springboot实现反向代理，动态代理目标地址

网上找了很多文章，各种照搬，只能自己实现

基于开源项目HTTP-Proxy-Servlet实现

开源项目地址：https://github.com/mitre/HTTP-Proxy-Servlet

1. 添加依赖

<dependency>
    <groupId>org.mitre.dsmiley.httpproxy</groupId>
    <artifactId>smiley-http-proxy-servlet</artifactId>
    <version>1.11</version>
</dependency>

2. 实现自己的ProxyServlet，重写service方法，官方通过配置servlet参数只能代理一个目标地址，通过自己拓展service方法，进行逻辑判断可以动态代理到不同的目标地址，参考代码如下：

    @Override
    protected void service(HttpServletRequest servletRequest, HttpServletResponse servletResponse) throws ServletException, IOException {

        String targetUri = "http://www.baidu.com/";

        servletRequest.setAttribute(ATTR_TARGET_URI, null);
        super.targetUri = targetUri;

        URI uri = null;
        try {
            uri = new URI(targetUri);
        } catch (URISyntaxException e) {
            log.error("创建URI对象出错, targetUri[{}]", targetUri, e);
        }
        servletRequest.setAttribute(ATTR_TARGET_HOST, null);
        super.targetHost = URIUtils.extractHost(uri);

        super.service(servletRequest, servletResponse);

    }

3. springboot中注册servlet，参考代码如下：

@Configuration
public class ProxyServletConfiguration {

    @Bean
    public ServletRegistrationBean<DiskProxyServlet> servletServletRegistrationBean() {
        ServletRegistrationBean<DiskProxyServlet> servletRegistrationBean = new ServletRegistrationBean<>(new DiskProxyServlet(), "/toProxy");
        servletRegistrationBean.addInitParameter(ProxyServlet.P_LOG, "true");
        return servletRegistrationBean;
    }

}

4. 浏览器访问http://ip:port/toProxy，会代理到百度首页；