--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/cachingfilter/ProxyServletOutputStream.java	Thu Mar 21 19:15:52 2019 -0600
@@ -0,0 +1,72 @@
+package cachingfilter;
+
+import java.io.IOException;
+import java.io.OutputStream;
+import java.io.ByteArrayOutputStream;
+import javax.servlet.ServletOutputStream;
+
+
+public abstract class ProxyServletOutputStream extends ServletOutputStream {
+	private static final int BUFFER_SIZE = 100;
+
+	private OutputStream out = new OutputStream() {
+		private final ByteArrayOutputStream buf = new ByteArrayOutputStream();
+
+		public void write(int b) throws IOException {
+			buf.write(b);
+			check();
+		}
+		
+		public void write(byte b[]) throws IOException {
+			buf.write(b);
+			check();
+		}
+		
+		public void write(byte b[], int off, int len) throws IOException {
+			buf.write(b,off,len);
+			check();
+		}
+		
+		public void flush() throws IOException {
+			setOut();
+			out.flush();
+		}
+		
+		public void close() throws IOException {
+			setOut();
+			out.close();
+		}
+
+		void check() throws IOException {
+			if( buf.size() >= BUFFER_SIZE )
+				setOut();
+		}
+
+		private void setOut() throws IOException {
+			out = newOutputStream();
+			out.write(buf.toByteArray());
+		}
+	};
+
+	protected abstract OutputStream newOutputStream() throws IOException;
+	
+	public void write(int b) throws IOException {
+		out.write(b);
+	}
+	
+	public void write(byte b[]) throws IOException {
+		out.write(b);
+	}
+	
+	public void write(byte b[], int off, int len) throws IOException {
+		out.write(b,off,len);
+	}
+	
+	public void flush() throws IOException {
+		out.flush();
+	}
+	
+	public void close() throws IOException {
+		out.close();
+	}
+}