Spring Boot 之web Filter --不支持排序的使用

Spring Boot 之web Filter --不支持排序的使用

在severlet3.0以后的环境下，我们使用web Filter，可以利用注解WebFilter使用java配置的方式。

同样，spring boot环境一下依然可以使用：

package com.sdcuike.practice.web;

import java.io.IOException;

import javax.annotation.Resource;
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 org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.core.annotation.Order;

import com.sdcuike.practice.config.CommonConfig;

/**
 * FilterDemo1
 * 
 * @author sdcuike
 *         

 *         Created on 2017-02-10
 *         

 *         支持依赖注入
 */
@WebFilter("/*")
public class FilterDemo1 implements Filter {
    private final Logger log = LoggerFactory.getLogger(getClass());

    @Resource
    private CommonConfig commonConfig;

    @Override
    public void destroy() {
        log.info("" + getClass() + " destroy");

    }

    @Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2) throws IOException, ServletException {
        log.info("" + getClass() + " doFilter " + commonConfig);
        arg2.doFilter(arg0, arg1);

    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {
        log.info("" + getClass() + " init");

    }

}

  为了让spring boot扫描到注解的filter，我们还需要配置：

package com.sdcuike.practice.web;

import org.springframework.boot.web.servlet.ServletComponentScan;
import org.springframework.context.annotation.Configuration;

/**
 * web 组件配置
 * 
 * @author sdcuike
 *         

 *         Created on 2017-02-09
 *         

 *         web组件如Filter等注解配置，支持依赖注入，但spring的@Order注解不支持排序;
 * @WebFilter has no element to define the order of filter of execution.
 */
@Configuration
@ServletComponentScan
public class WebComponentConfig {

}

由于 WebComponentConfig的包和filter所在的包同级目录（子目录也可以），注解ServletComponentScan默认

扫描与配置类WebComponentConfig同包及子包下面的filter，我们可以省去包名的书写。

 大家也看到了注解：@WebFilter has no element to define the order of filter of execution.但

我们使用filter的时候必须排序的情况下，就不能用这个方法了。

  有人说，我们可以利用注解：@Order如：

@WebFilter("/*")
@Order(1)
public class FilterDemo2 implements Filter {
    private final Logger log = LoggerFactory.getLogger(getClass());

  或者实现spring 的排序接口：Ordered ，如：

package com.sdcuike.practice.web;

import java.io.IOException;

import javax.annotation.Resource;
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 org.springframework.core.Ordered;

import com.sdcuike.practice.config.CommonConfig;

import lombok.extern.slf4j.Slf4j;

@WebFilter("/*")
@Slf4j
public class FilterDemo5 implements Filter, Ordered {
    private final int    order = 66;

    @Resource
    private CommonConfig commonConfig;

    @Override
    public void destroy() {
        log.info("" + getClass() + " destroy");

    }

    @Override
    public void doFilter(ServletRequest arg0, ServletResponse arg1, FilterChain arg2) throws IOException, ServletException {
        log.info("" + getClass() + " doFilter " + commonConfig);
        arg2.doFilter(arg0, arg1);

    }

    @Override
    public void init(FilterConfig arg0) throws ServletException {
        log.info("" + getClass() + " init");

    }

    @Override
    public int getOrder() {
        return order;
    }

}

对不起，spring boot不支持。详见： https://github.com/spring-projects/spring-boot/issues/8276.

    由于兴趣，我修改了并扩展了spring boot的某些方法，可以支持，详情见以后序列博文，或直接去看源码。

本博客相关源码：https://github.com/sdcuike/spring-boot-practice/tree/master/src/main/java/com/sdcuike/practice/web

<spring-boot.version>1.5.1.RELEASEspring-boot.version>