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Question

我正在尝试为 Android 编译 Taglib。我已经下载了最新版本 Taglib 来自 here 。在为arm-linux build 编译后，我已成功将其导入到我的应用程序中，但是当我尝试从tag_c.h 调用任何函数时，出现以下错误：

SharedLibrary  : taglibwav.so
/home/test/workspacenew/Androidtaglibexample/obj/local/armeabi/
objs/squared/taglibwav.o: In function 
`Java_com_android_androidtag_WavFileDetails_taglibwav':
/home/test/workspacenew/Androidtaglibexample/jni/taglibwav.c:30: 
undefined reference to `taglib_set_strings_unicode'
collect2: ld returned 1 exit status
make: *** [/home/test/workspacenew/Androidtaglibexample/obj/
local/armeabi/taglibwav.so] Error 1

应用配置信息为：

标签库 ./configure :-

./configure CC="/home/hcl/taglib/taglib/toolchain/bin/arm-linux-androideabi-gcc"\
--host="arm-linux" \
--build="arm" \
--enable-static="no" \
--enable-shared="yes" \
--prefix="/home/test/workspacenew/Androidtaglibexample/jni/testtaglib/"\

Android.mk :-

LOCAL_PATH := $(call my-dir)

#declare the prebuilt library
include $(CLEAR_VARS)
LOCAL_MODULE := taglibtest
LOCAL_SRC_FILES := testtaglib/lib/libtag.a
LOCAL_EXPORT_C_INCLUDES := testtaglib/include/taglib/
LOCAL_PRELINK_MODULE := true
include $(PREBUILT_STATIC_LIBRARY)

include $(CLEAR_VARS) 
include $(call all-subdir-makefiles)
LOCAL_MODULE := taglibwav
LOCAL_SRC_FILES := taglibwav.c
LOCAL_C_INCLUDES := $(LOCAL_PATH)/testtaglib/include/taglib/
LOCAL_SHARED_LIBRARY := taglibtest
LOCAL_LDLIBS    := -llog -ljnigraphics -lz -lm -L$(SYSROOT)/usr/lib -llog 
include $(BUILD_SHARED_LIBRARY)

---

Application.mk :-

APP_ABI :=armeabi
APP_STL:=stlport_static

---

taglibwav.c :-

#include <jni.h>
#include <tag_c.h>
#include <android/log.h>
#ifndef FALSE
#define FALSE 0
#endif
.......
.......
JNIEXPORT void JNICALL Java_com_android_androidtag_WavFileDetails_taglibwav
  (JNIEnv * ev, jclass jc){
      int i;
      int seconds;
      int minutes;
      TagLib_File *file;  //<< accessed form tag_c.h : OK
      TagLib_Tag *tag;    //<< accessed form tag_c.h : OK
      const TagLib_AudioProperties *properties; //<<accessed form tag_c.h : OK
      taglib_set_strings_unicode(FALSE);//<<accessed form tag_c.h : GETTING ERROR
}
....
....

Android NDK 版本：- Android-Ndk-r7c

请指导我正确的方向来解决我做错的事情

Answer 1

您需要同时链接tag_c.h.o 和taglibwav.o：

gcc -o program tag_c.h taglibwav.c

Answer 2

LOCAL_STATIC_LIBRARY := taglibtest

您使用的是静态库，而不是共享库。使用 shared 的指令会混淆构建环境。

Answer 3

为了完成工作，我会修改 tag_c.h at line 43 来定义正确的 visibility 规则：

#define TAGLIB_C_EXPORT __attribute__ ((visibility("default")))

如果可行，您可以open a bug at taglib 并链接回此问题。

Answer 4

  TagLib_File *file;  //<< accessed form tag_c.h : OK
  TagLib_Tag *tag;    //<< accessed form tag_c.h : OK
  const TagLib_AudioProperties *properties; //<<accessed form tag_c.h : OK
  taglib_set_strings_unicode(FALSE);//<<accessed form tag_c.h : GETTING ERROR

你无法访问taglib_set_strings_unicode的原因是因为TAGLIB_C_EXPORT在tag_c.h中是如何定义的。

#if defined(_WIN32) || defined(_WIN64)
#ifdef MAKE_TAGLIB_C_LIB
#define TAGLIB_C_EXPORT __declspec(dllexport)
#else
#define TAGLIB_C_EXPORT __declspec(dllimport)
#endif
#elif defined(__GNUC__) && (__GNUC__ > 4 || __GNUC__ == 4 && __GNUC_MINOR__ >= 1)
#define TAGLIB_C_EXPORT __attribute__ ((visibility("default")))
#else
#define TAGLIB_C_EXPORT
#endif
...
typedef struct { int dummy; } TagLib_File;
typedef struct { int dummy; } TagLib_Tag;
typedef struct { int dummy; } TagLib_AudioProperties;
...
TAGLIB_C_EXPORT void taglib_set_strings_unicode(BOOL unicode);
...

Answer 5

我想你可能需要-ltag_c 在某个地方