andLinux下利用NDK把C代码生成so文件和java交互, 基本无需设置, 亲测OK

1. 下载NDK, 本次版本为 r9d
wget
tar jxvf android-ndk-r9d-linux-x86.tar.bz2
cd android-ndk-r9d
mkdir jni
#将下面2个文件(qiushui_jni.c, Android.mk) 用Winscp拷贝到jni目录下即可. 编译命令如下
./ndk-build
#编译时会看到最后一行为如下:
[armeabi] Install        : libqiushui_jni.so => libs/armeabi/libqiushui_jni.so
#然后在./libs/armeabi下就能看到刚刚生成的.so文件, 将此文件用WINSCP拷贝到安卓工程的同样目录下即可.

2. NDK下的C编程和android.mk

//文件名: qiushui_jni.c

#include <jni.h>
#include <android/log.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define DBG (1) //1=Log cat输出, 0=false
#define JNI_LOG "qiushui"

//-------------------------------------------------------------------------------------------------
//接收java中的数组, 运算后返回int类型
JNIEXPORT jint JNICALL Java_qiushui_Jni_getInt(JNIEnv *env, jobject obj, jintArray arr, jint len)
{
  jint buf[len];
  jint i, sum = 0;

  (*env)->GetIntArrayRegion(env, arr, 0, len, buf);
  for (i = 0; i < len; i++) {
    sum += buf[i];
  }

  return sum;
}

//接收java中的String, 修改后返回String
JNIEXPORT jstring JNICALL Java_qiushui_Jni_getString(JNIEnv *env, jobject obj, jstring str)
{
  char outbuf[128];
  int len = (*env)->GetStringLength(env, str);

  (*env)->GetStringUTFRegion(env, str, 0, len, outbuf);
  if (DBG) __android_log_print(ANDROID_LOG_INFO, JNI_LOG, "Java->JNI: %s", outbuf);
  strcat(outbuf, "---qiushui_007");

  return (*env)->NewStringUTF(env, outbuf);
}

#文件名: Android.mk
LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)

LOCAL_C_INCLUDES := $(LOCAL_PATH)/include
LOCAL_LDLIBS += -L$(SYSROOT)/usr/lib -llog

LOCAL_MODULE := qiushui_jni
LOCAL_SRC_FILES := qiushui_Jni.c

include $(BUILD_SHARED_LIBRARY)

 3. android下java编程
3.1 首先写个调用so的类

package qiushui;

public class Jni {
    static {
      System.loadLibrary("qiushui_jni");
    }

     public native int getInt(int[] arr, int len);
    public native String getString(String str);
}

3.2 然后主进程中就可以自由调用了

package huang.feng;

import qiushui.Jni;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;

public class HelloNDKActivity extends Activity {
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
//        setContentView(R.layout.main);
        TextView textView = new TextView(this);

        Jni jni = new Jni();
        String str_test = "JNI str test: ";
        int[] arr_int = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10};
        int len = arr_int.length;
        textView.setText(jni.getString(str_test) + ", int = " + jni.getInt(arr_int, len));

        setContentView(textView);
    }
}