Android无法找到ndk方法实现

Question

没有实施问题

我在Android上使用C ++和Java之间的桥梁，用于扫描android中的文件 所以我有疑问，我有错误

No implementation found for void com.example.Scanner.scan(java.lang.String) (tried Java_com_example_Scanner_scan and Java_com_example_Scanner_scan__Ljava_lang_String_2)

扫描仪文件来源

public class Scanner extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        scan("sdcard/");
    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {

        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();
        if (id == R.id.action_settings) {
            return true;
        }
        return super.onOptionsItemSelected(item);
    }

    native void scan(String path);

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

}

scanner.cpp

void Java_com_example_Scanner_scan(JNIEnv* env, jclass cls, jstring path)
{
    mJNI = env;
    mObject = cls;

    const char *scan_path = mJNI->GetStringUTFChars(path, 0);

    scan(string(scan_path));

    // Release string IMPORTANT For Java & C++
    mJNI->ReleaseStringUTFChars(path, scan_path);
}

Answer 1

你忘记了JNIexport和JNIcall。 这就是它应该是这样的：

JNIEXPORT void JNICALL Java_ClassName_MethodName
  (JNIEnv *env, jobject obj)
{
    /*Implement Native Method Here*/
}

所以对你来说应该是：

JNIEXPORT void JNICALL Java_com_example_Scanner_scan(JNIEnv* env, jclass cls, jstring path)
{
//do you things
}

您可以在此处找到一些不错的信息：wiki