Java MD5 加密算法

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

public class Md5 {

    // 计算文件MD5值
    public static String getMD5Data(File file) {
        if (!file.exists()) {
            return null;
        }

        try {
            MessageDigest md5 = MessageDigest.getInstance("MD5");

            byte[] buffer = new byte[1024];
            int length = 0;
            FileInputStream fis = new FileInputStream(file);
            while ((length = fis.read(buffer, 0, buffer.length)) != -1) {
                md5.update(buffer, 0, length);
            }

            fis.close();
            return byte2hex(md5.digest()).toLowerCase();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return null;
    }

    // 计算字符串MD5值
    public static String getMD5Data(String content) {
        try {
            byte []src = content.getBytes();
            MessageDigest md5 = MessageDigest.getInstance("MD5");
            md5.update(src);

            return byte2hex(md5.digest()).toLowerCase();
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static String byte2hex(byte[] b) {
        String hs = "";
        String temp = "";
        for (int n = 0; n < b.length; n++) {
            temp = Integer.toHexString(b[n] & 0XFF);
            if (temp.length() == 1) {
                hs = hs + "0" + temp;
            } else {
                hs = hs + temp;
            }
        }

        return hs.toUpperCase();
    }

}