Add support for generating jars from protos and add cacheinvalidation_java.

build/protoc_java.py

+#!/usr/bin/env python
+# Copyright (c) 2012 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""Generate java source files from protobufs
+
+Usage:
+    protoc_java.py {protoc} {proto_path} {java_out} {stamp_file} {proto_files}
+
+This is a helper file for the genproto_java action in protoc_java.gypi.
+
+It performs the following steps:
+1. Deletes all old sources (ensures deleted classes are not part of new jars).
+2. Creates source directory.
+3. Generates Java files using protoc.
+4. Creates a new stamp file.
+"""
+
+import os
+import shutil
+import subprocess
+import sys
+
+def main(argv):
+  if len(argv) < 5:
+    usage()
+    return 1
+
+  protoc_path, proto_path, java_out, stamp_file = argv[1:5]
+  proto_files = argv[5:]
+
+  # Delete all old sources
+  if os.path.exists(java_out):
+    shutil.rmtree(java_out)
+
+  # Create source directory
+  os.makedirs(java_out)
+
+  # Generate Java files using protoc
+  ret = subprocess.call(
+      [protoc_path, '--proto_path', proto_path, '--java_out', java_out]
+      + proto_files)
+
+  if ret == 0:
+    # Create a new stamp file
+    with file(stamp_file, 'a'):
+      os.utime(stamp_file, None)
+
+  return ret
+
+def usage():
+  print(__doc__);
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv))