package com.yssh.utils;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;

public class FileUtils {
    public final static int SIXTEEN = 16;

    public static final char[] HEX_DIGITS = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};

    @SuppressWarnings("unused")
    public static String getFileMd5(String filePath) {
        FileInputStream fis = null;
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");

            fis = new FileInputStream(new File(filePath));
            FileChannel fChannel = fis.getChannel();
            ByteBuffer buffer = ByteBuffer.allocateDirect(1024 * 1024);

            while (fChannel.read(buffer) != -1) {
                buffer.flip();
                md.update(buffer);
                buffer.compact();
            }
            byte[] b = md.digest();

            return byteToHexString(b);
        } catch (Exception ex) {
            ex.printStackTrace();
            return null;
        } finally {
            try {
                if (null != fis) {
                    fis.close();
                }
            } catch (IOException ex) {
                ex.printStackTrace();
            }
        }
    }

    public static String byteToHexString(byte[] tmp) {
        char[] str = new char[16 * 2];

        int k = 0;
        for (int i = 0; i < SIXTEEN; i++) {
            byte byte0 = tmp[i];
            str[k++] = HEX_DIGITS[byte0 >>> 4 & 0xf];
            str[k++] = HEX_DIGITS[byte0 & 0xf];
        }

        return new String(str);
    }
}