转自：https://blog.csdn.net/starry7953810/article/details/79924156

为什么只有加密，没有解密呢？欢迎大佬留言解答

package utilw;

import java.security.MessageDigest;

public class MD5 {
	/** MD5 */
	private static final String hexDigIts[] = { "0", "1", "2", "3", "4", "5",
			"6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

	/** MD5加密 */
	public static String MD5Encode(String origin, String charsetname) {
		String resultString = null;
		try {
			resultString = new String(origin);
			MessageDigest md = MessageDigest.getInstance("MD5");
			if (null == charsetname || "".equals(charsetname)) {
				resultString = byteArrayToHexString(md.digest(resultString
						.getBytes()));
			} else {
				resultString = byteArrayToHexString(md.digest(resultString
						.getBytes(charsetname)));
			}
		} catch (Exception e) {
		}
		return resultString;
	}

	public static String byteArrayToHexString(byte b[]) {
		StringBuffer resultSb = new StringBuffer();
		for (int i = 0; i < b.length; i++) {
			resultSb.append(byteToHexString(b[i]));
		}
		return resultSb.toString();
	}

	public static String byteToHexString(byte b) {
		int n = b;
		if (n < 0) {
			n += 256;
		}
		int d1 = n / 16;
		int d2 = n % 16;
		return hexDigIts[d1] + hexDigIts[d2];
	}

	public static void main(String[] args) {
		System.out.println(MD5Encode("12345", "utf8"));
	}
}

?