解决springboot中配置过滤器以及可能出现的问题

在springboot添加过滤器有两种方式：

1、通过创建FilterRegistrationBean的方式（建议使用此种方式，统一管理，且通过注解的方式若不是本地调试，如果在filter中需要增加cookie可能会存在写不进前端情况）

2、通过注解@WebFilter的方式

通过创建FilterRegistrationBean的方式创建多个filter以及设置执行顺序：

1、创建两个实现Filter接口的类TestFilter1 、TestFilter2

package com.aoxun.core.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 TestFilter1 implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException {} @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { chain.doFilter(request, response); } @Override public void destroy() {}}

package com.aoxun.core.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 TestFilter2 implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException {} @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { chain.doFilter(request, response); } @Override public void destroy() {}}

2、创建配置类

有多个filter就创建多个FilterRegistrationBean ，若需注明filter的执行顺序，可通过registration.setOrder(FilterRegistrationBean.LOWEST_PRECEDENCE - 1)配置，值越大，执行顺序越靠后

package com.aoxun.config.web;import org.springframework.boot.web.servlet.FilterRegistrationBean;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import com.aoxun.core.filter.TestFilter1;import com.aoxun.core.filter.TestFilter2;/** * filter配置 * @author zcj * */@Configurationpublic class FilterConfig2 { @Bean public FilterRegistrationBean companyUrlFilterRegister() { FilterRegistrationBean registration = new FilterRegistrationBean(); //注入过滤器 registration.setFilter(new TestFilter1()); //拦截规则 registration.addUrlPatterns('/*'); //过滤器名称 registration.setName('testFilter1'); //过滤器顺序 registration.setOrder(FilterRegistrationBean.LOWEST_PRECEDENCE); return registration; } @Bean public FilterRegistrationBean outLinkSecurityFilterRegister() { FilterRegistrationBean registration = new FilterRegistrationBean(); //注入过滤器 registration.setFilter(new TestFilter2()); //拦截规则 registration.addUrlPatterns('/*'); //过滤器名称 registration.setName('testFilter2'); //过滤器顺序 registration.setOrder(FilterRegistrationBean.LOWEST_PRECEDENCE - 1); return registration; } }

通过注解@WebFilter的方式

1、在启动类上增加@ServletComponentScan注解，自动扫描带有过滤器注解的包

2、在类上使用@WebFilter

package com.aoxun.core.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 org.springframework.boot.web.servlet.FilterRegistrationBean;import org.springframework.core.annotation.Order;@WebFilter(filterName='testFilter1',urlPatterns= {'/*'})public class TestFilter1 implements Filter { @Override public void init(FilterConfig filterConfig) throws ServletException { // TODO Auto-generated method stub } @Override public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException { chain.doFilter(request, response); } @Override public void destroy() { // TODO Auto-generated method stub }}

注：经测试，@Order并不能实现过滤器排序功能，在springboot中注解的方式增加过滤器可通过修改过滤器文件名称的方式排序，如上的过滤器TestFilter1在TestFilter2前。

补充知识：SpringBoot2.1.x，集成Filter过滤器的三种方式，包含OncePerRequestFilter方式

一）Filter过滤器简介

主要作用：Filter使用户可以改变一个request和修改一个response，它能够在一个request到达servlet之前预处理request，也可以在response离开servlet时处理response。例如收集数据和包装数据，并进行处理。

1、Filter是依赖Servlet容器的，如Tomcat。

2、Filter对所有的请求起作用，并是在sevlet之前处理。可以理解成过滤器中包含拦截器，当一个请求过来，先进行过滤器处理，再看程序是否受理该请求。过滤器执行完后，程序中的拦截器再进行处理。

3、Filter只能处理HttpServletRequest和HttpServletResponse，底层是基于回调函数。

二）SpringBoot集成Filter过滤器

第一步：先创建一个maven项目，引入springboot的jar

<project xmlns='http://maven.apache.org/POM/4.0.0' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:schemaLocation='http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd'> <modelVersion>4.0.0</modelVersion> <groupId>com.oysept</groupId> <artifactId>springboot_filter</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.4.RELEASE</version> <relativePath/> </parent> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> <configuration> <mainClass>com.oysept.FilterApplication</mainClass> </configuration> </plugin> <plugin> <groupId>org.apache.tomcat.maven</groupId> <artifactId>tomcat7-maven-plugin</artifactId> </plugin> </plugins> </build></project>

添加一个application.yml配置文件，指定一个端口

server:

port: 8080

创建一个Demo测试接口

package com.oysept.controller; import org.springframework.web.bind.annotation.RequestMapping;import org.springframework.web.bind.annotation.RequestMethod;import org.springframework.web.bind.annotation.RequestParam;import org.springframework.web.bind.annotation.RestController; /** * Demo Controller * @author ouyangjun */@RestControllerpublic class DemoController { // 带参GET请求: http://localhost:8080/demo/get/param?param=111222333444 @RequestMapping(value = '/demo/get/param', method = RequestMethod.GET) public String getParam(@RequestParam(value = 'param') String param) { System.out.println('=====>进入DemoController /demo/get/param'); return '/demo/get/param,' + param; }}

第二步：使用@WebFilter注解方式，实现Filter过滤器

当使用@WebFilter、@WebServlet、@WebListener等注解时, 需要在springboot启动类中启用@ServletComponentScan注解指定扫描包。

package com.oysept.filter; import java.io.IOException;import java.util.Enumeration; import javax.servlet.FilterChain;import javax.servlet.FilterConfig;import javax.servlet.ServletContext;import javax.servlet.ServletException;import javax.servlet.annotation.WebFilter;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse; import org.springframework.core.env.Environment;import org.springframework.web.filter.OncePerRequestFilter; /** * 过滤器, 过滤所有地址 * 方式一: 使用@WebFilter、@WebServlet、@WebListener等注解时, 需要在springboot启动类中启用@ServletComponentScan注解指定扫描包 * 方式二: 结合@WebFilter和@Component注解一起使用, 但可能会同时注入两个bean, 可能会报错, 可在application.yml配置中启用同名Bean覆盖: spring.main.allow-bean-definition-overriding=true * @author ouyangjun */@WebFilter(value = '/*', filterName = 'oauthFilter')public class OAuthFilter extends OncePerRequestFilter { @Override protected void doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) throws ServletException, IOException { System.out.println('====>进入OAuthFilter doFilterInternal过滤器===='); System.out.println('请求地址: ' + request.getRequestURL()); System.out.println('GET请求参数: '); Enumeration<String> parameters = request.getParameterNames(); String parameterName = ''; while (parameters.hasMoreElements()) { parameterName = parameters.nextElement(); System.out.println('参数名称: ' + parameterName + ', 值: ' + request.getParameter(parameterName)); } // 工具类 //FilterConfig filterConfig = super.getFilterConfig(); //ServletContext servletContext = super.getServletContext(); //Environment environment = super.getEnvironment(); System.out.println('====>结束OAuthFilter doFilterInternal过滤器===='); filterChain.doFilter(request, response); }}

第三步：使用@Component注解方式，实现Filter过滤器

package com.oysept.filter; import java.io.IOException; import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse; import org.springframework.stereotype.Component; /** * 过滤器通过@Component注解注册 * @author ouyangjun */@Componentpublic class PathFilter implements Filter { @Override public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { // 转换 HttpServletRequest request = (HttpServletRequest) servletRequest; HttpServletResponse response = (HttpServletResponse) servletResponse; System.out.println('====>进入PathFilter doFilter过滤器===='); System.out.println('====>结束PathFilter doFilter过滤器===='); filterChain.doFilter(request, response); }}

第四步：通过@Bean注解方式，实现Filter过滤器

@Configuration注解：相当于spring中的<beans>标签

@Bean注解：相当于spring中<bean>标签

package com.oysept.config; import java.io.IOException; import javax.servlet.Filter;import javax.servlet.FilterChain;import javax.servlet.ServletException;import javax.servlet.ServletRequest;import javax.servlet.ServletResponse;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse; import org.springframework.boot.web.servlet.FilterRegistrationBean;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration; /** * @Configuration注解: 相当于spring中的<beans>标签 * @Bean注解: 相当于spring中<bean>标签 * @author ouyangjun */@Configurationpublic class MyFilterConfig { @Bean public FilterRegistrationBean<MyFilter> testFilterRegistration() { FilterRegistrationBean<MyFilter> registration = new FilterRegistrationBean<>(); registration.setFilter(new MyFilter()); registration.addUrlPatterns('/*'); // 配置过滤路径 registration.addInitParameter('paramName', 'paramValue'); // 添加初始值 registration.setName('myFilter'); // 设置filter名称 registration.setOrder(1); // 请求中过滤器执行的先后顺序，值越小越先执行 return registration; } // 实现一个过滤器 public class MyFilter implements Filter { @Override public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException { // 转换 HttpServletRequest request = (HttpServletRequest) servletRequest; HttpServletResponse response = (HttpServletResponse) servletResponse; System.out.println('====>进入MyFilter doFilter过滤器===='); System.out.println('====>结束MyFilter doFilter过滤器===='); filterChain.doFilter(request, response); } }}

第五步：创建一个SpringBoot启动类，并通过@ServletComponentScan注解指定扫描的Filter实现类

package com.oysept; import org.springframework.boot.autoconfigure.SpringBootApplication;import org.springframework.boot.builder.SpringApplicationBuilder;import org.springframework.boot.web.servlet.ServletComponentScan; /** * @ServletComponentScan注解不指定扫描包时, 默认扫描当前包和子包 * @author ouyangjun */@SpringBootApplication@ServletComponentScan(basePackages = 'com.oysept.filter')public class FilterApplication { public static void main(String[] args) { new SpringApplicationBuilder(FilterApplication.class).run(args); }}

启动main方法，在浏览器输入地址：http://localhost:8080/demo/get/param?param=111222333444

在控制台查看打印日志：

项目结构图：

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