SpringBoot中的filter

在 Spring Boot 中使用 Filter 与前面的使用 Servlet 相似，根据 Filter 注册方式的不同，有两种使用方式。若使用的是 Servlet3.0+版本，则两种方式均可使用；若使用的是 Servlet2.5版本，则只能使用配置类方式。

1.注解方式

若使用的是 Servlet3.0+版本，可以直接使用 Filter 的注解对 Filter 进行注册。其总步骤有
两步：

• 在定义好的 Filter 上使用@WebFilter 注解
• 在入口类上添加@ServletComponentScan 注解 —>需要写扫描的包

1.1创建springboot

1.2创建filter

自定义filter实现Filter接口

package com.example.demo.filter;

import lombok.extern.slf4j.Slf4j;
import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @author Created by niugang on 2019/7/20/15:46
 */
@WebFilter("/*")
@Slf4j
public class AccesLogFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        log.info("AccesLogFilter init");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        String requesturi = request.getRequestURI();

        log.info("Request URI:{}",requesturi);
        filterChain.doFilter(request,response);
    }

    @Override
    public void destroy() {
        log.info("AccesLogFilter destroy");
    }
}

1.3修改springboot启动入口

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.ServletComponentScan;

@SpringBootApplication
@ServletComponentScan(basePackages="com.example.demo.filter")
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

}

2.配置方式

若使用的是 Servlet2.5 版本，没有 Filter 注解，此时只能使用配置类方式。其总步骤有
两步，与@ServletComponentScan 注解无关。

• 定义 Filter
• 定义配置类

2.1创建工程

2.2创建filter

package com.example.demo.filter;

import lombok.extern.slf4j.Slf4j;
import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;

/**
 * @author Created by niugang on 2019/7/20/15:46
 */
@Slf4j
public class AccesLogFilter implements Filter {

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        log.info("AccesLogFilter init");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        String requesturi = request.getRequestURI();

        log.info("Request URI:{}",requesturi);
        filterChain.doFilter(request,response);
    }

    @Override
    public void destroy() {
        log.info("AccesLogFilter destroy");
    }
}

2.3修改配置类

package com.example.demo;

import com.example.demo.filter.AccesLogFilter;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
public class DemoApplication {

    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args);
    }

    @Bean
    public FilterRegistrationBean<AccesLogFilter> registration() {
        //创建filter
        AccesLogFilter accesLogFilter = new AccesLogFilter();
        //注册过滤器
        FilterRegistrationBean<AccesLogFilter> registration = new FilterRegistrationBean<>(accesLogFilter);
        //添加条件
        registration.addUrlPatterns("/*");
        return registration;
    }

}

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