Android Studio 如何編譯SO

1，編寫native java文件

public class OpenCvRebuild {


    static {
        System.loadLibrary("openCvRebuild");
    }
    public static native void  testOpenCV(String name,int num);
    public static native String testReturnString(float num);
    public static native int testReturnInt(double num);
    public static native float testReturnFloat(String name,int num,float order,double age);
    public static native double testReturnDouble(String test);
}

2.生成對應的.h文件，使用最基礎的方法

2.1首先將java文件編譯成.class文件 ，使用命令javac OpenCvRebuild.java

打開Android Studio的Terminal工具，定位到OpenCvRebuild.java所在的目錄（可以直接將OpenCvRebuild.java所在目錄直接拖拽到Termianl中）：

D:\demo\MyApplication\app\src\main\java\com\test\myapplication>javac OpenCvRebuild.java

D:\demo\MyApplication\app\src\main\java\com\test\myapplication>

刷新一下目錄，就可以看到在myapplication目錄下面多了一個.class文件：

2.2 將.class文件生成.h文件

在Terminal工具中將文件路徑定位到java

輸入指令：

D:\demo\MyApplication\app\src\main\java>javah com.test.myapplication.OpenCvRebuild

D:\demo\MyApplication\app\src\main\java>

之後刷新目錄可以得到一個.h文件

到此位置，.h文件就創建好了

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

#ifndef _Included_com_test_myapplication_OpenCvRebuild
#define _Included_com_test_myapplication_OpenCvRebuild
#ifdef __cplusplus
extern "C" {
#endif
/*
 * Class:     com_test_myapplication_OpenCvRebuild
 * Method:    testOpenCV
 * Signature: (Ljava/lang/String;I)V
 */
JNIEXPORT void JNICALL Java_com_test_myapplication_OpenCvRebuild_testOpenCV
  (JNIEnv *, jobject, jstring, jint);

/*
 * Class:     com_test_myapplication_OpenCvRebuild
 * Method:    testReturnString
 * Signature: (F)Ljava/lang/String;
 */
JNIEXPORT jstring JNICALL Java_com_test_myapplication_OpenCvRebuild_testReturnString
  (JNIEnv *, jobject, jfloat);

/*
 * Class:     com_test_myapplication_OpenCvRebuild
 * Method:    testReturnInt
 * Signature: (D)I
 */
JNIEXPORT jint JNICALL Java_com_test_myapplication_OpenCvRebuild_testReturnInt
  (JNIEnv *, jobject, jdouble);

/*
 * Class:     com_test_myapplication_OpenCvRebuild
 * Method:    testReturnFloat
 * Signature: (Ljava/lang/String;IFD)F
 */
JNIEXPORT jfloat JNICALL Java_com_test_myapplication_OpenCvRebuild_testReturnFloat
  (JNIEnv *, jobject, jstring, jint, jfloat, jdouble);

/*
 * Class:     com_test_myapplication_OpenCvRebuild
 * Method:    testReturnDouble
 * Signature: (Ljava/lang/String;)D
 */
JNIEXPORT jdouble JNICALL Java_com_test_myapplication_OpenCvRebuild_testReturnDouble
  (JNIEnv *, jobject, jstring);

#ifdef __cplusplus
}
#endif
#endif

下面根據.h文件寫.c或.cpp文件

3.在main目錄下創建一個jni目錄，將.h文件剪切到jni目錄下面，並根據.h文件生成.c文件

 

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

/*
 * Class:     com_test_myapplication_OpenCvRebuild
 * Method:    testOpenCV
 * Signature: (Ljava/lang/String;I)V
 */
JNIEXPORT void JNICALL Java_com_test_myapplication_OpenCvRebuild_testOpenCV
   (JNIEnv *env, jobject object, jstring name, jint num){


  }

/*
 * Class:     com_test_myapplication_OpenCvRebuild
 * Method:    testReturnString
 * Signature: (F)Ljava/lang/String;
 */
JNIEXPORT jstring JNICALL Java_com_test_myapplication_OpenCvRebuild_testReturnString
  (JNIEnv *env, jobject obj, jfloat  num){

    return (*env)->NewStringUTF(env,"testReturnString");
  }

/*
 * Class:     com_test_myapplication_OpenCvRebuild
 * Method:    testReturnInt
 * Signature: (D)I
 */
JNIEXPORT jint JNICALL Java_com_test_myapplication_OpenCvRebuild_testReturnInt
  (JNIEnv *env, jobject obj, jdouble num){
 return 10;
  }

/*
 * Class:     com_test_myapplication_OpenCvRebuild
 * Method:    testReturnFloat
 * Signature: (Ljava/lang/String;IFD)F
 */
JNIEXPORT jfloat JNICALL Java_com_test_myapplication_OpenCvRebuild_testReturnFloat
  (JNIEnv *env, jobject obj, jstring name, jint intNum, jfloat floatNum, jdouble doubleNum){

return 1.10;
  }

JNIEXPORT jdouble JNICALL Java_com_test_myapplication_OpenCvRebuild_testReturnDouble
  (JNIEnv *env, jobject obj, jstring name){

return 2.0004;
  }

 

4.再在jni目錄下面創建Android.mk和Application.mk

Android.mk   

LOCAL_MODULE標識生成的so庫名稱

LOCAL_SRC_FILES：jni目錄下的.c文件，如果是多個.c文件可以用"\"分開

LOCAL_PATH := $(call my-dir)

include $(CLEAR_VARS)


LOCAL_MODULE    := openCvRebuild   

LOCAL_SRC_FILES :=\
testC.c

include $(BUILD_SHARED_LIBRARY)

 

Application.mk

APP_ABI := armeabi-v7a  arm64-v8a  x86  x86_64
APP_MODULES := openCvRebuild
APP_CFLAGS += -DSTDC_HEADERS
APP_PLATFORM := android-21

5.現在所有的準備文件都已經做好，可以直接打包.so

在Terminal工具中定位到jni目錄，輸入指令ndk-build

刷新目錄，得到一個libs包，將這個包中的內容粘貼到jniLibs中，就可以調用了