以下一個簡單的 Makefile,示範如何使用 j2objc 和 j2objcc 進行建構:
.SUFFIXES: .java .m
BUILD_DIR = build
SOURCE_DIR = src
# Change to where distribution was unzipped.
J2OBJC_DISTRIBUTION = /your/distribution/dir
J2OBJC = $(J2OBJC_DISTRIBUTION)/j2objc
J2OBJCC = $(J2OBJC_DISTRIBUTION)/j2objcc
OBJECTS = \
$(BUILD_DIR)/foo/MainClass.o \
$(BUILD_DIR)/foo/bar/Support.o \
$(BUILD_DIR)/foo/bar/Utils.o
OBJC_SOURCES = $(OBJECTS:.o=.m)
RESULT = mainclass
default: translate $(OBJECTS)
$(J2OBJCC) -o $(RESULT) $(OBJECTS)
translate: $(BUILD_DIR) $(OBJC_SOURCES)
clean:
@rm -rf $(RESULT) $(BUILD_DIR)
$(BUILD_DIR)/%.m $(BUILD_DIR)/%.h: $(SOURCE_DIR)/%.java
$(J2OBJC) -sourcepath $(SOURCE_DIR) -d $(BUILD_DIR) $?
$(BUILD_DIR)/%.o: $(BUILD_DIR)/%.m
$(J2OBJCC) -I$(BUILD_DIR) -c $? -o $@
$(BUILD_DIR):
@mkdir $(BUILD_DIR)
這項功能可以正常運作,但由於原始來源檔案會分開翻譯,因此翻譯速度很慢。 和 javac 一樣,由於只要剖析原始碼一次,就能一次將所有相關檔案一併轉譯。下列變更可大幅縮短建構時間:
JAVA_SOURCES = $(TMPDIR).sources.list
translate: pre_translate $(OBJC_SOURCES)
@if [ `cat $(JAVA_SOURCES) | wc -l` -ge 1 ] ; then \
$(J2OBJC) -sourcepath $(SOURCE_DIR) -d $(BUILD_DIR) \
`cat $(JAVA_SOURCES)` ; \
fi
pre_translate: $(BUILD_DIR)
@rm -f $(JAVA_SOURCES)
@touch $(JAVA_SOURCES)
$(BUILD_DIR)/%.m $(BUILD_DIR)/%.h: $(SOURCE_DIR)/%.java
@echo $? >> $(JAVA_SOURCES)