编写一段java 代码 实现 XXTEA加密解密

以下是 Java XXTEA 加密解密的示例代码：

import java.io.UnsupportedEncodingException;

public class XXTEA {

    private static int delta = 0x9E3779B9;

    private static int[] toIntArray(byte[] data, boolean includeLength) {
        int n = (((data.length & 3) == 0) ? (data.length >>> 2) : ((data.length >>> 2) + 1));
        int[] result;
        if (includeLength) {
            result = new int[n + 1];
            result[n] = data.length;
        } else {
            result = new int[n];
        }
        int i;
        for (i = 0; i < data.length; i++) {
            result[i >>> 2] |= (0x000000ff & data[i]) << ((i & 3) << 3);
        }
        return result;
    }

    private static byte[] toByteArray(int[] data, boolean includeLength) {
        int n = data.length << 2;
        if (includeLength) {
            int m = data[data.length - 1];
            n -= 4;
            if ((m < n - 3) || (m > n)) {
                return null;
            }
            n = m;
        }
        byte[] result = new byte[n];
        for (int i = 0; i < n; i++) {
            result[i] = (byte) ((data[i >>> 2] >>> ((i & 3) << 3)) & 0xff);
        }
        return result;
    }

    private static int mx(int sum, int y, int z, int p, int e, int[] k) {
        return ((z >>> 5 ^ y << 2) + (y >>> 3 ^ z << 4)) ^ ((sum ^ y) + (k[(p & 3) ^ e] ^ z));
    }

    public static byte[] encrypt(byte[] data, byte[] key) {
        if (data.length == 0) {
            return data;
        }
        return toByteArray(encrypt(toIntArray(data, true), toIntArray(key, false)), false);
    }

    public static byte[] decrypt(byte[] data, byte[] key) {
        if (data.length == 0) {
            return data;
        }
        return toByteArray(decrypt(toIntArray(data, false), toIntArray(key, false)), true);
    }

    public static int[] encrypt(int[] v, int[] k) {
        int n = v.length - 1;
        if (n < 1) {
            return v;
        }
        if (k.length < 4) {
            int[] key = new int[4];
            System.arraycopy(k, 0, key, 0, k.length);
            k = key;
        }
        int z = v[n], y = v[0], sum = 0, e, p, q = 6 + 52 / (n + 1);
        while (q-- > 0) {
            sum += delta;
            e = sum >>> 2 & 3;
            for (p = 0; p < n; p++) {
                y = v[p + 1];
                z = v[p] += mx(sum, y, z, p, e, k);
            }
            y = v[0];
            z = v[n] += mx(sum, y, z, p, e, k);
        }
        return v;
    }

    public static int[] decrypt(int[] v, int[] k) {
        int n = v.length - 1;
        if (n < 1) {
            return v;
        }
        if (k.length < 4) {
            int[] key = new int[4];
            System.arraycopy(k, 0, key, 0, k.length);
            k = key;
        }
        int z = v[n], y = v[0], sum, e, p, q = 6 + 52 / (n + 1);
        sum = q * delta;
        while (sum != 0) {
            e = sum >>> 2 & 3;
            for (p = n; p > 0; p--) {
                z = v[p - 1];
                y = v[p] -= mx(sum, y, z, p, e, k);
            }
            z = v[n];
            y = v[0] -= mx(sum, y, z, p, e, k);
            sum -= delta;
        }
        return v;
    }

    public static void main(String[] args) throws UnsupportedEncodingException {
        String data = "Hello, world!";
        String key = "1234567890abcdef";
        byte[] encrypted = encrypt(data.getBytes("UTF-8"), key.getBytes("UTF-8"));
        byte[] decrypted = decrypt(encrypted, key.getBytes("UTF-8"));
        System.out.println("Encrypted: " + new String(encrypted, "UTF-8"));
        System.out.println("Decrypted: " + new String(decrypted, "UTF-8"));
    }
}

以上代码中，`encrypt` 方法用于加密数据，`decrypt` 方法用于解密数据。在加密和解密时，需要指定加密密钥。在示例代码中，密钥使用字符串表示，然后转换为字节数组。加密和解密方法的输入和输出都是字节数组。在主函数中，我们对一个字符串进行加密和解密，并打印出加密和解密后的结果。