md5加密

MD5加密：

 

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

public static String md5(String text) {
		MessageDigest msgDigest = null;

		try {
			msgDigest = MessageDigest.getInstance("MD5");
		} catch (NoSuchAlgorithmException e) {
			throw new IllegalStateException(
					"System doesn't support MD5 algorithm.");
		}

		try {
			msgDigest.update(text.getBytes("GBK"));

		} catch (UnsupportedEncodingException e) {

			throw new IllegalStateException(
					"System doesn't support your  EncodingException.");

		}

		byte[] bytes = msgDigest.digest();

		String md5Str = new String(encodeHex(bytes));

		return md5Str;
	}

	public static char[] encodeHex(byte[] data) {

		int l = data.length;

		char[] out = new char[l << 1];

		// two characters form the hex value.
		for (int i = 0, j = 0; i < l; i++) {
			out[j++]=Character.forDigit((data[i] & 240)>>4, 16);
			out[j++]=Character.forDigit(data[i] & 15, 16);
或者：
//			out[j++] = DIGITS[(0xF0 & data[i]) >>> 4];
//			out[j++] = DIGITS[0x0F & data[i]];
		}

		return out;
	}

 

 

 

public static String MD5(String value) {
		if (null == value || "".equals(value.toString().trim())) {
			return "";
		}
		StringBuffer result = new StringBuffer("");
		try {
			MessageDigest md = MessageDigest.getInstance("MD5");
			md.update(value.getBytes());
			byte[] bt = md.digest();
			int idx = 0;
			for (int i = 0; i < bt.length; i++) {
				idx = bt[i];
				if (idx < 0) {
					idx += 256;
				}
				if (idx < 16) {
					result.append("0");
				}
				result.append(Integer.toHexString(idx));
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return result.toString();
	}
    public static String md5(String str,String charset) {
        if (str == null)
            return null;
        char hexDigits[] = { '0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
                'a', 'b', 'c', 'd', 'e', 'f' };
       
        MessageDigest md5MessageDigest = null;
        byte[] md5Bytes = null;
        char md5Chars[] = null;
        byte[] strBytes = null;
        try {
            strBytes = str.getBytes(charset);
            md5MessageDigest = MessageDigest.getInstance("MD5");
            md5MessageDigest.update(strBytes);
            md5Bytes = md5MessageDigest.digest();
            int j = md5Bytes.length;
            md5Chars = new char[j * 2];
            int k = 0;
            for (int i = 0; i < j; i++) {
                byte md5Byte = md5Bytes[i];
                md5Chars[k++] = hexDigits[md5Byte >>> 4 & 0xf];
                md5Chars[k++] = hexDigits[md5Byte & 0xf];
            }
            return new String(md5Chars);
        } catch (NoSuchAlgorithmException e) {
            //Log.output(e.toString(), Log.STD_ERR);
            return null;
        } catch (UnsupportedEncodingException e) {
            //Log.output(e.toString(), Log.STD_ERR);
            return null;
        } finally {
            md5MessageDigest = null;
            strBytes = null;
            md5Bytes = null;
        }
    }
	
	public static void main(String [] args) throws UnsupportedEncodingException{
		System.out.println(M5.MD5("测试用户_2"));
		System.out.println(M5.md5("测试用户_2","utf-8"));
		System.out.println(URLEncoder.encode("测试用户_2","utf-8"));
	}