Java Md5 消息摘要

MD5或者SHA：

public class Md5ShaHash {

<span style="white-space:pre">	</span>private String digestString = null;

	public String digestString(String plaintString, String algorithm) {
		if (algorithm.equals("md5")) {
			digestString = md5(plaintString);
		}
		else {
			digestString = sha(plaintString);
		}
		return digestString;
	}

	public String digestFile(String sourceFileName, String diminationFileName, String algorithm) throws Exception {
		FileInputStream fileInputStream = new FileInputStream(sourceFileName);
		FileOutputStream fileOutputStream = new FileOutputStream(diminationFileName);
		int num = fileInputStream.available();
		byte[] txt = new byte[num];
		fileInputStream.read(txt);
		if (algorithm.equals("md5")) {
			digestString = md5(new String(txt, "UTF-8"));
		}
		else {
			digestString = sha(new String(txt, "UTF-8"));
		}
		fileOutputStream.write(digestString.getBytes());
		fileInputStream.close();
		fileOutputStream.close();
		return digestString;
	}

	// md5加密
	public static String md5(String inputText) {
		return encrypt(inputText, "md5");
	}

	// sha加密
	public String sha(String inputText) {
		return encrypt(inputText, "sha-1");
	}

	/**
	 * md5或者sha-1加密
	 * 
	 * @param inputText
	 *            要加密的内容
	 * @param algorithmName
	 *            . * 加密算法名称：md5或者sha-1，不区分大小写
	 * @return
	 */
	private String encrypt(String inputText, String algorithmName) {
		if (inputText == null || "".equals(inputText.trim())) {
			throw new IllegalArgumentException("请输入要加密的内容");
		}
		if (algorithmName == null || "".equals(algorithmName.trim())) {
			algorithmName = "md5";
		}
		String encryptText = null;
		try {
			MessageDigest m = MessageDigest.getInstance(algorithmName);
			m.update(inputText.getBytes("UTF-8"));
			byte s[] = m.digest();
			return hex(s);
		}
		catch (NoSuchAlgorithmException e) {
			e.printStackTrace();
		}
		catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}
		return encryptText;
	}

	// 返回十六进制字符串
	private String hex(byte[] arr) {
		StringBuffer sb = new StringBuffer();
		for (int i = 0; i < arr.length; ++i) {
			sb.append(Integer.toHexString((arr[i] & 0xFF) | 0x100).substring(1, 3));
		}
		return sb.toString();
	}
}