maven_jar: Support download of artifacts from Maven snapshot repo

When the repository type is MAVEN_SNAPSHOT, the artifact is downloaded
from the Maven snapshot repository [1].

The artifact ID is given in the form:

 group:name:version:snapshot

where `group`, `name` and `version` are as before, and `snapshot` is
the snapshot timestamp (i.e. '20160407.201829-175').

[1] https://oss.sonatype.org/content/repositories/snapshots/

Change-Id: I992eb1461aa976ccc5137669270abe704f260500

lib/maven.defs

@@ -16,6 +16,7 @@ GERRIT = 'GERRIT:'
 GERRIT_API = 'GERRIT_API:'
 MAVEN_CENTRAL = 'MAVEN_CENTRAL:'
 MAVEN_LOCAL = 'MAVEN_LOCAL:'
+MAVEN_SNAPSHOT = 'MAVEN_SNAPSHOT:'
 
 def define_license(name):
   n = 'LICENSE-' + name
@@ -43,23 +44,48 @@ def maven_jar(
     local_license = False):
   from os import path
 
+  def maven_snapshot(parts):
+    if len(parts) != 4:
+      raise NameError('%s:\nexpected id="groupId:artifactId:version:snapshot]"'
+                      % id)
+    group, artifact, version, snapshot = parts
+    jar = path.join(name,
+      version + '-SNAPSHOT',
+      '-'.join([artifact.lower(), version, snapshot]))
+    url = '/'.join([
+      repository,
+      group.replace('.', '/'),
+      artifact,
+      version + '-SNAPSHOT',
+      '-'.join([artifact.lower(), version, snapshot])])
+    return jar, url
+
+  def maven_release(parts):
+    if len(parts) not in [3, 4]:
+      raise NameError('%s:\nexpected id="groupId:artifactId:version[:classifier]"'
+                      % id)
+    if len(parts) == 4:
+      group, artifact, version, classifier = parts
+      file_version = version + '-' + classifier
+    else:
+      group, artifact, version = parts
+      file_version = version
+
+    jar = path.join(name, artifact.lower() + '-' + file_version)
+    url = '/'.join([
+      repository,
+      group.replace('.', '/'),
+      artifact,
+      version,
+      artifact + '-' + file_version])
+
+    return jar, url
+
   parts = id.split(':')
-  if len(parts) not in [3, 4]:
-    raise NameError('%s:\nexpected id="groupId:artifactId:version[:classifier]"'
-                    % id)
-  if len(parts) == 4:
-    group, artifact, version, classifier = parts
-    file_version = version + '-' + classifier
+  if repository.startswith(MAVEN_SNAPSHOT):
+    jar, url = maven_snapshot(parts)
   else:
-    group, artifact, version = parts
-    file_version = version
-
-  jar = path.join(name, artifact.lower() + '-' + file_version)
-
-  url = '/'.join([
-    repository,
-    group.replace('.', '/'), artifact, version,
-    artifact + '-' + file_version])
+    jar, url = maven_release(parts)
 
   binjar = jar + '.jar'
   binurl = url + '.jar'

tools/util.py

@@ -20,6 +20,7 @@ REPO_ROOTS = {
   'GERRIT_API': 'https://gerrit-api.commondatastorage.googleapis.com/release',
   'MAVEN_CENTRAL': 'http://repo1.maven.org/maven2',
   'MAVEN_LOCAL': 'file://' + path.expanduser('~/.m2/repository'),
+  'MAVEN_SNAPSHOT': 'https://oss.sonatype.org/content/repositories/snapshots',
 }