Android NDK JNI이용하여 C/C++ 라이브러리 호출하기

NDK JNI이용하여 C/C++ 라이브러리 호출하기

- gradle 설정 : http://ghj1001020.tistory.com/761  참고

- calculator 라는 C파일(라이브러리)을 만들어서 JNI를 통한 호출

MainActivity.java : Jni 로드및 호출

package com.ghj.jnitwo;
 
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.widget.TextView;
 
public class MainActivity extends AppCompatActivity {
 
    TextView txtResult;
 
 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        int add = getCalculator(12, 3, '+');
        int minus = getCalculator(12, 3, '-');
        int multiply = getCalculator(12, 3, '*');
        int divide = getCalculator(12, 3, '/');
 
        txtResult.append("덧셈 : "+add+"\n");
        txtResult.append("뺄셈 : "+minus+"\n");
        txtResult.append("곱셈 : "+multiply+"\n");
        txtResult.append("나눗셈 : "+divide+"\n");
    }
 
 
    static {
        //JNI 로드
        System.loadLibrary("jni-calculator");
    }
 
    public native int getCalculator(int a, int b, char type);
}
 

jni-calculator.c : Jni 파일

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#include <jni.h> #include "calculator.h"     /**  * @desc : JNI 를 이용하여 c/c++ 로 된 라이브러리를 호출할 수 있다  */ JNIEXPORT jint JNICALL Java_com_ghj_jnitwo_MainActivity_getCalculator(JNIEnv *env, jobject instance, jint a, jint b, jchar type) {       if(type == '+'){         add(a, b);     }else if(type == '-'){         minus(a, b);     }else if(type == '*'){         multiply(a, b);     }else if(type == '/'){         divide(a, b);     } } Colored by Color Scripter

cs

calculator.h : 임의의 라이브러리 헤더파일

#ifndef JNITWO_CALCULATOR_H
#define JNITWO_CALCULATOR_H
 
extern int add(int a, int b);
extern int minus(int a, int b);
extern int multiply(int a, int b);
extern int divide(int a, int b);
 
#endif //JNITWO_CALCULATOR_H
 

calculator.c : 임의의 라이브러리 소스파일

#include "calculator.h"
 
//덧셈
int add(int a, int b){
    return a + b;
}
 
//뺄셈
int minus(int a, int b){
    return a - b;
}
 
//곱셈
int multiply(int a, int b){
    return a * b;
}
 
//나눗셈
int divide(int a, int b){
    return a / b;
}

main_activity.xml : 화면

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.ghj.jnitwo.MainActivity">
 
    <TextView
        android:id="@+id/txtResult"
        android:layout_width="match_parent"
        android:layout_height="wrap_content" />
</LinearLayout>
 

build.gradle

//apply plugin: 'com.android.application'
apply plugin: 'com.android.model.application'
 
model {
    android {
        compileSdkVersion 25
        buildToolsVersion "25.0.3"
        defaultConfig {
            applicationId "com.ghj.jnitwo"
            minSdkVersion.apiLevel 19
            targetSdkVersion.apiLevel 25
            versionCode 1
            versionName "1.0"
            testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
        }
        buildTypes {
            release {
                minifyEnabled false
//                proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
                proguardFiles.add(file('proguard-android.txt'))
            }
        }
 
        ndk {
            moduleName 'jni-calculator'
 
        }
    }
}
...

결과

c라이브러리를 이용하여 사칙연산을 실행