Android连接C模块与C++应用程序

Question

这是我的完整Android.mk文件，当我试图构建这个文件时，我会遇到一个链接器问题(请参阅下面)

LOCAL_PATH := $(call my-dir)

#
# Opus - low-latency audio codec
#

include $(CLEAR_VARS)
LOCAL_DIR := opus-1.0.3
LOCAL_MODULE := opus

LOCAL_CELT_SOURCES :=   \
    $(LOCAL_DIR)/celt/bands.c \
    ...

LOCAL_SILK_SOURCES :=   \
    $(LOCAL_DIR)/silk/CNG.c \
    ...

LOCAL_SILK_SOURCES_FIXED := \
    $(LOCAL_DIR)/silk/fixed/LTP_analysis_filter_FIX.c \
    ...

LOCAL_SILK_SOURCES_FLOAT := \
    $(LOCAL_DIR)/silk/float/apply_sine_window_FLP.c \
    ...

LOCAL_OPUS_SOURCES := \
    $(LOCAL_DIR)/src/opus.c \
    ...

LOCAL_CFLAGS := -DNONTHREADSAFE_PSEUDOSTACK

LOCAL_C_INCLUDES := \
    $(LOCAL_DIR)/include \
    $(LOCAL_DIR)/celt \
    $(LOCAL_DIR)/silk \
    $(LOCAL_DIR)/silk/fixed \
    $(LOCAL_DIR)/silk/float

LOCAL_SRC_FILES := $(LOCAL_CELT_SOURCES) \
    $(LOCAL_SILK_SOURCES) \
    $(LOCAL_SILK_SOURCES_FIXED) \
    $(LOCAL_SILK_SOURCES_FLOAT)

LOCAL_EXPORT_C_INCLUDES := $(LOCAL_DIR)/include

include $(BUILD_STATIC_LIBRARY)

################

include $(CLEAR_VARS)

LOCAL_MODULE    := audio-client-jni

LOCAL_SRC_FILES := audio-client-jni.cpp

# low latency codec
LOCAL_STATIC_LIBRARIES += opus

# for native audio
LOCAL_LDLIBS    += -lOpenSLES

# for logging
LOCAL_LDLIBS    += -llog

# for native asset manager
LOCAL_LDLIBS    += -landroid

include $(BUILD_SHARED_LIBRARY)

为了排除opus的构建方式存在问题，我使用了一个不同的构建系统(称为冻土带)来完成完全相同的工作，并且它在使用MSVC++的Windows上非常复杂。

下面是链接器命令和错误(为了提高可读性，我格式化了命令行)

C:/Projects/android-ndk-r8e/toolchains/arm-linux-androideabi-4.6/prebuilt/windows-x86_64/bin/arm-linux-androideabi-g++
    -Wl,-soname,libaudio-client-jni.so 
    -shared
    --sysroot=C:/Projects/android-ndk-r8e/platforms/android-14/arch-arm
    C:/Projects/workspace/AudioClient//obj/local/armeabi/objs/audio-client-jni/audio-client-jni.o
    C:/Projects/workspace/AudioClient//obj/local/armeabi/libopus.a
    C:/Projects/workspace/AudioClient//obj/local/armeabi/libstdc++.a
    -lgcc
    -no-canonical-prefixes
    -Wl,--no-undefined
    -Wl,-z,noexecstack
    -Wl,-z,relro
    -Wl,-z,now
    -LC:/Projects/android-ndk-r8e/platforms/android-14/arch-arm/usr/lib
    -lOpenSLES
    -llog
    -landroid
    -lstdc++
    -lc
    -lm
    -o C:/Projects/workspace/AudioClient//obj/local/armeabi/libaudio-client-jni.so

错误跟随

C:/Projects/android-ndk-r8e/toolchains/arm-linux-androideabi-4.6/prebuilt/windows-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld.exe: C:/Projects/workspace/AudioClient//obj/local/armeabi/objs/audio-client-jni/audio-client-jni.o: in function (anonymous namespace)::AuClient::ReceiveThenEnqueue():C:/Projects/workspace/AudioClient//jni/audio-client-jni.cpp:419: error: undefined reference to 'opus_decode'
C:/Projects/android-ndk-r8e/toolchains/arm-linux-androideabi-4.6/prebuilt/windows-x86_64/bin/../lib/gcc/arm-linux-androideabi/4.6/../../../../arm-linux-androideabi/bin/ld.exe: C:/Projects/workspace/AudioClient//obj/local/armeabi/objs/audio-client-jni/audio-client-jni.o: in function InitializeThread:C:/Projects/workspace/AudioClient//jni/audio-client-jni.cpp:387: error: undefined reference to 'opus_decoder_create'

我需要第二双眼睛来观察这个问题，它明确地在audio-client-jni.o之前链接libopus.a，但如果这是我不知道如何修改makefile以获得所需结果的问题。当包含在C++应用程序中时，opus.hAPI是用extern "C“定义的。到目前为止还没有运气。

Answer 1

感谢@AlexCohn的协助，显然没有任何问题，相反，所有的源文件都没有适当地包括，轻微忽视了我的部分。

在我的例子中，我不确定应该如何设置东西才能运行bin util命令，幸运的是，它非常简单：

"C:\Projects\android-ndk-r8e\toolchains\arm-linux-androideabi-4.6\prebuilt\windows-x86_64\bin\arm-linux-androideabi-nm.exe" "C:\Projects\workspace\AudioClient\obj\local\armeabi\libopus.a"

我只是从预先构建的工具链中挑选了一些看似合理的东西。

有了nm的输出，我可以验证出口是否在那里。经过仔细检查后，我发现我忘了把$(LOCAL_OPUS_SOURCES)包括在我的LOCAL_C_INCLUDES中。解决这个问题。