Question

我试图通过插入日志消息来调试JNI C函数，但我无法使其工作。首先，我只想修改Android Studio附带的hello-jni示例。这是修改后的代码：

#include <string.h>
#include <jni.h>
#include <android/log.h>

jstring
Java_com_example_hellojni_HelloJni_stringFromJNI( JNIEnv* env,
                                              jobject thiz )
{
#if defined(__arm__)
    #if defined(__ARM_ARCH_7A__)
    #if defined(__ARM_NEON__)
      #if defined(__ARM_PCS_VFP)
        #define ABI "armeabi-v7a/NEON (hard-float)"
      #else
        #define ABI "armeabi-v7a/NEON"
      #endif
    #else
      #if defined(__ARM_PCS_VFP)
        #define ABI "armeabi-v7a (hard-float)"
      #else
        #define ABI "armeabi-v7a"
      #endif
    #endif
  #else
   #define ABI "armeabi"
  #endif
#elif defined(__i386__)
   #define ABI "x86"
#elif defined(__x86_64__)
   #define ABI "x86_64"
#elif defined(__mips64)  /* mips64el-* toolchain defines __mips__ too */
   #define ABI "mips64"
#elif defined(__mips__)
   #define ABI "mips"
#elif defined(__aarch64__)
   #define ABI "arm64-v8a"
#else
   #define ABI "unknown"
#endif

    __android_log_write(ANDROID_LOG_ERROR, "TEST_TAG", "Error here");

    return (*env)->NewStringUTF(env, "Hello from JNI !  Compiled with ABI " ABI ".");
}

这是我的Android.mk文件：

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_MODULE    := hello-jni
LOCAL_SRC_FILES := hello-jni.c
LOCAL_LDFLAGS := -llog

include $(BUILD_SHARED_LIBRARY)

当我使用ndk-build脚本时，libhello-jni.so文件构建没问题。当我尝试在Android Studio中构建项目时，我收到以下gradle错误消息

Information:Gradle tasks [:app:assembleDebug]
:app:preBuild
:app:compileDebugNdk
C:\Android\projects\hello-jni\app\build\intermediates\ndk\debug\obj/local/arm64-v8a/objs/hello-jni/C_\Android\projects\hello-jni\app\src\main\jni\hello-jni.o: In function `Java_com_example_hellojni_HelloJni_stringFromJNI':
hello-jni.c:(.text.Java_com_example_hellojni_HelloJni_stringFromJNI+0x24): undefined reference to `__android_log_write'
Error:error: ld returned 1 exit status
make.exe: *** [C:\Android\projects\hello-jni\app\build\intermediates\ndk\debug\obj/local/arm64-v8a/libhello-jni.so] Error 1
Error:Execution failed for task ':app:compileDebugNdk'.
> com.android.ide.common.internal.LoggedErrorException: Failed to run command:
C:\Android\android-ndk-r10c\ndk-build.cmd NDK_PROJECT_PATH=null APP_BUILD_SCRIPT=C:\Android\projects\hello-jni\app\build\intermediates\ndk\debug\Android.mk APP_PLATFORM=android-19 NDK_OUT=C:\Android\projects\hello-jni\app\build\intermediates\ndk\debug\obj NDK_LIBS_OUT=C:\Android\projects\hello-jni\app\build\intermediates\ndk\debug\lib APP_ABI=all
Error Code:
2
Output:
C:\Android\projects\hello-jni\app\build\intermediates\ndk\debug\obj/local/arm64-v8a/objs/hello-jni/C_\Android\projects\hello-jni\app\src\main\jni\hello-jni.o: In function `Java_com_example_hellojni_HelloJni_stringFromJNI':
hello-jni.c:(.text.Java_com_example_hellojni_HelloJni_stringFromJNI+0x24): undefined reference to `__android_log_write'
collect2.exe: error: ld returned 1 exit status
make.exe: *** [C:\Android\projects\hello-jni\app\build\intermediates\ndk\debug\obj/local/arm64-v8a/libhello-jni.so] Error 1
Information:BUILD FAILED
Information:Total time: 3.297 secs
Information:2 errors
Information:0 warnings
Information:See complete output in console

我已尝试过此问题中提出的建议，但我仍然遇到同样的错误：What is the Log API to call from an Android JNI program?

我做错了什么？

我使用的是Android Studio 0.8.9和NDK r10c。

Answer 1

经过一番搜索，我找到了答案。

如果我使用命令行上的ndk-build脚本构建.so文件并添加

sourceSets.main {
    jni.srcDirs = []
    jniLibs.srcDir 'src/main/libs'
}

进入我的build.gradle文件，因此gradle没有尝试构建.so文件然后工作。看起来Android Studio-Gradle-NDK集成存在问题？

我在这里找到了答案https://stackoverflow.com/a/21111458/4182796

Answer 2

丑陋的解决方法是删除函数调用并重建源代码，只需在include：

之后添加它

#if 1
#undef __android_log_print
#define __android_log_print(...) {}
#endif

Android NDK - Android studio gradle对__android_log_write的未定义引用

2 个答案: