order(2) //filter这样定义拦截顺序无效，还是会按照类名去拦截

public class TestFilter1 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("TestFilter1 filter before ...");

filterChain.doFilter(servletRequest, servletResponse);

System.out.println("TestFilter1 filter after ...");

}

@Override

public void destroy() {

}

}

加了@WebFilter注解的过滤器要生效，需要在启动类上加一个注解@ServletComponentScan

2、多Filter指定过滤顺序

如果要设置过滤顺序的话，在Filter上添加@Order 不会生效，还是会默认根据Filter过滤器的类名去进行过滤。

如果想要指定拦截顺序，需要添加一个配置类，通过设置Order的值去设置过滤顺序，Order数值越小优先级越高

package com.test.config;

import com.test.filter.TestFilter1;

import com.test.filter.TestFilter2;

import org.springframework.boot.web.servlet.FilterRegistrationBean;

import org.springframework.context.annotation.Bean;

import org.springframework.context.annotation.Configuration;

import javax.servlet.Filter;

/**

* filter过滤器配置

*

* @author: zhangzengxiu

* @createDate: 2022/4/24

*/

@Configuration

public class FilterConfig {

@Bean

public FilterRegistrationBean testFilter1() {

FilterRegistrationBean filterRegistrationBean = new FilterRegistrationBean();

Filter testFilter1 = new TestFilter1();

dhwEclig 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。

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