NDK开发:文件拆分和合并
2019-09-18 本文已影响0人
小村医
一、拆分文件
//获取文件大小
long get_file_size(char *path) {
FILE *fp = fopen(path, "rb");
fseek(fp, 0, SEEK_END);
return ftell(fp);
}
JNIEXPORT void JNICALL Java_com_binzi_ndkfile_NDKFileUtils_split
(JNIEnv *env, jclass jcls, jstring path_jstr,jstring path_pattern_jstr, jint file_num){
//jstring -> char*
//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);
//得到分割之后的子文件的路径列表
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
sprintf(patches[i], path_pattern, (i+1));
LOGI("patch path:%s",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;
//逐一写入不同的分割子文件中
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 {
//不整除
int part = filesize / (file_num - 1);
i = 0;
//逐一写入不同的分割子文件中
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
FILE *fpw = fopen(patches[file_num - 1], "wb");
i = 0;
for(; i < filesize % (file_num - 1); i++){
fputc(fgetc(fpr),fpw);
}
fclose(fpw);
}
//关闭被分割的文件
fclose(fpr);
//释放
i = 0;
for(; i < file_num; i++){
free(patches[i]);
}
free(patches);
(*env)->ReleaseStringUTFChars(env,path_jstr,path);
(*env)->ReleaseStringUTFChars(env,path_pattern_jstr,path_pattern);
}
二、文件合并
JNIEXPORT void JNICALL Java_com_binzi_ndkfile_NDKFileUtils_merge
(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);
//分割子文件的pattern
const char* path_pattern = (*env)->GetStringUTFChars(env,path_pattern_jstr,NULL);
//得到分割之后的子文件的路径列表
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
sprintf(patches[i], path_pattern, (i+1));
LOGI("patch path:%s",patches[i]);
}
FILE *fpw = fopen(merge_path,"wb");
//把所有的分割文件读取一遍,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);
//释放
i = 0;
for(; i < file_num; i++){
free(patches[i]);
}
free(patches);
(*env)->ReleaseStringUTFChars(env,path_pattern_jstr,path_pattern);
(*env)->ReleaseStringUTFChars(env,merge_path_jstr,merge_path);
}