增加tracker转发

Change-Id: I5aad9b143371870714b49040708170f578f7df89
diff --git a/src/main/java/tracker/DataCaptureServer.java b/src/main/java/tracker/DataCaptureServer.java
new file mode 100644
index 0000000..57ce8d0
--- /dev/null
+++ b/src/main/java/tracker/DataCaptureServer.java
@@ -0,0 +1,33 @@
+package tracker;
+
+import java.io.IOException;
+import java.net.InetSocketAddress;
+
+import org.simpleframework.http.core.ContainerServer;
+import org.simpleframework.transport.connect.Connection;
+import org.simpleframework.transport.connect.SocketConnection;
+
+import entity.config;
+
+/**
+ * 启动 DataCaptureProxy:
+ * 客户端将 announce 请求发到本机 capturePort,
+ * 由 DataCaptureProxy 拦截并转发到 trackerHost:trackerPort。
+ */
+public class DataCaptureServer {
+    
+    public static void start() throws IOException {
+        String trackerHost = config.trackerHost;
+        int    trackerPort = config.trackerPort;
+        int    capturePort = config.capturePort;
+
+        DataCaptureProxy proxy = new DataCaptureProxy(trackerHost, trackerPort);
+        ContainerServer server = new ContainerServer(proxy);
+        Connection      conn   = new SocketConnection(server);
+
+        conn.connect(new InetSocketAddress(capturePort));
+        System.out.println("DataCapture proxy listening on port "
+            + capturePort + ", forwarding to "
+            + trackerHost + ":" + trackerPort);
+    }
+}