使用本机库（仅限 C，无 C++），但未找到实现

Question

尝试在 android 和 AFAIK 上使用 this lib 的作品，链接和 .so 看起来不错。

调用 C 函数时出错（我关注了these intstructs）

D/OpusRecorder( 1964): Start recording!
E/art     ( 1964): No implementation found for int com.droidkit.opus.OpusLib.startRecord(java.lang.String) (tried Java_com_droidkit_opus_OpusLib_startRecord and Java_com_droidkit_opus_OpusLib_startRecord__Ljava_lang_String_2)
E/AndroidRuntime( 1964): FATAL EXCEPTION: Thread-8227
E/AndroidRuntime( 1964): Process: com.borneo.speech, PID: 1964
E/AndroidRuntime( 1964): java.lang.UnsatisfiedLinkError: No implementation found for int com.droidkit.opus.OpusLib.startRecord(java.lang.String) (tried Java_com_droidkit_opus_OpusLib_startRecord and Java_com_droidkit_opus_OpusLib_startRecord__Ljava_lang_String_2)
E/AndroidRuntime( 1964):    at com.droidkit.opus.OpusLib.startRecord(Native Method)
E/AndroidRuntime( 1964):    at com.borneo.speech.OpusRecorder.run(OpusRecorder.java:439)
W/ActivityManager(  724):   Force finishing activity 1 com.borneo.speech/.Speech_API_Activity

.so被打包在apk中

函数存在于 .so 中，Type="T"...

aar$ nm -D libopus.so | head
000084c1 T Java_com_droidkit_opus_OpusLib_closeOpusFile
000084c5 T Java_com_droidkit_opus_OpusLib_isOpusFile
00008491 T Java_com_droidkit_opus_OpusLib_openOpusFile
00008471 T Java_com_droidkit_opus_OpusLib_readOpusFile
00008489 T Java_com_droidkit_opus_OpusLib_seekOpusFile
00008145 T Java_com_droidkit_opus_OpusLib_startRecord ***

---CL 语言详细信息---

用 C 语言实现：

audio.c

#include "com_droidkit_opus_OpusLib.h"   <-- from the Java class=com.droidkit.opus.OpusLib via javah

//rev belo per @Nicklas

JNIEXPORT jint JNICALL Java_com_droidkit_opus_OpusLib_startRecord(JNIEnv *env, jobject javaThis, jstring path) {
    const char *pathStr = (*env)->GetStringUTFChars(env, path, 0);

    int result = initRecorder(pathStr);

    if (pathStr != 0) {
        (*env)->ReleaseStringUTFChars(env, path, pathStr);
    }

    return result;
}

c 标题...

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class com_droidkit_opus_OpusLib */

#ifndef _Included_com_droidkit_opus_OpusLib
#define _Included_com_droidkit_opus_OpusLib
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     com_droidkit_opus_OpusLib
 * Method:    startRecord
 * Signature: (Ljava/lang/String;)I
 */
JNIEXPORT jint JNICALL Java_com_droidkit_opus_OpusLib_startRecord
  (JNIEnv *, jobject, jstring);

/*
 * Class:     com_droidkit_opus_OpusLib
 * Method:    writeFrame
 * Signature: (Ljava/nio/ByteBuffer;I)I
 */
JNIEXPORT jint JNICALL Java_com_droidkit_opus_OpusLib_writeFrame
  (JNIEnv *, jobject, jobject, jint);

/*
 * Class:     com_droidkit_opus_OpusLib
 * Method:    stopRecord
 * Signature: ()V
 */
JNIEXPORT void JNICALL Java_com_droidkit_opus_OpusLib_stopRecord
  (JNIEnv *, jobject);

/*
 * Class:     com_droidkit_opus_OpusLib
 * Method:    isOpusFile
 * Signature: (Ljava/lang/String;)I
 */
JNIEXPORT jint JNICALL Java_com_droidkit_opus_OpusLib_isOpusFile
  (JNIEnv *, jobject, jstring);

...
#ifdef __cplusplus
}
#endif
#endif

===JAVA 详细信息调用 C===

==EDITED== Java Native Decl.

/**
 * OpusLib native binding
 */
public class OpusLib {

    static {
        System.loadLibrary("opus");
    }

    /**
     * Starting opus recording
     *
     * @param path path to file
     * @return non zero if started player
     */
    public native int startRecord(String path);


    /**
     * Writing audio frame to encoder
     *
     * @param frame buffer with sound in 16 bit mono PCM 16000 format
     * @param len   len of data
     * @return not null if successful
     */
    public native int writeFrame(ByteBuffer frame, int len);

    /**
     * Stopping record
     */
    public native void stopRecord();

    /**
     * Checking Opus File format
     *
     * @param path path to file
     * @return non zero if opus file
     */
    public native int isOpusFile(String path);

    /**
     * Opening file
     *
     * @param path path to file
     * @return non zero if successful
     */
    public native int openOpusFile(String path);

    /**
     * Seeking in opus file
     *
     * @param position position in file
     * @return non zero if successful
     */
    public native int seekOpusFile(float position);

    /**
     * Closing opus file
     */
    public native void closeOpusFile();

    /**
     * Reading from opus file
     *
     * @param buffer
     * @param capacity
     */
    public native void readOpusFile(ByteBuffer buffer, int capacity);

    /**
     * Is playback finished
     *
     * @return non zero if playback is finished
     */
    public native int getFinished();

    /**
     * Read block size in readOpusFile
     *
     * @return block size in bytes
     */
    public native int getSize();

    /**
     * Offset of actual sound for playback
     *
     * @return offset
     */
    public native long getPcmOffset();

    /**
     * Total opus pcm duration
     *
     * @return pcm duration
     */
    public native long getTotalPcmDuration();

}

        try {
            opus = new OpusLib();
        }catch(UnsatisfiedLinkError ulx) {
            Log.e(LTAG, "Illegal native Load: " + ulx.getMessage());
        }

...
public class OpusLib {
    static {
        System.loadLibrary("opus");
    }   

AFAIK，lib 加载正常

UnsatisfiedLink Excp 出现在下面的最后一行：

私有字符串 mPath = 路径；

   if (mShouldRecord)            
       int mint = opus.startRecord(mPath);     <-- throws unsatisfiedLink - no implementation found   

startRecord 在符号表中，尽管我不确定所有函数参数类型都匹配吗？见“string_2”...

startRecord__Ljava_lang_String_2)

==== 构建信息 Gradle 和linkedit ===

link :
command: /usr/local/src/android-ndk-r10d/ndk-build NDK_PROJECT_PATH=null APP_BUILD_SCRIPT=/home/rob/src/tmp/speechnw/libraries/opus/build/intermediates/ndk/release/Android.mk APP_PLATFORM=android-19 NDK_OUT=/home/rob/src/tmp/speechnw/libraries/opus/build/intermediates/ndk/release/obj NDK_LIBS_OUT=/home/rob/src/tmp/speechnw/libraries/opus/build/intermediates/ndk/release/lib APP_STL=stlport_static APP_ABI=armeabi-v7a

[armeabi-v7a] Compile thumb  : opus <= audio.c                       
...
[armeabi-v7a] SharedLibrary  : libopus.so
[armeabi-v7a] Install        : libopus.so => /home/rob/src/tmp/speechnw/libraries/opus/build/intermediates/ndk/release/lib/armeabi-v7a/libopus.so

build.gradle

默认配置 { minSdkVersion 8 targetSdkVersion 19 版本代码 1 版本名称“1.1.1”

ndk {
    moduleName "opus"

    cFlags "-DANDROID_NDK " +
            "-DDISABLE_IMPORTGL " +
            "-w -std=gnu99 -O3 -fno-strict-aliasing -fprefetch-loop-arrays " +
            "-DNULL=0 -DSOCKLEN_T=socklen_t -DLOCALE_NOT_USED -D_LARGEFILE_SOURCE=1 -D_FILE_OFFSET_BITS=64 "+
            "-Drestrict='' -D__EMX__ -DOPUS_BUILD -DFIXED_POINT -DUSE_ALLOCA -DHAVE_LRINT -DHAVE_LRINTF -fno-math-errno "
            "-DAVOID_TABLES "
    ldLibs "log", "m"
    stl "stlport_static"
    abiFilter "armeabi-v7a"
}

}

Answer 1

替换这一行：

JNIEXPORT jint JNICALL Java_com_droidkit_opus_OpusLib_startRecord(JNIEnv *env, jclass class, jstring path) {

与：

JNIEXPORT jint JNICALL Java_com_droidkit_opus_OpusLib_startRecord(JNIEnv *env, jobject javaThis, jstring path) {

您在 C 中定义的函数映射到 Java 中的静态方法，但在 Java 中您将其用作实例方法。我替换的是：jclass class, 在你的 C 函数签名中带有 jobject javaThis,。另请注意，在您的 C 标头中，您还声明了带有实例方法签名的函数，正如您似乎想要的那样。