使用分组加密算法CBC，用Java编程实现对任意大小文件的加解密。完整代码

由于加解密涉及到文件读写操作，因此需要使用Java的IO流。CBC模式需要一个初始向量，可以随机生成，也可以使用固定值。以下是完整代码：

import javax.crypto.*;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.io.*;

public class CBCEncryptDecrypt {
    private static final String ALGORITHM = "AES/CBC/PKCS5Padding";
    private static final int BUFFER_SIZE = 1024 * 1024;

    public static void encrypt(String inputFilePath, String outputFilePath, String key, String iv) throws Exception {
        SecretKeySpec secretKey = new SecretKeySpec(key.getBytes(), "AES");
        IvParameterSpec ivParameterSpec = new IvParameterSpec(iv.getBytes());

        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, secretKey, ivParameterSpec);

        try (InputStream inputStream = new FileInputStream(inputFilePath);
             OutputStream outputStream = new FileOutputStream(outputFilePath)) {
            byte[] buffer = new byte[BUFFER_SIZE];
            int bytesRead;
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                byte[] encryptedBytes = cipher.update(buffer, 0, bytesRead);
                outputStream.write(encryptedBytes);
            }
            byte[] finalBytes = cipher.doFinal();
            outputStream.write(finalBytes);
        }
    }

    public static void decrypt(String inputFilePath, String outputFilePath, String key, String iv) throws Exception {
        SecretKeySpec secretKey = new SecretKeySpec(key.getBytes(), "AES");
        IvParameterSpec ivParameterSpec = new IvParameterSpec(iv.getBytes());

        Cipher cipher = Cipher.getInstance(ALGORITHM);
        cipher.init(Cipher.DECRYPT_MODE, secretKey, ivParameterSpec);

        try (InputStream inputStream = new FileInputStream(inputFilePath);
             OutputStream outputStream = new FileOutputStream(outputFilePath)) {
            byte[] buffer = new byte[BUFFER_SIZE];
            int bytesRead;
            while ((bytesRead = inputStream.read(buffer)) != -1) {
                byte[] decryptedBytes = cipher.update(buffer, 0, bytesRead);
                outputStream.write(decryptedBytes);
            }
            byte[] finalBytes = cipher.doFinal();
            outputStream.write(finalBytes);
        }
    }

    public static void main(String[] args) throws Exception {
        String inputFilePath = "input.txt";
        String encryptedFilePath = "encrypted.bin";
        String decryptedFilePath = "decrypted.txt";
        String key = "0123456789abcdef";
        String iv = "fedcba9876543210";

        encrypt(inputFilePath, encryptedFilePath, key, iv);
        decrypt(encryptedFilePath, decryptedFilePath, key, iv);
    }
}

在main方法中，我们指定了输入文件、加密后的输出文件、解密后的输出文件、密钥和初始向量。可以根据实际情况修改这些参数。在encrypt方法和decrypt方法中，我们使用了Java的try-with-resources语句来自动关闭文件流。加解密的过程中，我们使用了Cipher类和SecretKeySpec类来进行加解密操作。在加密过程中，我们使用了update方法来逐步加密数据，并在最后使用doFinal方法来处理最后一块数据。在解密过程中，我们也采用了类似的方法来逐步解密数据。