SpringBoot——SpringBoot中使用过滤器Filter的两种方式

Posted 2021-06-14 张起灵-小哥

1.方式一（使用注解）

首先，我们写一个Filter。要求就是简单的打印一句话。

在MyFilter这个类的上方使用 @WebFilter 注解来创建Filter即可。

package com.songzihao.springboot.filter;

import javax.servlet.*;
import javax.servlet.annotation.WebFilter;
import java.io.IOException;

/**
 *
 */
@WebFilter(urlPatterns = "/myfilter")
public class MyFilter implements Filter {
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("======您已进入过滤器======");

        filterChain.doFilter(servletRequest,servletResponse);
    }
}

之后在SpringBoot项目的入口类上方使用注解 @ServletComponentScan 注解来扫描filter包中的注解即可。

package com.songzihao.springboot;

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

@SpringBootApplication
@ServletComponentScan(basePackages = "com.songzihao.springboot.filter")
public class Application {

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

}

最后启动测试。

---

2.方式二（定义配置类）

仍然是先写一个 Filter。这次不使用注解。 

package com.songzihao.springboot.filter;

import javax.servlet.*;
import java.io.IOException;

/**
 *
 */
public class MyFilter implements Filter {
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        System.out.println("======您已进入过滤器======");

        filterChain.doFilter(servletRequest,servletResponse);
    }
}

之后写一个控制层controller。

package com.songzihao.springboot.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

/**
 *
 */
@Controller
public class UserController {

    @RequestMapping(value = "/user/detail")
    public @ResponseBody String userDetail() {
        return "/user/detail";
    }

    @RequestMapping(value = "/center")
    public @ResponseBody String center() {
        return "center";
    }
}

然后再写一个配置类！！！

package com.songzihao.springboot.config;

import com.songzihao.springboot.filter.MyFilter;
import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 *
 */
@Configuration //定义此类为配置类
public class FilterConfig {

    @Bean
    public FilterRegistrationBean myFilterRegistrationBean() {
        //注册过滤器
        FilterRegistrationBean filterRegistrationBean=new FilterRegistrationBean(new MyFilter());
        //添加过滤路径
        filterRegistrationBean.addUrlPatterns("/user/*");
        return filterRegistrationBean;
    }
}

最后启动测试。