SpringBoot集成之过滤器

太过爱你忘了你带给我的痛 2021-10-18 12:22 268阅读 0赞

在开发过程中，我们通常需要过滤一些请求，如访问某个接口判断登陆是否验证等。springboot下过滤器有两种实现方式

###     1.注解方式 ###

使用该过滤器的时候需添加@WebFilter注解，另外还需要@Component注解，将该类作为组件，注入spring容器中。

package com.example.demo.filter;
    
    
    import java.io.IOException;
    import javax.servlet.Filter;
    import javax.servlet.FilterChain;
    import javax.servlet.FilterConfig;
    import javax.servlet.ServletException;
    import javax.servlet.ServletRequest;
    import javax.servlet.ServletResponse;
    import javax.servlet.annotation.WebFilter;
    import javax.servlet.http.HttpServletRequest;
    import lombok.extern.slf4j.Slf4j;
    import org.springframework.stereotype.Component;
    
    
    /**
     * Created by linjiaming
     */
    @Slf4j
    @Component
    @WebFilter(value = "/hello")
    public class HelloFilter2 implements Filter {
    
    
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
    
        }
    
        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
                FilterChain filterChain) throws IOException, ServletException {
            log.info("进入到过滤器2啦");
            filterChain.doFilter(servletRequest,servletResponse);
        }
    
        @Override
        public void destroy() {
    
        }
    }

值得一提的是，该过滤器的日志打印方式是lombok插件自带的注解@Slf4j。该插件的功能很强大，可自动为实体类生成get，set方法等。使用时需先下载对应插件，以及在pom文件里引入对应的依赖

###      2.bean注入方式 ###

首先自定义filter，然后在springboot启动类下配置一个过滤的bean，若不在springboot的启动类下配置，在其他的类上使用时，需在类上写上@Configuration，标志这个类是一个配置类。springboot启动类注解@springbootApplication内部含有该注解,所以无需配置。

package com.example.demo.filter;
    
    
    import java.io.IOException;
    import javax.servlet.Filter;
    import javax.servlet.FilterChain;
    import javax.servlet.FilterConfig;
    import javax.servlet.ServletException;
    import javax.servlet.ServletRequest;
    import javax.servlet.ServletResponse;
    import lombok.extern.slf4j.Slf4j;
    
    
    /**
     * Created by linjiaming
     */
    @Slf4j
    public class HelloFilter1 implements Filter {
    
        @Override
        public void init(FilterConfig filterConfig) throws ServletException {
    
        }
    
        @Override
        public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse,
                FilterChain filterChain) throws IOException, ServletException {
            log.info("进入到过滤器1啦");
            //放行至下一个过滤器
            filterChain.doFilter(servletRequest,servletResponse);
        }
    
        @Override
        public void destroy() {
    
        }
    }

package com.example.demo;
    
    import com.example.demo.filter.HelloFilter1;
    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 registrationBean(){
            FilterRegistrationBean filter = new FilterRegistrationBean(new HelloFilter1());
            filter.addUrlPatterns("/hello");
            //多个过滤器时执行顺序
            //filter.setOrder(1);
            return filter;
        }
    }