Question

1）image_api.h定义了以下方法 - int process_image（const char * svgData，void ** mapData）;

2）现在我需要调用此方法并将正确的值传递给从image_api.so文件加载的process_image

- 在JNI C包装器代码中创建void **实例的正确方法是什么？

3）

JNIEXPORT jint JNICALL Java_JNITest_process_image(JNIEnv *env, jstring svgData, jobject mapData, jint status) {

    const char *str;
    str = (*env)->GetStringUTFChars(env, svgData, NULL);
    **status = process_image(str,  (void**)&mapData);** 

return status;
}

////////////

我在调用process_image时遇到UnsatisfiedLinkError，因为方法签名不匹配

Answer 1

在您的代码中

JNIEXPORT jint JNICALL 
Java_JNITest_process_image(JNIEnv *env, 
    jstring svgData, 
    jobject mapData, // this is some Java object, you need to access it
                     // take a look here: 
                     // http://jnicookbook.owsiak.org/recipe-No-020/
    jint status      // you don't need that, and you can't return value
                     // like this in JNI
    ) {

    const char *str;
    str = (*env)->GetStringUTFChars(env, svgData, NULL);
    // Question is ... what exactly process_image does?
    // without any additional knowledge about process_image
    // it is hard to guess what goes here
    int status = process_image(str, &pointer_to_some_memory_region ); 
    return status;
}

如何从JNI C代码传递void **到C库？

1 个答案: