More flexibility to keep/remove R.class in static Java library

- Usually you don't need to set LOCAL_JAR_EXCLUDE_FILES in your
  Android.mk, if your static library is directly used by an app.
- If your library will be included by another library that need
  reference the R/Manifest class, you can set
  LOCAL_JAR_EXCLUDE_FILES := none
  to keep the generated classes.
- If your library includes another static library that has Android
  resource and you want to remove the generated classes carried by
  the static library, set:
  LOCAL_JAR_EXCLUDE_FILES := $(ANDROID_RESOURCE_GENERATED_CLASSES)

With the LOCAL_JAR_EXCLUDE_FILES value "none", deprecate the old
long variable LOCAL_KEEP_R_CLASS_IN_STATIC_JAVA_LIBRARY.

Change-Id: I3b9ad5d66f0262f784feb09bc1537c5b01256258

core/clear_vars.mk

@@ -122,9 +122,7 @@ LOCAL_CTS_TEST_PACKAGE:=
 LOCAL_CTS_TEST_RUNNER:=
 LOCAL_CLANG:=
 LOCAL_ADDRESS_SANITIZER:=
-# Whether to keep the generated R/Manifest classes when building static Java library
-# with Android resource. false(default), or true
-LOCAL_KEEP_R_CLASS_IN_STATIC_JAVA_LIBRARY:=
+LOCAL_JAR_EXCLUDE_FILES:=
 
 # Trim MAKEFILE_LIST so that $(call my-dir) doesn't need to
 # iterate over thousands of entries every time.

core/definitions.mk

@@ -81,6 +81,10 @@ ALL_FINDBUGS_FILES:=
 # GPL module license files
 ALL_GPL_MODULE_LICENSE_FILES:=
 
+# Generated class file names for Android resource.
+# They are escaped and quoted so can be passed safely to a bash command.
+ANDROID_RESOURCE_GENERATED_CLASSES := 'R.class' 'R$$*.class' 'Manifest.class' 'Manifest$$*.class'
+
 ###########################################################
 ## Debugging; prints a variable list to stdout
 ###########################################################
@@ -1515,6 +1519,10 @@ fi
 $(hide) rm -f $(PRIVATE_CLASS_INTERMEDIATES_DIR)/java-source-list
 $(hide) rm -f $(PRIVATE_CLASS_INTERMEDIATES_DIR)/java-source-list-uniq
 $(hide) rm -f $@
+$(if $(PRIVATE_JAR_EXCLUDE_FILES), $(hide) find $(PRIVATE_CLASS_INTERMEDIATES_DIR) \
+    -name $(word 1, $(PRIVATE_JAR_EXCLUDE_FILES)) \
+    $(addprefix -o -name , $(wordlist 2, 999, $(PRIVATE_JAR_EXCLUDE_FILES))) \
+    | xargs rm -rf)
 $(hide) jar $(if $(strip $(PRIVATE_JAR_MANIFEST)),-cfm,-cf) \
     $@ $(PRIVATE_JAR_MANIFEST) -C $(PRIVATE_CLASS_INTERMEDIATES_DIR) .
 $(hide) mv $(PRIVATE_CLASS_INTERMEDIATES_DIR)/newstamp $(PRIVATE_CLASS_INTERMEDIATES_DIR)/stamp

core/static_java_library.mk

@@ -36,14 +36,18 @@ all_resources := $(strip \
     ))
 
 ifneq (,$(all_resources))
-# Those files will be excluded from the built jar.
-# The R/Manifest classes should be re-generated in the app Module instead.
-# Use '' and $ escape because they will be passed to bash.
-ifneq (true,$(LOCAL_KEEP_R_CLASS_IN_STATIC_JAVA_LIBRARY))
-LOCAL_JAR_EXCLUDE_FILES := 'R.class' 'R$$*.class' 'Manifest.class' 'Manifest$$*.class'
-endif
+# By default we should remove the R/Manifest classes from a static Java library,
+# because they will be regenerated in the app that uses it.
+# But if the static Java library will be used by a library, then we may need to
+# keep the generated classes with "LOCAL_JAR_EXCLUDE_FILES := none".
+ifndef LOCAL_JAR_EXCLUDE_FILES
+LOCAL_JAR_EXCLUDE_FILES := $(ANDROID_RESOURCE_GENERATED_CLASSES)
 endif
+ifeq (none,$(LOCAL_JAR_EXCLUDE_FILES))
+LOCAL_JAR_EXCLUDE_FILES :=
 endif
+endif  # all_resources
+endif  # LOCAL_RESOURCE_DIR
 
 include $(BUILD_SYSTEM)/java_library.mk
 
@@ -107,4 +111,3 @@ endif
 endif  # $(all_resources) not empty
 
 LOCAL_IS_STATIC_JAVA_LIBRARY :=
-LOCAL_JAR_EXCLUDE_FILES :=