//AES CBC解密 func CBCDecrypter(buf []byte, keyStr string) ([]byte, error) { key := sha256.Sum256([]byte(keyStr)) if len(buf)%aes.BlockSize != 0 { return nil, errors.New("plaintext is not a multiple of the block size") } block, err := aes.NewCipher(key[:sha256.Size]) if err != nil { return nil, err } ciphertext := make([]byte, aes.BlockSize+len(buf)) iv := ciphertext[:aes.BlockSize] if _, err := io.ReadFull(rand.Reader, iv); err != nil { return nil, err } mode := cipher.NewCBCDecrypter(block, iv) mode.CryptBlocks(ciphertext[aes.BlockSize:], buf) ciphertext = ciphertext[32:] plain := standardizeDataDe(ciphertext) return plain, nil } func standardizeDataDe(origData []byte) []byte { length := len(origData) unpadding := int(origData[length-1]) if unpadding > length { return nil } return origData[:(length - unpadding)] } func RandKey256() (string, error) { key := make([]byte, 32) if _, err := rand.Read(key); err != nil { return "", err } else { return string(key), nil } } 帮我把这段代码转换成java可运行的

以下是将该段代码转换为Java的示例：

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.util.Arrays;

public class AESCBCDecrypter {
    private static final int BLOCK_SIZE = 16;
    
    public static byte[] cbcDecrypter(byte[] buf, String keyStr) throws Exception {
        byte[] key = sha256(keyStr.getBytes());
        if (buf.length % BLOCK_SIZE != 0) {
            throw new Exception("plaintext is not a multiple of the block size");
        }
        SecretKeySpec secretKeySpec = new SecretKeySpec(Arrays.copyOf(key, BLOCK_SIZE), "AES");
        Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
        byte[] iv = new byte[BLOCK_SIZE];
        SecureRandom random = new SecureRandom();
        random.nextBytes(iv);
        cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, new IvParameterSpec(iv));
        byte[] ciphertext = cipher.doFinal(buf);
        return standardizeDataDe(Arrays.copyOfRange(ciphertext, BLOCK_SIZE, ciphertext.length));
    }
    
    public static byte[] sha256(byte[] bytes) throws NoSuchAlgorithmException {
        MessageDigest digest = MessageDigest.getInstance("SHA-256");
        return digest.digest(bytes);
    }
    
    public static byte[] standardizeDataDe(byte[] origData) {
        int length = origData.length;
        int unpadding = origData[length - 1];
        if (unpadding > length) {
            return null;
        }
        return Arrays.copyOfRange(origData, 0, length - unpadding);
    }
    
    public static String randKey256() {
        byte[] key = new byte[32];
        SecureRandom random = new SecureRandom();
        random.nextBytes(key);
        return new String(key);
    }
}

请注意，Java中没有直接的方法可以将字节数组转换为字符串，因此使用了`new String(key)`的方式。但是，请注意这种方式可能会导致不可预测的结果，因为它会使用默认字符集（通常是UTF-8）。因此，建议使用`Base64`编码来将字节数组转换为字符串。