springboot filter使用配置

一 ，springboot使用filter有两种方式一种是通过FilterRegistrationBean代码注册，一种是通过注解@WebFilter

1，注解@WebFilter

 需要在主程序Applicaiton上开启@ServletComponentScan

 新建一个 Filter类，MyFilter继承Filter，类上加上@WebFilter注解

package com.kerry.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;


@WebFilter(filterName="myFilter",urlPatterns="/filter/*")
public class MyFilter implements Filter{

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {

		System.out.println("@WebFilter myFilter init ");
	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		System.out.println("@WebFilter myFilter doFilter");
		
        chain.doFilter(request, response);
		
	}

	@Override
	public void destroy() {
		System.out.println("@WebFilter myFilter destroy ");
		
	}

}

然后启动springboot项目的时候，容器会初始化init方法

2 通过 注册FilterRegistrationBean

新建一个MyFilter1类继承Filter

package com.kerry.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;

public class MyFilter1 implements Filter{

	@Override
	public void init(FilterConfig filterConfig) throws ServletException {

		System.out.println(" myFilter1 init ");
	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {
		System.out.println("myFilter1 doFilter");
		
        chain.doFilter(request, response);
		
	}

	@Override
	public void destroy() {
		System.out.println("myFilter1 destroy ");
		
	}

}

再注册myfilter1

package com.kerry.configure;

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

//import com.kerry.filter.MyFilter;
import com.kerry.filter.MyFilter1;

@Configuration
public class FilterConfigure {
	
	@Bean
	public FilterRegistrationBean filterRegistrationBean(){
		FilterRegistrationBean frb = new FilterRegistrationBean();
		frb.setFilter(new MyFilter1());
		frb.addUrlPatterns("/filter1/*");
		return frb;
	}
	
//	@Bean
//	public FilterRegistrationBean filter1RegistrationBean(){
//		FilterRegistrationBean frb = new FilterRegistrationBean();
//		frb.setFilter(new MyFilter());
//		frb.addUrlPatterns("/filter/hello/*");
//		return frb;
//	}

	
//	@Bean
//	......
	
	
}

然后启动项目，会看控制台打印init信息

补充点，当都使用FilterRegistrationBean注册Filter的时候，如果UrlPatterns一个是 /filter1/* 一个 /filter/hello/*  

到底是怎么顺序呢？

package com.kerry.configure;

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import com.kerry.filter.MyFilter;
import com.kerry.filter.MyFilter1;

@Configuration
public class FilterConfigure {
	
	@Bean
	public FilterRegistrationBean filterRegistrationBean(){
		FilterRegistrationBean frb = new FilterRegistrationBean();
		frb.setFilter(new MyFilter1());
		frb.addUrlPatterns("/filter/*");
		return frb;
	}
	
	@Bean
	public FilterRegistrationBean filter1RegistrationBean(){
		FilterRegistrationBean frb = new FilterRegistrationBean();
		frb.setFilter(new MyFilter());
		frb.addUrlPatterns("/filter/hello/*");
		return frb;
	}

	
//	@Bean
//	......
	
	
}

init顺序  myFilter1 init ，myFilter init 

测试结果发现   当访问 /filter/hello/123 的时候， 会先执行 myFilter1 doFilter（/filter/*） 再执行myFilter doFilter(/filter/hello/*)

因为两个filter都匹配了url所以 都会执行。

接着替换两个方法的顺序，调换下 再看

init顺序没有变化， myFilter1 init ，myFilter init

测试结果发现   当访问 /filter/hello/123 的时候， 会先执行myFilter doFilter(/filter/hello/*)再执行 myFilter1 doFilter（/filter/*） 

执行顺序和上面完全相反

接着测试 把Myfilter的urlPatterns改为/filter/hello 会发现

	@Bean
	public FilterRegistrationBean filterRegistrationBean(){
		FilterRegistrationBean frb = new FilterRegistrationBean();
		frb.setFilter(new MyFilter1());
		frb.addUrlPatterns("/filter/*");
		return frb;
	}
	
	@Bean
	public FilterRegistrationBean filter1RegistrationBean(){
		FilterRegistrationBean frb = new FilterRegistrationBean();
		frb.setFilter(new MyFilter());
		frb.addUrlPatterns("/filter/hello");
		return frb;
	}

输入url  /filter/hello/123 结果  myFilter1 doFilter(/filter/*） 只执行了一个filter  因为url只符合第一个myfilter1

输入url  /filter/hello  结果 先执行 myFilter1 doFilter（/filter/*），后执行 myFilter doFilter(/filter/hello) 两个filter都会执行

接着把两个bean注册的方法顺序改变下，

	@Bean
	public FilterRegistrationBean filter1RegistrationBean(){
		FilterRegistrationBean frb = new FilterRegistrationBean();
		frb.setFilter(new MyFilter());
		frb.addUrlPatterns("/filter/hello");
		return frb;
	}
	
	@Bean
	public FilterRegistrationBean filterRegistrationBean(){
		FilterRegistrationBean frb = new FilterRegistrationBean();
		frb.setFilter(new MyFilter1());
		frb.addUrlPatterns("/filter/*");
		return frb;
	}

init 顺序  myFilter1 init ，myFilter init  顺序没有变过

输入url  /filter/hello/123 结果  myFilter1 doFilter(/filter/*） 只执行了一个filter 因为只符合myfilter1的情况

输入url  /filter/hello  结果  先执行myFilter doFilter(/filter/hello) ，后执行myFilter1 doFilter（/filter/*）两个filter都会执行 但是顺序也改变了

综上测试结论： 多个filter且 url具有重复过滤的时候，注册filterbean的init顺序 是通过filterNmae进行字符串字典排序注册的，fileter默认名字是类名第一个字母小写

执行顺序都符合url filter的情况下是先注册先执行

附上项目代码结构：