对图片md5加密实现

import org.apache.commons.io.FileUtils;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.math.BigInteger;
import java.nio.MappedByteBuffer;
import java.nio.channels.FileChannel;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Md5Util {

    // 将图片转为Md5
    public static String getMd5ByFile(File file) {
        StringBuffer sb = new StringBuffer("");
        try {
            MessageDigest md = MessageDigest.getInstance("MD5");
            md.update(FileUtils.readFileToByteArray(file));
            byte b[] = md.digest();
            int d;
            for (int i = 0; i < b.length; i++) {
                d = b[i];
                if (d < 0) {
                    d = b[i] & 0xff;
                }
                if (d < 16)
                    sb.append("0");
                sb.append(Integer.toHexString(d));
            }
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return sb.toString();
    }
}