从 JNI 调用 Android 上的非静态方法

发布于 2024-12-07 19:03:24 字数 545 浏览 0 评论 0原文

我想使用 JNI 在 Android 上调用非静态方法。我可以使用 CallStaticVoidMethod 调用静态方法。为了调用非静态方法，我使用了 CallVoidMethod。它不起作用。

谁能告诉我从 JNI 调用 Android 的非静态方法的正确代码吗？

jmethodID method = env->GetMethodID(gJniRefCached.ImsFwkLoaderClass, "DispVideo", "([BII)V");

env->CallVoidMethod(gJniRefCached.ImsFwkLoaderClass, 方法,arr,宽度,高度);

我也尝试过使用代码是的类的对象 jclass cls = env->GetObjectClass(obj); jmethodID method = env->GetMethodID(cls, "DispVideo", "([BII)V"); env->CallVoidMethod(cls, method,arr,width,height);

原文

I want to call a non-static method on Android using JNI. I can call static methods using CallStaticVoidMethod. To call non-static methods, I have used CallVoidMethod. It is not working.

Can anybody please tell me correct code to call nonStatic method of Android From JNI?

jmethodID method = env->GetMethodID(gJniRefCached.ImsFwkLoaderClass, "DispVideo", "([BII)V");

env->CallVoidMethod(gJniRefCached.ImsFwkLoaderClass, method,arr,width,height);

I have also tried using object of class that code is
jclass cls = env->GetObjectClass(obj); jmethodID method = env->GetMethodID(cls, "DispVideo", "([BII)V"); env->CallVoidMethod(cls, method,arr,width,height);

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浅唱々樱花落 2024-12-14 19:03:24

为了调用实例方法，您需要提供该方法所属类的实例，表示为jobject。但是，在这两个示例中，您都尝试使用类定义的实例（表示为 jclass）来调用实例方法。

请尝试以下操作：

jclass cls = env->GetObjectClass(obj);
jmethodID method = env->GetMethodID(cls, "DispVideo", "([BII)V");
env->CallVoidMethod(obj, method, arr, width, height);

请注意第三行代码中的细微差别，其中我使用 obj 作为第一个参数，而不是 cls。

您还可以在实例方法 JNI 函数的文档页面上看到这种差异： http://download.oracle.com/javase/1.5.0/docs/guide/jni/spec/functions.html#wp16656

看看GetMethodID 和 CallMethod - 一个采用 jclass，另一个采用 jobject。

In order to call an instance method, you need to provide an instance of the class the method belng to, represented as an jobject. However, in both examples you are trying to call the instance method with an instance of the class definition, represented as a jclass.

Try the following:

jclass cls = env->GetObjectClass(obj);
jmethodID method = env->GetMethodID(cls, "DispVideo", "([BII)V");
env->CallVoidMethod(obj, method, arr, width, height);

Note the subtle difference in the third line of code, where I use obj as the first parameter, instead of cls.

You can see this difference also on the documentation page for the instance method JNI functions: http://download.oracle.com/javase/1.5.0/docs/guide/jni/spec/functions.html#wp16656

Look at both GetMethodID and Call<type>Method - one takes jclass, the other takes jobject.

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