Further optimize encoding

Author: franz1981

frameworks/Java/netty/src/main/java/hello/HelloServerInitializer.java

@@ -2,15 +2,11 @@
 
 import java.util.concurrent.ScheduledExecutorService;
 
+import io.netty.buffer.ByteBuf;
+import io.netty.buffer.Unpooled;
 import io.netty.channel.ChannelInitializer;
 import io.netty.channel.socket.SocketChannel;
-import io.netty.handler.codec.http.DefaultFullHttpResponse;
-import io.netty.handler.codec.http.DefaultHttpRequest;
-import io.netty.handler.codec.http.HttpMessage;
-import io.netty.handler.codec.http.HttpMethod;
-import io.netty.handler.codec.http.HttpRequestDecoder;
-import io.netty.handler.codec.http.HttpResponseEncoder;
-import io.netty.handler.codec.http.HttpVersion;
+import io.netty.handler.codec.http.*;
 
 public class HelloServerInitializer extends ChannelInitializer<SocketChannel> {
 
@@ -21,6 +17,28 @@ public HelloServerInitializer() {
 	public void initChannel(SocketChannel ch) throws Exception {
 		ch.pipeline()
                 .addLast("encoder", new HttpResponseEncoder() {
+
+					private ByteBuf encodedHeaders;
+					private HttpHeaders lastSeenHeaders;
+
+					@Override
+					protected void encodeHeaders(HttpHeaders headers, ByteBuf buf) {
+						if (lastSeenHeaders != headers) {
+							updateEncodedHttpHeaders(headers, buf);
+						}
+						encodedHeaders.getBytes(encodedHeaders.readerIndex(), buf, encodedHeaders.readableBytes());
+					}
+
+					private void updateEncodedHttpHeaders(HttpHeaders headers, ByteBuf buf) {
+						if (encodedHeaders == null) {
+							encodedHeaders = Unpooled.buffer(buf.writableBytes());
+						} else {
+							encodedHeaders.clear().ensureWritable(buf.writableBytes());
+						}
+						super.encodeHeaders(headers, encodedHeaders);
+						lastSeenHeaders = headers;
+					}
+
 					@Override
 					public boolean acceptOutboundMessage(final Object msg) throws Exception {
 						if (msg.getClass() == DefaultFullHttpResponse.class) {