Generating the sample adapter

To generate the sample adapter, run the following commands:

1. javac Printfile.java

This compiles the Java class.

2. javah -jni PrintFile

This generates the header file, PrintFile.h, displayed below.

JNIEXPORT jint JNICALL
Java_PrintFile_printFile__Ljava_lang_String_2Ljava_lang_String_2
(JNIEnv *, jobject, jstring, jstring);
JNIEXPORT jint JNICALL
Java_PrintFile_printFile__Ljava_lang_String_2(JNIEnv *, jobject, jstring);

3. Implement the native methods. An outline is shown below.

JNIEXPORT jint JNICALL
Java_PrintFile_printFile__Ljava_lang_String_2
    (JNIEnv *env, jobject obj, jstring strFilename)
{    jboolean isCopy;
    const char *filename = (*env)->GetStringUTFChars(env,
    strFilename, &isCopy);

...
    C code to actually print the file
    ...

    if (isCopy == JNI_TRUE)
    (*env)->ReleaseStringUTFChars(env, strFilename, filename);
    return iSuccess;
}