java獲取大檔案的MD5、SHA1,CRC32碼
阿新 • • 發佈:2019-01-23
import org.apache.commons.codec.digest.DigestUtils; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.IOException; import java.nio.MappedByteBuffer; import java.nio.channels.FileChannel; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; import java.util.zip.CRC32; public class FileSafeCode { /** * 計算大檔案 md5獲取getMD5(); SHA1獲取getSha1() CRC32獲取 getCRC32() */ protected static char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f' }; public static MessageDigest messagedigest = null; /** * 對一個檔案獲取md5值 * * @return md5串 * @throws NoSuchAlgorithmException */ public static String getMD5(File file) throws IOException, NoSuchAlgorithmException { messagedigest = MessageDigest.getInstance("MD5"); FileInputStream in = new FileInputStream(file); FileChannel ch = in.getChannel(); MappedByteBuffer byteBuffer = ch.map(FileChannel.MapMode.READ_ONLY, 0, file.length()); messagedigest.update(byteBuffer); return bufferToHex(messagedigest.digest()); } /** * @param target 字串 求一個字串的md5值 * @return md5 value */ public static String StringMD5(String target) { return DigestUtils.md5Hex(target); } /*** * 計算SHA1碼 * * @return String 適用於上G大的檔案 * @throws NoSuchAlgorithmException * */ public static String getSha1(File file) throws OutOfMemoryError, IOException, NoSuchAlgorithmException { messagedigest = MessageDigest.getInstance("SHA-1"); FileInputStream in = new FileInputStream(file); FileChannel ch = in.getChannel(); MappedByteBuffer byteBuffer = ch.map(FileChannel.MapMode.READ_ONLY, 0, file.length()); messagedigest.update(byteBuffer); return bufferToHex(messagedigest.digest()); } /** * 獲取檔案CRC32碼 * * @return String * */ public static String getCRC32(File file) { CRC32 crc32 = new CRC32(); // MessageDigest.get FileInputStream fileInputStream = null; try { fileInputStream = new FileInputStream(file); byte[] buffer = new byte[8192]; int length; while ((length = fileInputStream.read(buffer)) != -1) { crc32.update(buffer, 0, length); } return crc32.getValue() + ""; } catch (FileNotFoundException e) { e.printStackTrace(); return null; } catch (IOException e) { e.printStackTrace(); return null; } finally { try { if (fileInputStream != null) fileInputStream.close(); } catch (IOException e) { e.printStackTrace(); } } } public static String getMD5String(String s) { return getMD5String(s.getBytes()); } public static String getMD5String(byte[] bytes) { messagedigest.update(bytes); return bufferToHex(messagedigest.digest()); } /** * @Description 計算二進位制資料 * @return String * */ private static String bufferToHex(byte bytes[]) { return bufferToHex(bytes, 0, bytes.length); } private static String bufferToHex(byte bytes[], int m, int n) { StringBuffer stringbuffer = new StringBuffer(2 * n); int k = m + n; for (int l = m; l < k; l++) { appendHexPair(bytes[l], stringbuffer); } return stringbuffer.toString(); } private static void appendHexPair(byte bt, StringBuffer stringbuffer) { char c0 = hexDigits[(bt & 0xf0) >> 4]; char c1 = hexDigits[bt & 0xf]; stringbuffer.append(c0); stringbuffer.append(c1); } public static boolean checkPassword(String password, String md5PwdStr) { String s = getMD5String(password); return s.equals(md5PwdStr); } }