Android之JNI：Android Studio使用Gradle編譯C/C++源碼

使用Gradle編譯C/C++源碼步驟 

申明NDK工具類，內部定義native方法

package com.coca.firstdemo;

/**
 * Created by Administrator on 2016/6/6.
 */
public class JniShareUtils {
    public native String getLogCount(String params);
}

定位至項目的app文件夾，調用javah命令生成.h文件：

   
   
   
   

    
    
    
    

   
   
   
   
javah com.coca.firstdemo.JniShareUtils

執行完會在.java文件同目錄下生成com_coca_firstdemo_JniShareUtils.h文件，內容以下：

/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class com_coca_firstdemo_JniShareUtils */

#ifndef _Included_com_coca_firstdemo_JniShareUtils
#define _Included_com_coca_firstdemo_JniShareUtils
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     com_coca_firstdemo_JniShareUtils
 * Method:    getLogCount
 * Signature: (Ljava/lang/String;)Ljava/lang/String;
 */
JNIEXPORT jstring JNICALL Java_com_coca_firstdemo_JniShareUtils_getLogCount
  (JNIEnv *, jobject, jstring);

#ifdef __cplusplus
}
#endif
#endif

在app文件夾下新建jni目錄存放生成的.h文件。新建.c文件，名字隨意，內容以下：

#include "com_coca_firstdemo_JniShareUtils.h"

JNIEXPORT jstring JNICALL Java_com_coca_firstdemo_JniShareUtils_getLogCount
        (JNIEnv *env, jobject obj, jstring jstr){
    return (*env)->NewStringUTF(env,"This just a test for Android Studio NDK JNI developer!");
}

在app的build.gradle中添加設置(ABI支持的7種平臺： armeabi, armeabi-v7a, x86, x86_64, mips, mips64, arm64-v8a

defaultConfig {
    //...
    ndk{
        moduleName "wangjun_so_jni"          //生成的so名字,名字隨意
        abiFilters "armeabi", "armeabi-v7a", "x86" //輸出指定三種abi體系結構下的so庫。目前無關緊要。
    }
}

在JniShareUtils中添加靜態初始化代碼：

static {
    System.loadLibrary("wangjun_so_jni");//與上述build.gradle中定義的moduleName對應
}

爲何不用創建Android.mk文件？

在app的build.gradle中按住ctrl點擊ndk代碼塊的modelName便可跳轉至NdkOptions.java文件

package com.android.build.gradle.internal.dsl;
/**
 * DSL object for NDK-related settings.
 */
public class NdkOptions implements CoreNdkOptions, Serializable {
    private static final long serialVersionUID = 1L;

    private String moduleName;
    private String cFlags;
    private List<String> ldLibs;
    private Set<String> abiFilters;
    private String stl;
    private Integer jobs;
}

即ndk代碼塊中可設置的參數有5個，代替了Android.mk中的參數設置。

小Tips：

1.提示錯誤：Error: NDK integration is deprecated in the current plugin. Consider trying the new experimental plugin. For details, see http://tools.android.com/tech-docs/new-build-system/gradle-experimental. Set "android.useDeprecatedNdk=true" in gradle.properties to continue using the current NDK integration.

解決：在gradle.properties中添加android.useDeprecatedNdk=true

來自爲知筆記(Wiz)