JNI动态库生成、编译、查看相关简易资料

有一篇好博文，大家可以看下http://www.cnblogs.com/zhangweia/archive/2010/09/16/1828176.html，我这里是参考其做的另外一个
javah -classpath ../../NVPACK/android-sdk-linux/platforms/android-19/android.jar:./bin/classes -d jni com.android.imagesrppl.MainActivity
进入工程目录，直接编译头文件的形式,最后com.android.imagesrppl.MainActivity是src文件对应要编译的native函数所在的类文件
../../NVPACK/android-sdk-linux/platforms/android-19/android.jar sdk的路径，根据自己的路径来设置

生成的头文件名字为：com_android_imagesrppl_MainActivity.h com_android_imagesrppl包名字 MainActivity native函数所在的类名字
对应的头文件举例：
/* DO NOT EDIT THIS FILE - it is machine generated */
#include <jni.h>
/* Header for class _Included_com_android_imagesrppl_MainActivity */

#ifndef _Included_com_android_imagesrppl_MainActivity
#define _Included_com_android_imagesrppl_MainActivity
#ifdef __cplusplus
extern "C" {
#endif
/*
* Class: com_android_imagesr_MainActivity
* Method: dehaze
* Signature: (II[B[B)V
*/
JNIEXPORT void JNICALL Java_com_android_imagesrppl_MainActivity_cMethod
(JNIEnv *, jobject, jint, jint, jfloat, jint, jint, jbyteArray, jbyteArray, jint);

#ifdef __cplusplus
}
#endif
#endif
对应的C文件举例：
#include <jni.h>
#include <stdio.h>
#include <stdlib.h>
#include "com_android_imagesrppl_MainActivity.h"
#include "./include/ppl/ppl.h"
#include "./include/ppl/image/image.h"

#include <android/log.h>
#define LOG_TAG "JNI"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, LOG_TAG, __VA_ARGS__)

#define uchar unsigned char

void SR_C(int h, int w, float factor, int out_h, int out_w, signed char *data, signed char *dehazeData, int mode) {
　　method()；//so中要调用的方法
}
JNIEXPORT void JNICALL Java_com_android_imagesrppl_MainActivity_cMethod
(JNIEnv *env, jobject obj, jint h, jint w, jfloat factor, jint out_h, jint out_w, jbyteArray data, jbyteArray dehazeData, jint mode) {
　　LOGI("JNI");
　　jbyte *cData = env->GetByteArrayElements(data, NULL);
　　jbyte *cDehazeData = env->GetByteArrayElements(dehazeData, NULL);

　　SR_C(h, w, factor, out_h, out_w, cData, cDehazeData, mode);

　　env->ReleaseByteArrayElements(data, cData, NULL);
　　env->ReleaseByteArrayElements(dehazeData, cDehazeData, NULL);
}
一般在jin目录下建立include和lib，分别存放头文件和库文件；然后在makefile文件中指定对应的目录即可
Android.mk文件举例
LOCAL_PATH := $(call my-dir)
#LOCAL_CFLAGS := -O3 -mfpu=neon -mfloat-abi=hard -mcpu=cortex-a15 -ftree-vectorize -flax-vector-conversions

#arm neon 常用选项

#LOCAL_CXXFLAGS :=-O3 -mfpu=neon -march=armv7 -mfloat-abi=softfp -fPIC -ftree-vectorize -flax-vector-conversions
#LOCAL_CFLAGS :=-O3 -mfpu=neon -march=armv7 -mfloat-abi=softfp -fPIC -ftree-vectorize -flax-vector-conversions

include $(CLEAR_VARS)
LOCAL_MODULE := libppl_common
LOCAL_SRC_FILES := ./lib/libppl_common.so
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libppl_image
LOCAL_SRC_FILES := ./lib/libppl_image.so
include $(PREBUILT_SHARED_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := libcudart_static
LOCAL_LIB_PATH += $(CUDA_TOOLKIT_ROOT)/targets/armv7-linux-androideabi/lib/
LOCAL_SRC_FILES := $(LOCAL_LIB_PATH)/libcudart_static.a
include $(PREBUILT_STATIC_LIBRARY)

include $(CLEAR_VARS)
LOCAL_MODULE := imagesr

MY_PREFIX := $(LOCAL_PATH)/
MY_SOURCES := $(wildcard $(LOCAL_PATH)/*.cpp)
LOCAL_SRC_FILES := $(MY_SOURCES:$(MY_PREFIX)%=%)

LOCAL_CFLAGS +=-DPPL_USE_ARM
LOCAL_STATIC_LIBRARIES := libcudart_static
LOCAL_SHARED_LIBRARIES := libppl_common libppl_image
LOCAL_STATIC_LIBRARIES += nv_and_util nv_egl_util nv_glesutil nv_shader nv_file
LOCAL_LDLIBS := -landroid -lGLESv2 -lEGL -llog

LOCAL_C_INCLUDES += $(LOCAL_PATH)/include

LOCAL_C_INCLUDES += $(CUDA_TOOLKIT_ROOT)/targets/armv7-linux-androideabi/include

include $(BUILD_SHARED_LIBRARY)

Application.mk文件举例
APP_ABI := armeabi-v7a
APP_PLATFORM := android-19
APP_STL := gnustl_static

调用的时候在类中load一下就可以了,举例：
native void cMethod(int h, int w, float factor, int out_h, int out_w, byte[] data, byte[] dehazeData, int mode);
static {
　　System.loadLibrary("imagesr");
}

a. 查看so是不是编译成ARM模式下的so
　　$ file libtest.so
　　libtest.so: ELF 32-bit LSB shared object, ARM, EABI5 version 1 (SYSV), dynamically linked, not stripped

b. 如果别人提供了你一个so，查看提供了哪些方法，更详细的用法，查看nm命令
　　$ nm libtutorial.so |grep T
　　00001344 a _GLOBAL_OFFSET_TABLE_
　　000002a8 T getinformation
　　000002b4 T getinformation2

生成so文件的makefile文件举例：
主要是指定编译器为NDK的编译器即可，其他的和一般的so文件的编译一样，不懂的可以看下“跟我一起写Makefile-陈皓”
一下是我的makefile，大家千万不要照葫芦画瓢！仅当自己mark一下用
#environment setup
GCC=$(NDK_ROOT)/toolchains/arm-linux-androideabi-4.6/gen_standalone/linux-x86_64/bin/arm-linux-androideabi-g++
NVCC=$(CUDA_TOOLKIT_ROOT)/bin/nvcc -ccbin $(GCC) -target-cpu-arch=ARM -m32 -arch=sm_32 -O3 -Xptxas '-dlcm=ca' -target-os-variant=Android

#INCLUDES+= /helper/files/include

CFLAGS += $(addprefix -I, $(INCLUDES))
ARM_CFLAGS += -O3 -mfpu=neon -mfloat-abi=softfp -mcpu=cortex-a15 -ftree-vectorize -flax-vector-conversions -I/home/ubuntu/NVPACK/android-ndk-r10c/toolchains/arm-linux-androideabi-4.6/gen_standalone/linux-x86_64/lib/gcc/arm-linux-androideabi/4.6/include

OBJS += \
sr_ARM.o sr_CUDA.o

%.o: %.cu
　　$(NVCC) $(CFLAGS) $(EXTRA_CFLAGS) -c -o "$@" "$<"

%.o: %.cpp
　　$(GCC) $(CFLAGS) $(ARM_CFLAGS) -c -o "$@" "$<"

libsr_C.a: $(OBJS)
　　　　$(NVCC) -lib -o "$@" $(OBJS)

libsr_C.so: $(OBJS)
　　$(NVCC) -shared -o "$@" $(OBJS)

clean:
　　rm -rf *.a $(OBJS)