伴随对象Kotlin JNI中的UnsatisfiedLinkError [英] UnsatisfiedLinkError in companion object Kotlin JNI

问题描述

我正在我的一个移动应用程序中将代码从Java转换为Kotlin，并且Java中可用的代码停止在Kotlin中工作.它使用JNI桥来调用C ++代码.

I'm converting code from Java to Kotlin in one of my mobile apps, and the code that worked in Java stopped working in Kotlin. It uses JNI bridge to call C++ code.

Kotlin方法声明:

Kotlin method declaration:

class Converter{  
    companion object {
        external fun convertNative(width: Int, height: Int, row: Int, input: ByteArray, ft: Int, output: ByteArray)
    }
}

.cc代码:

   extern "C" {
    JNIEXPORT void JNICALL OBJECT_TRACKER_METHOD(convertNative)(JNIEnv* env, jobject thiz, jint width, jint height, jint row,
    jbyteArray input, jint ft, jbyteArray output);
}
    JNIEXPORT void JNICALL OBJECT_TRACKER_METHOD(convertNative)(
    JNIEnv* env, jobject thiz, jint width, jint height, jint row,
    jbyteArray input, jint ft, jbyteArray output) {...}

我得到的错误:

java.lang.UnsatisfiedLinkError:No implementation found for void com.sampleapp.Converter$Companion.convertNative(int,int,int,byte[],int,byte[])(tried Java_com_sampleapp_Converter_00024Companion_convertNative and Java_com_sampleapp_Converter_00024Companion_convertNative__III_3BI_3B) at com.sampleapp.Converter$Companion.convertNative(Native Method)...

原始的JAVA方法(可以正常工作)

The original JAVA method (this works fine)

protected static native void convertNative(
      int width, int height, int row, byte[] input, int ft, byte[] output);

在这两种情况下，都可以使用System.loadLibrary(我看到正确的日志输出，没有错误)正确加载该库.

Also the library is properly loaded using System.loadLibrary (I see correct log output, no errors) in both cases.

推荐答案

如果要避免更改C ++代码，应使用@JvmStatic注释Kotlin函数，即:

If you want to avoid changing the C++ code you should annotate the Kotlin function with @JvmStatic, i.e:

@JvmStatic external fun convertNative(width: Int, height: Int, row: Int, input: ByteArray, ft: Int, output: ByteArray)

顺便说一句，您的C ++函数声明在技术上是错误的:对于静态方法，第二个参数是jclass，而不是jobject.

By the way, your C++ function declaration is technically incorrect: For static methods, the second parameter is a jclass, not a jobject.

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