- 原因
保证服务器下发的资源在下载后没有修改，检测完整行
- ios代码 检验文件流
#define FileHashDefaultChunkSizeForReadingData 1024*8
#pragma mark 大文件的md5
-(NSString*)getFileMD5WithPath:(NSString*)path
{
return (__bridge_transfer NSString *)FileMD5HashCreateWithPath((__bridge CFStringRef)path, FileHashDefaultChunkSizeForReadingData);
}
CFStringRef FileMD5HashCreateWithPath(CFStringRef filePath,size_t chunkSizeForReadingData) {
// Declare needed variables
CFStringRef result = NULL;
CFReadStreamRef readStream = NULL;
// Get the file URL
CFURLRef fileURL =
CFURLCreateWithFileSystemPath(kCFAllocatorDefault,
(CFStringRef)filePath,
kCFURLPOSIXPathStyle,
(Boolean)false);
if (!fileURL) goto done;
// Create and open the read stream
readStream = CFReadStreamCreateWithFile(kCFAllocatorDefault,
(CFURLRef)fileURL);
if (!readStream) goto done;
bool didSucceed = (bool)CFReadStreamOpen(readStream);
if (!didSucceed) goto done;
// Initialize the hash object
CC_MD5_CTX hashObject;
CC_MD5_Init(&hashObject);
// Make sure chunkSizeForReadingData is valid
if (!chunkSizeForReadingData) {
chunkSizeForReadingData = FileHashDefaultChunkSizeForReadingData;
}
// Feed the data to the hash object
bool hasMoreData = true;
while (hasMoreData) {
uint8_t buffer[chunkSizeForReadingData];
CFIndex readBytesCount = CFReadStreamRead(readStream,(UInt8 *)buffer,(CFIndex)sizeof(buffer));
if (readBytesCount == -1) break;
if (readBytesCount == 0) {
hasMoreData = false;
continue;
}
CC_MD5_Update(&hashObject,(const void *)buffer,(CC_LONG)readBytesCount);
}
// Check if the read operation succeeded
didSucceed = !hasMoreData;
// Compute the hash digest
unsigned char digest[CC_MD5_DIGEST_LENGTH];
CC_MD5_Final(digest, &hashObject);
// Abort if the read operation failed
if (!didSucceed) goto done;
// Compute the string result
char hash[2 * sizeof(digest) + 1];
for (size_t i = 0; i < sizeof(digest); ++i) {
snprintf(hash + (2 * i), 3, "%02x", (int)(digest[i]));
}
result = CFStringCreateWithCString(kCFAllocatorDefault,(const char *)hash,kCFStringEncodingUTF8);
done:
if (readStream) {
CFReadStreamClose(readStream);
CFRelease(readStream);
}
if (fileURL) {
CFRelease(fileURL);
}
return result;
}
- Android文件流md5的相关代码如下：
public static String getMD5(String imagePath) throws NoSuchAlgorithmException, IOException {
InputStream in = new FileInputStream(new File(imagePath));
StringBuffer md5 = new StringBuffer();
MessageDigest md = MessageDigest.getInstance("MD5");
byte[] dataBytes = new byte[1024];
int nread = 0;
while ((nread = in.read(dataBytes)) != -1) {
md.update(dataBytes, 0, nread);
}
byte[] mdbytes = md.digest();
// convert the byte to hex format
for (int i = 0; i < mdbytes.length; i++) {
md5.append(Integer.toString((mdbytes[i] & 0xff) + 0x100, 16).substring(1));
}
return md5.toString().toLowerCase();
}
可以得到一样的md5，如果是对字符串操作的话可能得到的结果就不一样了
