Spring Boot的过滤器 - 《Spring Boot编程详解》 - 严富坤的知识库专栏(yanfukun.com)

1. Spring Boot过滤器概述
- 1.1 过滤器的定义与作用
- 1.2 过滤器的生命周期
2. 创建Spring Boot过滤器
- 2.1 基础过滤器实现
  - 示例代码
- 2.2 注册过滤器
  - 使用@Bean注解注册过滤器
  - 使用FilterRegistrationBean类注册过滤器
3. 常见过滤器类型
4. 过滤器的高级应用
5. 过滤器的测试
- 5.1 单元测试
  - 示例代码
- 5.2 集成测试
  - 示例代码
6. 过滤器的性能优化
7. 过滤器的安全性
8. 过滤器的监控和日志
- 8.1 记录过滤器的执行时间
  - 示例代码
- 8.2 记录请求和响应的详细信息
  - 示例代码
9. 过滤器的故障处理
- 9.1 捕获和处理异常
  - 示例代码
- 9.2 自定义错误页面
  - 示例代码
10. 过滤器的最佳实践
总结

Spring Boot过滤器是Web应用程序中处理请求和响应的一种重要机制。过滤器能够在请求到达Servlet之前以及响应离开Servlet之后，对其进行预处理或后处理。这些处理可以包括日志记录、安全检查、数据压缩等。本文将详细介绍Spring Boot过滤器，从基础概念到高级应用，涵盖各类过滤器的使用场景、实现方法和最佳实践。

1. Spring Boot过滤器概述

1.1 过滤器的定义与作用

过滤器（Filter）是一种Java EE标准，允许在请求到达Servlet之前和响应离开Servlet之后对其进行处理。它们主要用于以下任务：

请求和响应的日志记录
安全性检查和认证
请求参数的修改和校验
响应的压缩和编码

1.2 过滤器的生命周期

过滤器的生命周期包括初始化（init）、处理（doFilter）和销毁（destroy）三个阶段：

init：在过滤器实例被创建时调用，通常用于资源初始化。
doFilter：在每次请求到达Servlet之前和响应离开Servlet之后调用，是主要的处理逻辑。
destroy：在过滤器实例被销毁时调用，通常用于资源释放。

2. 创建Spring Boot过滤器

2.1 基础过滤器实现

在Spring Boot中创建一个过滤器需要实现javax.servlet.Filter接口，并重写其方法。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
public class MyFilter implements Filter {
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        // 初始化逻辑
    }
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        System.out.println("Request URI is: " + req.getRequestURI());
        chain.doFilter(request, response);  // 调用下一个过滤器或目标资源
    }
    @Override
    public void destroy() {
        // 资源释放逻辑
    }
}

2.2 注册过滤器

在Spring Boot中，可以通过两种方式注册过滤器：使用@Bean注解或通过FilterRegistrationBean类。

使用@Bean注解注册过滤器

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class FilterConfig {
    @Bean
    public FilterRegistrationBean<MyFilter> loggingFilter() {
        FilterRegistrationBean<MyFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new MyFilter());
        registrationBean.addUrlPatterns("/api/*");
        return registrationBean;
    }
}

使用FilterRegistrationBean类注册过滤器

import org.springframework.boot.web.servlet.FilterRegistrationBean;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
public class FilterConfig {
    @Bean
    public FilterRegistrationBean<MyFilter> loggingFilter() {
        FilterRegistrationBean<MyFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new MyFilter());
        registrationBean.addUrlPatterns("/api/*");
        registrationBean.setOrder(1);  // 设置过滤器顺序
        return registrationBean;
    }
}

3. 常见过滤器类型

3.1 日志记录过滤器

日志记录过滤器用于记录请求和响应的详细信息，方便后续的分析和调试。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
public class LoggingFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        long startTime = System.currentTimeMillis();
        chain.doFilter(request, response);
        long endTime = System.currentTimeMillis();
        System.out.println("Request URI: " + req.getRequestURI() + ", Time taken: " + (endTime - startTime) + " ms");
    }
}

3.2 安全过滤器

安全过滤器用于检查请求的合法性，如验证用户身份、权限等。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class SecurityFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        String authHeader = req.getHeader("Authorization");
        if (authHeader == null || !authHeader.startsWith("Bearer ")) {
            res.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
            return;
        }
        // 验证token逻辑
        String token = authHeader.substring(7);
        if (!validateToken(token)) {
            res.setStatus(HttpServletResponse.SC_UNAUTHORIZED);
            return;
        }
        chain.doFilter(request, response);
    }
    private boolean validateToken(String token) {
        // token验证逻辑
        return "valid_token".equals(token);
    }
}

3.3 压缩过滤器

压缩过滤器用于压缩响应数据，提高传输效率。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.zip.GZIPOutputStream;
public class CompressionFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        HttpServletResponse res = (HttpServletResponse) response;
        CompressionResponseWrapper wrappedResponse = new CompressionResponseWrapper(res);
        chain.doFilter(request, wrappedResponse);
        wrappedResponse.finishResponse();
    }
    class CompressionResponseWrapper extends HttpServletResponseWrapper {
        private GZIPOutputStream gzipOutputStream = null;
        private ServletOutputStream servletOutputStream = null;
        private PrintWriter printWriter = null;
        public CompressionResponseWrapper(HttpServletResponse response) throws IOException {
            super(response);
        }
        @Override
        public ServletOutputStream getOutputStream() throws IOException {
            if (servletOutputStream == null) {
                servletOutputStream = createOutputStream();
            }
            return servletOutputStream;
        }
        @Override
        public PrintWriter getWriter() throws IOException {
            if (printWriter == null) {
                printWriter = new PrintWriter(new OutputStreamWriter(getOutputStream(), getCharacterEncoding()));
            }
            return printWriter;
        }
        private ServletOutputStream createOutputStream() throws IOException {
            gzipOutputStream = new GZIPOutputStream(getResponse().getOutputStream());
            return new ServletOutputStream() {
                @Override
                public void write(int b) throws IOException {
                    gzipOutputStream.write(b);
                }
                @Override
                public void close() throws IOException {
                    gzipOutputStream.close();
                }
                @Override
                public void flush() throws IOException {
                    gzipOutputStream.flush();
                }
                @Override
                public boolean isReady() {
                    return false;
                }
                @Override
                public void setWriteListener(WriteListener writeListener) {
                }
            };
        }
        public void finishResponse() throws IOException {
            if (printWriter != null) {
                printWriter.close();
            }
            if (gzipOutputStream != null) {
                gzipOutputStream.close();
            }
        }
    }
}

4. 过滤器的高级应用

4.1 过滤器链

过滤器链（Filter Chain）是多个过滤器依次执行的过程。每个过滤器在调用chain.doFilter()方法时会将请求传递给下一个过滤器。

配置多个过滤器

@Configuration
public class FilterConfig {
    @Bean
    public FilterRegistrationBean<LoggingFilter> loggingFilter() {
        FilterRegistrationBean<LoggingFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new LoggingFilter());
        registrationBean.addUrlPatterns("/api/*");
        registrationBean.setOrder(1);
        return registrationBean;
    }
    @Bean
    public FilterRegistrationBean<SecurityFilter> securityFilter() {
        FilterRegistrationBean<SecurityFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new SecurityFilter());
        registrationBean.addUrlPatterns("/api/*");
        registrationBean.setOrder(2);
        return registrationBean;
    }
}

4.2 异步过滤器

异步过滤器允许在非阻塞模式下处理请求，适用于高并发场景。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.concurrent.CompletableFuture;
public class AsyncFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain
) 
            throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        CompletableFuture.runAsync(() -> {
            try {
                // 异步处理逻辑
                chain.doFilter(request, response);
            } catch (IOException | ServletException e) {
                e.printStackTrace();
            }
        });
    }
}

4.3 自定义过滤器顺序

通过设置过滤器的order属性，可以自定义过滤器的执行顺序。

示例代码

@Configuration
public class FilterConfig {
    @Bean
    public FilterRegistrationBean<LoggingFilter> loggingFilter() {
        FilterRegistrationBean<LoggingFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new LoggingFilter());
        registrationBean.addUrlPatterns("/api/*");
        registrationBean.setOrder(1);  // LoggingFilter先执行
        return registrationBean;
    }
    @Bean
    public FilterRegistrationBean<SecurityFilter> securityFilter() {
        FilterRegistrationBean<SecurityFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new SecurityFilter());
        registrationBean.addUrlPatterns("/api/*");
        registrationBean.setOrder(2);  // SecurityFilter后执行
        return registrationBean;
    }
}

5. 过滤器的测试

5.1 单元测试

通过Mock框架，如Mockito，可以对过滤器进行单元测试。

示例代码

import org.junit.jupiter.api.Test;
import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import javax.servlet.FilterChain;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import static org.mockito.Mockito.*;
public class LoggingFilterTest {
    @Mock
    private HttpServletRequest request;
    @Mock
    private HttpServletResponse response;
    @Mock
    private FilterChain filterChain;
    @Test
    public void testDoFilter() throws IOException, ServletException {
        MockitoAnnotations.initMocks(this);
        LoggingFilter loggingFilter = new LoggingFilter();
        when(request.getRequestURI()).thenReturn("/api/test");
        loggingFilter.doFilter(request, response, filterChain);
        verify(filterChain).doFilter(request, response);
        verify(request).getRequestURI();
    }
}

5.2 集成测试

通过Spring Boot的测试框架，可以对过滤器进行集成测试。

示例代码

import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.boot.test.web.client.TestRestTemplate;
import org.springframework.boot.web.server.LocalServerPort;
import org.springframework.http.ResponseEntity;
import static org.assertj.core.api.Assertions.assertThat;
@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
public class FilterIntegrationTest {
    @LocalServerPort
    private int port;
    @Autowired
    private TestRestTemplate restTemplate;
    @Test
    public void testFilters() {
        String url = "http://localhost:" + port + "/api/test";
        ResponseEntity<String> response = restTemplate.getForEntity(url, String.class);
        assertThat(response.getStatusCode().is2xxSuccessful()).isTrue();
        // 其他断言逻辑
    }
}

6. 过滤器的性能优化

6.1 减少不必要的过滤器处理

确保每个过滤器只处理它关心的请求路径，避免不必要的处理。

示例代码

@Configuration
public class FilterConfig {
    @Bean
    public FilterRegistrationBean<LoggingFilter> loggingFilter() {
        FilterRegistrationBean<LoggingFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new LoggingFilter());
        registrationBean.addUrlPatterns("/api/log/*");  // 仅处理 /api/log/ 路径
        registrationBean.setOrder(1);
        return registrationBean;
    }
}

6.2 异步处理

使用异步过滤器处理耗时操作，减少对请求处理的阻塞。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.concurrent.CompletableFuture;
public class AsyncFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        CompletableFuture.runAsync(() -> {
            try {
                // 异步处理逻辑
                chain.doFilter(request, response);
            } catch (IOException | ServletException e) {
                e.printStackTrace();
            }
        });
    }
}

6.3 缓存结果

对于一些固定响应内容的过滤器，可以使用缓存来提升性能。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;
public class CachingFilter implements Filter {
    private final Map<String, String> cache = new HashMap<>();
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        String requestUri = req.getRequestURI();
        if (cache.containsKey(requestUri)) {
            res.getWriter().write(cache.get(requestUri));
        } else {
            CachingResponseWrapper responseWrapper = new CachingResponseWrapper(res);
            chain.doFilter(request, responseWrapper);
            String content = responseWrapper.getContent();
            cache.put(requestUri, content);
            res.getWriter().write(content);
        }
    }
    class CachingResponseWrapper extends HttpServletResponseWrapper {
        private final StringWriter sw = new StringWriter();
        public CachingResponseWrapper(HttpServletResponse response) {
            super(response);
        }
        @Override
        public PrintWriter getWriter() throws IOException {
            return new PrintWriter(sw);
        }
        public String getContent() {
            return sw.toString();
        }
    }
}

7. 过滤器的安全性

7.1 防止XSS攻击

使用过滤器对请求参数进行校验，防止XSS攻击。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class XSSFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        XSSRequestWrapper wrappedRequest = new XSSRequestWrapper(req);
        chain.doFilter(wrappedRequest, response);
    }
}
class XSSRequestWrapper extends HttpServletRequestWrapper {
    public XSSRequestWrapper(HttpServletRequest request) {
        super(request);
    }
    @Override
    public String getParameter(String name) {
        String value = super.getParameter(name);
        return cleanXSS(value);
    }
    private String cleanXSS(String value) {
        if (value != null) {
            value = value.replaceAll("<", "&lt;").replaceAll(">", "&gt;");
            value = value.replaceAll("\\(", "&#40;").replaceAll("\\)", "&#41;");
            value = value.replaceAll("'", "&#39;");
            value = value.replaceAll("eval\\((.*)\\)", "");
            value = value.replaceAll("[\\\"\\\'][\\s]*javascript:(.*)[\\\"\\\']", "\"\"");
            value = value.replaceAll("script", "");
        }
        return value;
    }
}

7.2 防止CSRF攻击

通过过滤器添加CSRF令牌，防止CSRF攻击。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class CSRFTokenFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        String csrfToken = (String) req.getSession().getAttribute("CSRF_TOKEN");
        if (csrfToken == null) {
            csrfToken = generateCSRFToken();
            req.getSession().setAttribute("CSRF_TOKEN", csrfToken);
        }
        res.addHeader("CSRF-Token", csrfToken);
        chain.doFilter(request, response);
    }
    private String generateCSRFToken() {
        return Long.toHexString(System.currentTimeMillis());
    }
}

7.3 防止SQL注入

通过过滤器对请求参数进行校验，防止SQL注入攻击。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class SQLInjectionFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest
) request;
        HttpServletResponse res = (HttpServletResponse) response;
        SQLInjectionRequestWrapper wrappedRequest = new SQLInjectionRequestWrapper(req);
        chain.doFilter(wrappedRequest, response);
    }
}
class SQLInjectionRequestWrapper extends HttpServletRequestWrapper {
    public SQLInjectionRequestWrapper(HttpServletRequest request) {
        super(request);
    }
    @Override
    public String getParameter(String name) {
        String value = super.getParameter(name);
        return cleanSQLInjection(value);
    }
    private String cleanSQLInjection(String value) {
        if (value != null) {
            value = value.replaceAll("'", "''");
            value = value.replaceAll(";", "");
            value = value.replaceAll("--", "");
        }
        return value;
    }
}

8. 过滤器的监控和日志

8.1 记录过滤器的执行时间

通过日志记录过滤器的执行时间，便于性能监控和调试。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import java.io.IOException;
public class ExecutionTimeLoggingFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        long startTime = System.currentTimeMillis();
        chain.doFilter(request, response);
        long endTime = System.currentTimeMillis();
        System.out.println("Request URI: " + req.getRequestURI() + ", Execution time: " + (endTime - startTime) + " ms");
    }
}

8.2 记录请求和响应的详细信息

通过日志记录请求和响应的详细信息，便于分析和调试。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class RequestResponseLoggingFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        System.out.println("Request URI: " + req.getRequestURI());
        System.out.println("Request Method: " + req.getMethod());
        System.out.println("Request Headers: " + getRequestHeaders(req));
        chain.doFilter(request, response);
        System.out.println("Response Status: " + res.getStatus());
    }
    private String getRequestHeaders(HttpServletRequest request) {
        StringBuilder headers = new StringBuilder();
        request.getHeaderNames().asIterator().forEachRemaining(headerName -> {
            headers.append(headerName).append(": ").append(request.getHeader(headerName)).append("\n");
        });
        return headers.toString();
    }
}

9. 过滤器的故障处理

9.1 捕获和处理异常

通过过滤器捕获和处理请求中的异常，提供统一的错误响应。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class ExceptionHandlingFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        try {
            chain.doFilter(request, response);
        } catch (Exception e) {
            HttpServletResponse res = (HttpServletResponse) response;
            res.setStatus(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            res.getWriter().write("Internal Server Error: " + e.getMessage());
        }
    }
}

9.2 自定义错误页面

通过过滤器实现自定义错误页面，提升用户体验。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class CustomErrorPageFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        try {
            chain.doFilter(request, response);
        } catch (Exception e) {
            HttpServletResponse res = (HttpServletResponse) response;
            res.sendRedirect("/error-page");
        }
    }
}

10. 过滤器的最佳实践

10.1 避免长时间阻塞

避免在过滤器中执行长时间阻塞操作，如IO操作或复杂计算。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class NonBlockingFilter implements Filter {
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse res = (HttpServletResponse) response;
        new Thread(() -> {
            try {
                // 异步处理
                chain.doFilter(request, response);
            } catch (IOException | ServletException e) {
                e.printStackTrace();
            }
        }).start();
    }
}

10.2 合理配置过滤器顺序

根据业务逻辑合理配置过滤器的顺序，确保正确的执行顺序。

示例代码

@Configuration
public class FilterConfig {
    @Bean
    public FilterRegistrationBean<LoggingFilter> loggingFilter() {
        FilterRegistrationBean<LoggingFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new LoggingFilter());
        registrationBean.addUrlPatterns("/api/*");
        registrationBean.setOrder(1);  // LoggingFilter先执行
        return registrationBean;
    }
    @Bean
    public FilterRegistrationBean<SecurityFilter> securityFilter() {
        FilterRegistrationBean<SecurityFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new SecurityFilter());
        registrationBean.addUrlPatterns("/api/*");
        registrationBean.setOrder(2);  // SecurityFilter后执行
        return registrationBean;
    }
}

10.3 使用过滤器链

通过FilterChain有效地组织和管理多个过滤器。

示例代码

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
public class CombinedFilter implements Filter {
    private final Filter[] filters;
    public CombinedFilter(Filter... filters) {
        this.filters = filters;
    }
    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) 
            throws IOException, ServletException {
        new FilterChain() {
            private int index = 0;
            @Override
            public void doFilter(ServletRequest request, ServletResponse response) 
                    throws IOException, ServletException {
                if (index < filters.length) {
                    filters[index++].doFilter(request, response, this);
                } else {
                    chain.doFilter(request, response);
                }
            }
        }.doFilter(request, response);
    }
}

总结

本文详细介绍了Spring Boot过滤器的各个方面，从基础概念到高级应用，涵盖了创建、注册、常见类型、性能优化、安全性、监控、故障处理及最佳实践等内容。通过这些知识，开发者可以更加灵活和高效地处理Web应用程序中的请求和响应，提升应用的性能和安全性。希望这篇文章能帮助您更好地理解和使用Spring Boot过滤器，提高开发效率和代码质量。

在实际开发中，掌握过滤器的使用不仅能够提高代码的可维护性，还能使您的Spring Boot应用更加健壮和灵活。今后，希望大家能多多尝试和应用这些过滤器，并不断总结经验，提升自己的开发技能。