一个可以作为代理服务器或者转发的java类

项目中用到，这里把它给简化和通用了，突出基本思路，具体可以基于这个类来修改。

基于java容器和servlet。

    package com.xxx.first;                import java.io.BufferedReader;        import java.io.IOException;        import java.io.InputStream;        import java.io.InputStreamReader;        import java.io.OutputStream;        import java.io.PrintWriter;        import java.net.HttpURLConnection;        import java.net.URL;        import javax.servlet.http.HttpServletRequest;        import javax.servlet.http.HttpServletResponse;        import org.apache.commons.compress.utils.IOUtils;                public class SimpleProxy {                    /**            * 使用GET提交到目标服务器。            *             * @param request            * @param response            * @param targetUrl            * @throws IOException            */            private void get(HttpServletRequest request, HttpServletResponse response,                String targetUrl) throws IOException {                    URL url = new URL(targetUrl);                                BufferedReader in = new BufferedReader(new InputStreamReader(                url.openStream()));                    String line;            PrintWriter out = response.getWriter();            while ((line = in.readLine()) != null) {                out.println(line);            }            out.flush();            in.close();            }                    /**            * 使用POST提交到目标服务器。            *             * @param request            * @param response            * @param targetUrl            * @throws IOException            */            private void post(HttpServletRequest request, HttpServletResponse response,                String targetUrl) throws IOException {            URL url = new URL(targetUrl);            HttpURLConnection conn = (HttpURLConnection) url.openConnection();                    // 发送POST请求必须设置如下两行            conn.setDoOutput(true);            conn.setDoInput(true);            conn.setRequestMethod("POST");            // 可以拷贝客户端的head信息作为请求的head参数            // conn.setRequestProperty("Charsert", "UTF-8");            conn.setRequestProperty("Content-Type", "application/json");                    // 直接把客户端的BODY传给目标服务器            OutputStream send = conn.getOutputStream();            InputStream body = request.getInputStream();            IOUtils.copy(body, send);            send.flush();            send.close();            body.close();                    // 获取返回值            BufferedReader in = new BufferedReader(new InputStreamReader(                conn.getInputStream()));            PrintWriter out = response.getWriter();            String line;            while ((line = in.readLine()) != null) {                out.println(line);            }            out.flush();            }                }