为使用Android NDK提供帮助

Question

我想在我的项目中使用android NDK。所以我的问题是，如何整合并执行Android NDK的hello-jni的默认示例项目？请给我提供一步一步的解决方案...我对此一无所知......

Answer 1

这是NDK初学者的一个很好的教程：Getting Started with the NDK。

Answer 2

1. First Create Android Project 
2. Then Create Folder in the Project with name jni (Dont use other name) 

3.  Create File With the Android.mk (Rightclick on the jni folder ->New -> File -                     >Android.mk) 
// Coding To Build Path and Access 
LOCAL_PATH :=$(call my-dir)   // This is Common 
include $(CLEAR_VARS)    // This is common`enter code here` 
LOCAL_MODULE := myCFile // myCFile is ur own Name of the module 
       that will be called in Activity) 
LOCAL_SRC_FILES := my.c // Our C File What should be given in C 
                      file creation 

include $(BUILD_SHARED_LIBRARY) 


4. Create C File like above With ur own name with the extension .c (This file will be 
                  used in LOCAL_SRC_FILES) 
        C File Will Look Like this: 
Note : 
// Your Package name com.JniMyDemo Then Your Activity File and then the Function name for c file 
So that I used jint(return value) 
(Java) its must 
(com_JniDemo) is Specified in Package name(com.JniDemo) we couldnt use . for package so 
we put underscore for c file) 
(JniMyDemoActivity) Is my class 

First two arguement is Important one others are our own variable for function // 

Include two header file string.h,jni.h 


#include "string.h" 
#include "jni.h" 

jint Java_com_JniMyDemo_JniMyDemoActivity_add(JNIEnv *env,jobject jobj,jint n1,jint n2) 
{ 
jint a,b,c; 
a=n1; 
b=n2; 
return (a+b); 
} 

5. Then Call the The C File Like this 

// Activity Look like this 

public class JniMyDemoActivity extends Activity { 
    /** Called when the activity is first created. */ 
    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     TextView txt =new TextView(this); 
     txt.setText(" "+add(100,100)); 
     setContentView(txt); 
    } 

    private native int add(int i,int j,int k); 
    static 
    { 
     System.loadLibrary("myCFile"); 
    } 
} 

6.  Then Compile the C File by 
    Starting Terminal (cmd prompt) Type the Project Path like (cd Project Path) and Enter 
    Then type the   (Ndk Location/ndk-build) it will automatically compile & ur jni    folder 
7. If it success means Start the Actvity it will show the Result of Addition 

Answer 3

了解它是记住事情的艰难方法。您从developers.android.com下载的Andaroid NDK内部，您将拥有docs文件夹，您将在其中拥有不同的文档，这些文档将清楚地告诉您应该如何以及何时使用NDK。尤其是完全通过 OVERVIEW.HTML。 http://developer.android.com/sdk/ndk/index.html

我这样做，当我第一次使用NDK。我强烈建议只有这样..

如果你感到困惑什么是本地代码 - >它是你想用于Android应用程序的C或C++或汇编代码。这被称为本地代码，因为它不是用java语言编写的。

所有最优秀的。

Answer 4

你在这里有一个很好的教程，解释你需要使用NDK，如何创建一个函数以及如何使用它们，这很容易遵循。 http://marakana.com/s/introduction_to_ndk,1153/index.html，对不起我的英文，而不是我的母语。