廢話不多說!

<1> : 新建一個DurianAsJni的android工程.

<2> : 新建一個jni的java介面類:

package org.durian.durianasjni;

/**
 * Project name : DurianAsJni
 * Created by zhibao.liu on 2016/3/28.
 * Time : 19:33
 * Email [email protected]
 * Action : durian
 */
public class aslib {

    public native float getDurianLibVersion();

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

<3> : 然後在src目錄下新建一個jni目錄,在jni目錄下新增Android.mk和Application.mk.

<4> : 由於這裡使用的是onload的方式,所以新建jni_onload.h,jni_onload.cpp

jni_onload.h

#include<jni.h>
#ifndef _ON_LOAD_HEADER_H__
#define _ON_LOAD_HEADER_H__
#ifdef __cplusplus
extern "C" {
#endif

JNIEnv* getJNIEnv();
int jniThrowException(JNIEnv *env,const char* className,const char* msg);
int jniRegisterNativeMethods(JNIEnv* env,const char* className,const JNINativeMethod* gMethod,int numMethods);

#ifdef __cplusplus
}
#endif
#endif
 

jni_onload.cpp

#include "jni_onload.h"
#include "durian_opencv.h"

extern int register_android_jni_durian_android(JNIEnv *env);
/*
extern int register_android_jni_durian_android_1(JNIEnv *env);
...
extern int register_android_jni_durian_android_n(JNIEnv *env);
*/

static JavaVM *sEnv;

int jniThrowException(JNIEnv *env, const char* className, const char* msg) {

    jclass exceptionClass = env->FindClass(className);

    if (exceptionClass == NULL) {
        return -1;
    }

    if (env->ThrowNew(exceptionClass, msg) != JNI_OK) {

    }

    return 0;

}

JNIEnv* getJNIEnv() {

    JNIEnv* env = NULL;

    if (sEnv->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK) {
        return NULL;
    }

    return env;

}

int jniRegisterNativeMethods(JNIEnv* env, const char* className,
        const JNINativeMethod* gMethods, int numMethods) {
    jclass clazz;

    clazz = env->FindClass(className);

    if (clazz == NULL) {
        return -1;
    }

    if (env->RegisterNatives(clazz, gMethods, numMethods) < 0) {
        return -1;
    }

    return 0;

}

jint JNI_OnLoad(JavaVM* vm, void* reserved) {

    JNIEnv* env = NULL;
    jint result = JNI_ERR;
    sEnv = vm;

    if (vm->GetEnv((void**) &env, JNI_VERSION_1_4) != JNI_OK) {
        return result;
    }

    LOGI("JNI_OnLoad...");
    /*ready to register all methods
    */

    if (register_android_jni_durian_android(env) != JNI_OK) {
        goto end;
    }

    //following could do it as the previous the way of register

    /*if (register_android_jni_durian_android_1(env) != JNI_OK) {
            goto end;
        }
    ...
    if (register_android_jni_durian_android_n(env) != JNI_OK) {
            goto end;
        }*/


    return JNI_VERSION_1_4;

    end: return result;

}
 

這兩個檔案都被我弄成標配檔案了.

<5> : 功能原始碼,在jni目錄下新建durian_opencv.h和durian_opencv.cpp,程式碼如下:

durian_opencv.h

//
// Created by $zhibao.liu on 2016/3/28.
//

#ifndef DURIANASJNI_DURIAN_OPENCV_H
#define DURIANASJNI_DURIAN_OPENCV_H
#include<string.h>
#include<stdlib.h>
#include <android/log.h>
#include "jni_onload.h"

#define LOG_TAG "durian"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO,LOG_TAG,__VA_ARGS__)
#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG, LOG_TAG, __VA_ARGS__)
#define LOGW(...) __android_log_print(ANDROID_LOG_WARN,LOG_TAG,__VA_ARGS__)
#define LOGE(...) __android_log_print(ANDROID_LOG_ERROR,LOG_TAG,__VA_ARGS__)
#define LOGF(...) __android_log_print(ANDROID_LOG_FATAL,LOG_TAG,__VA_ARGS__)


#endif //DURIANASJNI_DURIAN_OPENCV_H

對應的durian_opencv.cpp

//
// Created by $zhibao.liu on 2016/3/28.
//
#include "durian_opencv.h"
const static char *classpath="org/durian/durianasjni/aslib";
namespace android{

    float getDurianLibVersion(JNIEnv *env, jobject thiz){
        return 0.5;
    }

}

using namespace android;

static JNINativeMethod mMethods[] = {

        { "getDurianLibVersion", "()F",(void *) getDurianLibVersion },

};

int register_android_jni_durian_android(JNIEnv* env) {

    return jniRegisterNativeMethods(env, classpath, mMethods,sizeof(mMethods) / sizeof(mMethods[0]));

}

寫完c原始碼後,修改Android.mk檔案:

LOCAL_PATH $(call my-dir)
include $(CLEAR_VARS)

LOCAL_MODULE := aslib
LOCAL_SRC_INCLUDE=jni_onload.cpp durian_opencv.cpp
LOCAL_LDLIBS := -llog

include $(BUILD_SHARED_LIBRARY)

<6> : NDK環境配置:

gradle.properties檔案最後一行新增:

android.useDeprecatedNdk=true

local.properties檔案最後一行新增NDK包的路徑:

ndk.dir=D\:\\liuzhibao\\Android\\android-ndk-r10

最後再build.gradle檔案中新增ndk編譯:

ndk{
            moduleName "aslib"
            ldLibs "log", "z", "m"
            abiFilters "armeabi", "armeabi-v7a", "x86"
        }

就差不多了

<7> : 在android java主程式中新增測試程式:

package org.durian.durianasjni;

import android.os.Bundle;
import android.support.design.widget.FloatingActionButton;
import android.support.design.widget.Snackbar;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.view.View;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity {

    private aslib mlib;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mlib=new aslib();
        float ver=mlib.getDurianLibVersion();
        Toast.makeText(MainActivity.this,"lib version : "+ver,Toast.LENGTH_SHORT).show();

    }


}