neaten up a little. pass in the interceptor function

src/main/java/MitmproxyJava.java

@@ -12,12 +12,8 @@ public class MitmproxyJava {
     private MitmproxyServer server;
     public static final int WEBSOCKET_PORT = 8765;
 
-    public MitmproxyJava(Function<InterceptedMessage, Boolean> messageInterceptor) throws URISyntaxException {
-//        InterceptedMessage message = new InterceptedMessage();
-//        message.message = "hi from message";
-//        messageInterceptor.apply(message);
-
-        server = new MitmproxyServer(new InetSocketAddress("localhost", WEBSOCKET_PORT));
+    public MitmproxyJava(Function<InterceptedMessage, InterceptedMessage> messageInterceptor) throws URISyntaxException {
+        server = new MitmproxyServer(new InetSocketAddress("localhost", WEBSOCKET_PORT), messageInterceptor);
         server.run();
         System.out.println("you started me");
     }

src/main/java/MitmproxyServer.java

@@ -7,11 +7,15 @@
 import java.net.InetSocketAddress;
 import java.nio.ByteBuffer;
 import java.nio.charset.StandardCharsets;
+import java.util.function.Function;
 
 public class MitmproxyServer extends WebSocketServer {
 
-    public MitmproxyServer(InetSocketAddress address) {
+    private Function<InterceptedMessage, InterceptedMessage> interceptor;
+
+    public MitmproxyServer(InetSocketAddress address, Function<InterceptedMessage, InterceptedMessage> interceptor) {
         super(address);
+        this.interceptor = interceptor;
     }
 
     @Override
@@ -35,15 +39,26 @@ public void onMessage(WebSocket conn, String message) {
     public void onMessage( WebSocket conn, ByteBuffer message ) {
         System.out.println("received ByteBuffer from "	+ conn.getRemoteSocketAddress());
         InterceptedMessage intercepted = null;
+        InterceptedMessage modifiedMessage = null;
+
         try {
             intercepted = new InterceptedMessage(message);
         } catch (IOException e) {
             System.out.println("Could not parse message");
             e.printStackTrace();
         }
         System.out.println(intercepted.requestURL.toString());
+
+        modifiedMessage = interceptor.apply(intercepted);
+
+        // if the supplied interceptor function does not return a message, assume no changes were intended and just
+        // complete the request
+        if (modifiedMessage == null) {
+            modifiedMessage = intercepted;
+        }
+
         try {
-            conn.send(intercepted.serializedResponseToMitmproxy());
+            conn.send(modifiedMessage.serializedResponseToMitmproxy());
         } catch (JsonProcessingException e) {
             System.out.println("Could not encode response to mitmproxy");
             e.printStackTrace();

src/test/java/MitmproxyJavaTest.java

@@ -13,9 +13,13 @@ public class MitmproxyJavaTest {
     public void ConstructorTest() throws URISyntaxException, IOException, InterruptedException {
         MitmproxyJava proxy = new MitmproxyJava((InterceptedMessage m) -> {
             System.out.println(m.requestURL.toString());
-            return new Boolean(true);
+            return m;
         });
         System.out.println("advanced in test");
         proxy.stop();
     }
+
+    //todo test not modifying (by not returning)
+
+    //todo test modifying a response
 }