代码链接：
https://github.com/watersink/MobileNetSSD-linux-as
本代码可以在模拟器下进行跑。
环境：
Android studio 3.6
Sdk：android10 api 29
Ndk：r15c
Ncnn：20200226
Linux下的代码测试：
mkdir build
cd build
cmake ..
make
./ssd效果：
Android下的开发：
(1)增加ncnn的依赖库.a（src/main/jniLibs）
增加ncnn的头文件include（src/main/cpp）
(2)增加ssd模型文件（src/main/assets）
和ssd模型的加密后的*.id.h文件（src/main/cpp）
(3)增加需要使用的图片（src/main/res/drawable）
(4)修改布局文件（src/main/res/layout/activity_main.xml）
(5)修改java部分代码（src/main/java）
增加MobileNetssd，主要实现初始化Init和检测Detect代码
package com.example.mobilenetssd;
import android.graphics.Bitmap;
public class MobileNetssd {
public native boolean Init(byte[] param, byte[] bin); // 初始化函数
public native float[] Detect(Bitmap bitmap); // 检测函数
// Used to load the 'native-lib' library on application startup.
static {
System.loadLibrary("MobileNetssd");
}
}
//修改MainActivity代码，主要onCreate函数中实现模型初始化，label文件读取，模型的检测，结果显示。
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
try
{
initMobileNetSSD();//初始化模型
Log.e("MainActivity", "initMobileNetSSD ok");
} catch (IOException e) {
Log.e("MainActivity", "initMobileNetSSD error");
}
readCacheLabelFromLocalFile();//初始化读取words.txt
init_view();//检测+view画图
}
(6)修改cpp部分代码（src/main/cpp）
MobileNetssd.h和MobileNetssd.cpp分别实现了MOBILENETSSD及其相关方法。
ssd_jni.cpp实现了jnl方式的c++方法。
MobileNetssd.h中的MOBILENETSSD类及其方法，
class MOBILENETSSD {
public:
MOBILENETSSD(string param_path, string bin_path);
MOBILENETSSD(ncnn::Mat param_path, ncnn::Mat bin_path);
ncnn::Mat detect(ncnn::Mat in);
~MOBILENETSSD();
private:
ncnn::Net net;
const int target_size = 300;
const float mean_vals[3] = {127.5f, 127.5f, 127.5f};
const float norm_vals[3] = {0.007843f, 0.007843f, 0.007843f};
};
MobileNetssd.cpp中的具体实现，
MOBILENETSSD::MOBILENETSSD(string param_path, string bin_path) {
const char *param_path_char = param_path.c_str();
const char *bin_path_char = bin_path.c_str();
int ret_param = net.load_param_bin(param_path_char);
int ret_bin = net.load_model(bin_path_char);
//std::cout<<"### "<<ret_param<<" "<<ret_bin<<std::endl;
}
MOBILENETSSD::MOBILENETSSD(ncnn::Mat param_path, ncnn::Mat bin_path) {
int ret_param = net.load_param((const unsigned char *)param_path);
int ret_bin = net.load_model((const unsigned char *)bin_path);
LOGD("############### %d %d", ret_param,ret_bin);
//std::cout<<"### "<<ret_param<<" "<<ret_bin<<std::endl;
}
ncnn::Mat MOBILENETSSD::detect(ncnn::Mat in) {
int img_w = in.w;
int img_h = in.h;
//ncnn::Mat in = ncnn::Mat::from_pixels_resize(bgr.data, ncnn::Mat::PIXEL_BGR, bgr.cols, bgr.rows, target_size, target_size);
in.substract_mean_normalize(mean_vals, norm_vals);
ncnn::Extractor ex = net.create_extractor();
ex.set_num_threads(2);
ex.input(mobilenet_ssd_voc_ncnn_param_id::BLOB_data, in);
ncnn::Mat out;
ex.extract(mobilenet_ssd_voc_ncnn_param_id::BLOB_detection_out, out);
return out;
}
MOBILENETSSD::~MOBILENETSSD() {
net.clear();
}
ssd_jni.cpp的具体实现，
static MOBILENETSSD *ncnn_net;
extern "C"
JNIEXPORT jboolean JNICALL
Java_com_example_mobilenetssd_MobileNetssd_Init(JNIEnv *env, jobject thiz, jbyteArray param,
jbyteArray bin) {
// TODO: implement Init()
ncnn::Mat ncnn_param;
ncnn::Mat ncnn_bin;
// init param
{
int len = env->GetArrayLength(param);
ncnn_param.create(len, (size_t) 1u);
env->GetByteArrayRegion(param, 0, len, (jbyte *) ncnn_param);
}
// init bin
{
int len = env->GetArrayLength(bin);
ncnn_bin.create(len, (size_t) 1u);
env->GetByteArrayRegion(bin, 0, len, (jbyte *) ncnn_bin);
}
ncnn_net = new MOBILENETSSD(ncnn_param,ncnn_bin);
return JNI_TRUE;
}
extern "C"
JNIEXPORT jfloatArray JNICALL
Java_com_example_mobilenetssd_MobileNetssd_Detect(JNIEnv *env, jobject thiz, jobject bitmap) {
// TODO: implement Detect()
// ncnn from bitmap
ncnn::Mat in;
{
AndroidBitmapInfo info;
AndroidBitmap_getInfo(env, bitmap, &info);
int width = info.width;
int height = info.height;
if (info.format != ANDROID_BITMAP_FORMAT_RGBA_8888)
return NULL;
void* indata;
AndroidBitmap_lockPixels(env, bitmap, &indata);
// 把像素转换成data，并指定通道顺序
// 因为图像预处理每个网络层输入的数据格式不一样一般为300*300 128*128等等所以这类需要一个resize的操作可以在cpp中写，也可以是java读入图片时有个resize操作
//in = ncnn::Mat::from_pixels_resize((const unsigned char*)indata, ncnn::Mat::PIXEL_RGBA2RGB, width, height,300,300);
in = ncnn::Mat::from_pixels(static_cast(indata), ncnn::Mat::PIXEL_RGBA2RGB, width, height);
// 下面一行为debug代码
__android_log_print(ANDROID_LOG_DEBUG, "MobilenetssdJniIn", "Mobilenetssd_predict_has_input1, in.w: %d; in.h: %d", in.w, in.h);
//AndroidBitmap_unlockPixels(env, bitmap);
}
{
ncnn::Mat out = ncnn_net->detect(in);
int output_wsize = out.w;
int output_hsize = out.h;
//输出整理
jfloat *output[output_wsize * output_hsize]; // float类型
for(int i = 0; i< out.h; i++) {
for (int j = 0; j NewFloatArray(output_wsize * output_hsize);
if (jOutputData == nullptr) return nullptr;
env->SetFloatArrayRegion(jOutputData, 0, output_wsize * output_hsize,
reinterpret_cast(*output));
return jOutputData;
}
}
(7)CMakeLists修改（src/main/cpp/CMakeLists），加入ncnn路径
cmake_minimum_required(VERSION 3.4.1)
#include头文件目录
include_directories(include)
#添加ncnn库
#source directory源文件目录
file(GLOB SSD_SRC *.h
*.cpp)
set(SSD_COMPILE_CODE ${SSD_SRC})
add_library(libncnn STATIC IMPORTED )
set_target_properties(libncnn
PROPERTIES IMPORTED_LOCATION
${CMAKE_SOURCE_DIR}/../jniLibs/${ANDROID_ABI}/libncnn.a)
add_library( # Sets the name of the library.
MobileNetssd ## 为生成.so的文字最好直接和.c名字一样,需要更改
# Sets the library as a shared library.
SHARED
# Provides a relative path to your source file(s).
${SSD_COMPILE_CODE})##cpp文件的name
find_library( # Sets the name of the path variable.
log-lib
log )
target_link_libraries( # Specifies the target library.
MobileNetssd
libncnn
android
jnigraphics
# Links the target library to the log library
# included in the NDK.
${log-lib} )
(8) build.gradle修改，增加ndk,cmake选项。
externalNativeBuild {
cmake {
arguments "-DANDROID_TOOLCHAIN=clang"
cFlags "-fopenmp -O2 -fvisibility=hidden -fomit-frame-pointer -fstrict-aliasing -ffunction-sections -fdata-sections -ffast-math "
cppFlags "-fopenmp -O2 -fvisibility=hidden -fvisibility-inlines-hidden -fomit-frame-pointer -fstrict-aliasing -ffunction-sections -fdata-sections -ffast-math "
arguments "-DANDROID_STL=c++_shared", "-DANDROID_CPP_FEATURES=rtti exceptions"
cppFlags ""
cppFlags "-std=c++11"
cppFlags "-frtti"
cppFlags "-fexceptions"
}
}
ndk {
abiFilters 'armeabi-v7a'// , 'arm64-v8a' //,'x86', 'x86_64', 'armeabi'
stl "gnustl_static"
}
(9)整体目录结构，
运行结果：
作者：watersink
