文件的拆分与合并

1、声明本地方法

	public native void diff(String path,String path_pattern,int count);
	
	public native void patch(String path,int count,String path_pattern);

 

2、生成头文件

JNIEXPORT void JNICALL Java_com_dongnaoedu_jni_JniTest_diff
(JNIEnv *, jclass, jstring, jstring,jint);

JNIEXPORT void JNICALL Java_com_dongnaoedu_jni_JniTest_patch
(JNIEnv *, jclass, jstring, jint, jstring);

3、实现声明的方法

JNIEXPORT void JNICALL Java_com_dongnaoedu_jni_JniTest_diff
(JNIEnv *env, jclass jcls, jstring path_jstr, jstring path_pattern_jstr, jint file_num)
{

	//需要分割的文件路径
	const char *path = (*env)->GetStringUTFChars(env, path_jstr,NULL);
	const char *path_pattern = (*env)->GetStringUTFChars(env, path_pattern_jstr, NULL);
	//得到分割之后的文件的路径列表
	char **patches = malloc(sizeof(char*) *file_num);
	int i = 0;
	for (; i < file_num; i++){
		patches[i] = malloc(sizeof(char)* 100);
		//元素赋值
		//C://jason/ly.png
		//子文件 C://jason/ly_%d.png
		sprintf(patches[i], path_pattern, (i + 1));
		printf("patch path:%s \n",patches[i]);
	}


	//不断读取path文件，循环写入file_num个文件中
	//整除
	//文件大小：90，分成9个文件，每个文件10
	//不整除
	//文件大小：110，分成9个文件
	//前（9-1)个文件为（110/（9-1））=13
	//最后一个文件（110%（9-1））=6

	int filesize = get_file_size(path);
	FILE *fpr = fopen(path, "rb");
	//整除
	if (filesize%file_num == 0){
		//单个文件大小
		int part = filesize / file_num;
		i = 0;
		//逐一写入不同分割子文件中
		for (; i < file_num; i++){
			FILE *fpw = fopen(patches[i], "wb");
			int j = 0;
	
			for (; j < part; j++){
				//边读边写
				fputc(fgetc(fpr), fpw);
			}
			fclose(fpw);
		}
	}
	else
	{
		//单个文件大小
		int part = filesize / (file_num -1);
		i = 0;
		//逐一写入不同分割子文件中
		for (; i < file_num-1; i++){
			FILE *fpw = fopen(patches[i], "wb");
			int j = 0;
			for (; j < part; j++){
				//边读边写
				fputc(fgetc(fpr), fpw);
			}

			fclose(fpw);
		}
		//the last one
		int last_part = filesize - (file_num - 1)*part;
		FILE *fpw = fopen(patches[file_num-1], "wb");
		i = 0;
		for (; i < last_part; i++){
			fputc(fgetc(fpr), fpw);
			fclose(fpw);
		}
	}
	//关闭被分割的总文件
	fclose(fpr);


	//释放内存
	int j = 0;
	for (; j < file_num; j++){
		free(patches[j]);
	}
	free(patches);

	(*env)->ReleaseStringUTFChars(env, path_jstr, path);
	(*env)->ReleaseStringUTFChars(env, path_pattern_jstr, path_pattern);

}


//合并
JNIEXPORT void JNICALL Java_com_dongnaoedu_jni_JniTest_patch
(JNIEnv *env, jclass jcls, jstring path_pattern_jstr, jint file_num, jstring merge_path_jstr)
{
	//合并之后的文件
	const char* merge_path = (*env)->GetStringUTFChars(env, merge_path_jstr, NULL);
	const char* path_pattern = (*env)->GetStringUTFChars(env, path_pattern_jstr, NULL);


	//得到分割之后的文件的路径列表
	char **patches = malloc(sizeof(char*)*file_num);
	int i = 0;
	for (; i < file_num; i++){
		printf("diff:%d \n", 2);
		patches[i] = malloc(sizeof(char)* 100);
		//元素赋值
		//C://jason/ly.png
		//子文件 C://jason/ly_%d.png
		sprintf(patches[i], path_pattern, (i + 1));
	}

	FILE *fpw = fopen(merge_path, "wb");

	//把所有的分割文件读取以便，写入一个总的文件中
	i = 0;
	for (; i < file_num; i++){
		//每个子文件的大小
		int filesize = get_file_size(patches[i]);
		FILE *fpr = fopen(patches[i], "rb");
		int j = 0;
		for (; j < filesize; j++){
			fputc(fgetc(fpr), fpw);
			
		}
		fclose(fpr);
	}
	fclose(fpw);



	(*env)->ReleaseStringUTFChars(env, merge_path_jstr, merge_path);
	(*env)->ReleaseStringUTFChars(env, path_pattern_jstr, path_pattern);
}

 

4、加载生成的.dll文件，并调用

（1）调用文件拆分的方法

String path = "E:\\message.mp4";
String path_pattern = "E:\\message%d.mp4";
t.diff(path, path_pattern,3);

 

运行后将message拆分成了message1、message2、message3三个文件

 

（2）合并后生成了目标文件dest_message

String path_pattern = "E:\\message%d.mp4";
String dest_path = "E:\\dest_message.mp4";
t.patch(path_pattern,3,dest_path);