quick sketch of java/io/*

classpath/java/io/BufferedOutputStream.java

@@ -0,0 +1,51 @@
+package java.io;
+
+public class BufferedOutputStream extends OutputStream {
+  private final OutputStream out;
+  private final byte[] buffer;
+  private int position;
+
+  public BufferedOutputStream(OutputStream out, int size) {
+    this.out = out;
+    this.buffer = new byte[size];
+  }
+  
+  public BufferedOutputStream(OutputStream out) {
+    this(out, 4096);
+  }
+  
+  private void drain() throws IOException {
+    if (position > 0) {
+      out.write(buffer, 0, position);
+      position = 0;
+    }
+  }
+
+  public void write(int c) throws IOException {
+    if (position >= buffer.length) {
+      drain();
+    }
+
+    buffer[position++] = (byte) (c & 0xFF);
+  }
+
+  public void write(byte[] b, int offset, int length) throws IOException {
+    if (length > buffer.length - position) {
+      drain();
+      out.write(b, offset, length);      
+    } else {
+      System.arraycopy(b, offset, buffer, position, length);
+      position += length;
+    }
+  }
+
+  public void flush() throws IOException {
+    drain();
+    out.flush();
+  }
+
+  public void close() throws IOException {
+    flush();
+    out.close();
+  }
+}