什么是写的Andr​​oid NDK本地方法签名的正确方法是什么？ [英] What is the correct way to write native method signatures in Android NDK?

问题描述

我有NDK库和相应的Java类的工作实现。但我不能够重载方法添加到类。目前我的类包含：

I have a working implementation of NDK library and corresponding Java-class. But I am not able to add overloaded method to that class. Currently my class contains:

package com.package;

public class MyClass
{
  public static native String getFileName();
  static
  {
    System.loadLibrary("mylib");
  }
}

我jniwrappers.cpp文件具有以下声明：

My jniwrappers.cpp file has the following declaration:

JNIEXPORT jstring JNICALL
Java_com_package_MyClass_getFileName(_JNIEnv* env, jobject thiz);

到现在为止一切正常。但接下来我修改我的类：

Up to this point everything is working fine. But next I modify my class:

package com.package;

public class MyClass
{
  public static native String getFileName();
  public static native String getFileName(int index);
  ...
}

和添加到jniwrappers.cpp另一声明：

And add to jniwrappers.cpp another declaration:

JNIEXPORT jstring JNICALL
Java_com_package_MyClass_getFileName__I(_JNIEnv* env, jobject thiz, jint index);

它编译罚款，Android应用程序启动时，没有得到的UnsatisfiedLinkError但是当它调用第二个方法与参数的第一个C ++函数被调用，但没有第二个。我有其他的方法，在该类论点，但他们都不超载所以它们各自的JNI签名不包含的参数。

It compiles fine, Android application starts, does not get UnsatisfiedLinkError but when it calls the second method with the argument the first C++ function is being called but not the second. I have other methods with arguments in that class but none of them are overloaded so their respective JNI signatures do not contain arguments.

那么，我究竟做错了什么？

So, what am I doing wrong?

推荐答案

您必须添加一个 __ 到原来的getFileName函数的结束，现在它是超载。您2 C函数原型现在应该是这样的：

You have to add a __ onto the end of the original getFileName function now that it is overloaded. Your 2 C function prototypes should now look like this:

JNIEXPORT jstring JNICALL Java_com_package_MyClass_getFileName__
  (JNIEnv *, jclass);

JNIEXPORT jstring JNICALL Java_com_package_MyClass_getFileName__I
  (JNIEnv *, jclass, jint);

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