springboot怎么设置Request和Response压缩从而节省流量/带宽

可以通过使用Spring Boot中的过滤器(Filter)来实现请求和响应的压缩。具体步骤如下：

1. 在pom.xml中添加以下依赖：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

<dependency>
    <groupId>com.github.ziplet</groupId>
    <artifactId>ziplet-filter-servlet</artifactId>
    <version>2.1.2</version>
</dependency>

2. 在application.properties文件中添加以下配置：

server.compression.enabled=true
server.compression.mime-types=application/json,application/xml,text/html,text/plain
server.compression.min-response-size=1024

其中，`server.compression.enabled`表示是否启用压缩，`server.compression.mime-types`表示需要压缩的内容类型，`server.compression.min-response-size`表示响应内容超过多少字节才压缩。

3. 创建一个过滤器类并实现Filter接口：

public class CompressionFilter implements Filter {

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        HttpServletRequest httpRequest = (HttpServletRequest) request;
        HttpServletResponse httpResponse = (HttpServletResponse) response;

        if (isGzipSupported(httpRequest) && notAlreadyCompressed(httpResponse)) {
            GZIPResponseWrapper gzipResponse = new GZIPResponseWrapper(httpResponse);
            chain.doFilter(request, gzipResponse);
            gzipResponse.finish();
            return;
        }

        chain.doFilter(request, response);
    }

    private boolean isGzipSupported(HttpServletRequest request) {
        String encoding = request.getHeader("Accept-Encoding");
        return (encoding != null && encoding.contains("gzip"));
    }

    private boolean notAlreadyCompressed(HttpServletResponse response) {
        return (response.getHeader("Content-Encoding") == null);
    }

    // GZIPResponseWrapper类是对HttpServletResponse进行封装，实现GZIP压缩
    private static class GZIPResponseWrapper extends HttpServletResponseWrapper {
        private GZIPOutputStream gzipOutputStream;

        public GZIPResponseWrapper(HttpServletResponse response) throws IOException {
            super(response);
            this.gzipOutputStream = new GZIPOutputStream(response.getOutputStream());
        }

        @Override
        public ServletOutputStream getOutputStream() throws IOException {
            return new ServletOutputStream() {
                @Override
                public void write(int b) throws IOException {
                    gzipOutputStream.write(b);
                }

                @Override
                public void flush() throws IOException {
                    gzipOutputStream.flush();
                    super.flush();
                }

                @Override
                public void close() throws IOException {
                    gzipOutputStream.close();
                    super.close();
                }
            };
        }

        @Override
        public PrintWriter getWriter() throws IOException {
            return new PrintWriter(new OutputStreamWriter(gzipOutputStream, getResponse().getCharacterEncoding()));
        }
    }
}

4. 在Spring Boot应用程序的配置类中添加一个FilterRegistrationBean，将上述过滤器类注册为过滤器：

@Configuration
public class WebConfig {

    @Bean
    public FilterRegistrationBean<CompressionFilter> compressionFilter() {
        FilterRegistrationBean<CompressionFilter> registrationBean = new FilterRegistrationBean<>();
        registrationBean.setFilter(new CompressionFilter());
        registrationBean.addUrlPatterns("/*");
        return registrationBean;
    }
}

完成以上步骤后，请求和响应的内容会被自动压缩。