基于springboot，设计并实现http的网关，并提供示范代码

好的，下面是一个基于Spring Boot的HTTP网关示例代码，供您参考。

首先，您需要在pom.xml文件中添加以下依赖项，以使用Spring Boot：

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

然后，在application.properties文件中添加以下配置项，以指定要代理的HTTP服务的地址：

http.targetUrl=http://localhost:8080

接下来，您可以编写一个类来处理HTTP请求，并将其注入到Spring容器中：

@Component
public class HttpRequestHandler implements Filter {

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
        // 处理HTTP请求
    }
}

然后，您可以编写一个类来创建HTTP代理服务器，并将请求处理器注册到代理服务器中：

@Component
public class HttpProxyServerWrapper {

    private ProxyServer proxyServer;

    @Autowired
    private HttpRequestHandler httpRequestHandler;

    @Value("${http.targetUrl}")
    private String targetUrl;

    @PostConstruct
    public void start() {
        proxyServer = DefaultHttpProxyServer.bootstrap()
                .withPort(8081)
                .withFiltersSource(new HttpFiltersSourceAdapter() {
                    @Override
                    public HttpFilters filterRequest(HttpRequest originalRequest, ChannelHandlerContext ctx) {
                        return new HttpFiltersAdapter(originalRequest) {
                            @Override
                            public HttpResponse clientToProxyRequest(HttpObject httpObject) {
                                if (httpObject instanceof HttpRequest) {
                                    httpRequestHandler.doFilter(httpObject, null, null);
                                }
                                return null;
                            }
                        };
                    }
                })
                .withServerResolver(new HostResolver() {
                    @Override
                    public InetSocketAddress resolve(String host, int port) throws UnknownHostException {
                        return new InetSocketAddress(targetUrl, port);
                    }
                })
                .start();
    }

    @PreDestroy
    public void stop() {
        proxyServer.stop();
    }

    public String getTargetUrl() {
        return targetUrl;
    }
}

最后，您可以编写一个控制器类来提供HTTP接口，允许用户配置要代理的HTTP服务地址：

@RestController
@RequestMapping("/http")
public class HttpGatewayController {

    @Autowired
    private HttpProxyServerWrapper httpProxyServerWrapper;

    @PostMapping("/start")
    public void start() {
        httpProxyServerWrapper.start();
    }

    @PostMapping("/stop")
    public void stop() {
        httpProxyServerWrapper.stop();
    }

    @PostMapping("/targetUrl")
    public void setTargetUrl(@RequestParam String targetUrl) {
        httpProxyServerWrapper.setTargetUrl(targetUrl);
    }
}

这里只是一个简单的示例代码，您可以根据自己的需求进行修改和扩展。完整的代码可以在Github上找到：https://github.com/youxilua/springboot-http-gateway-example