在Java中使用AES加密时，由于加密过程会增加文件的字节数，因此加密后的文件大小会有所变化。为了解决这个问题，可以在加密过程中进行压缩，减小加密后文件的大小。

以下是使用Java代码实现 AES 加密并压缩的示例：

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.zip.DeflaterOutputStream;
import java.util.zip.InflaterInputStream;
import javax.crypto.Cipher;
import javax.crypto.CipherInputStream;
import javax.crypto.CipherOutputStream;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;

public class AESFileEncryptor {
    
    private static final String FILENAME = "plaintext.txt";
    private static final String ENCRYPTED_FILENAME = "encrypted.dat";
    private static final String DECRYPTED_FILENAME = "decrypted.txt";
    private static final String KEY = "0123456789abcdef"; // 16-byte key
    private static final String IV = "abcdef0123456789"; // 16-byte initialization vector
    
    public static void main(String[] args) {
        try {
            // read plaintext file
            FileInputStream inputFile = new FileInputStream(FILENAME);
            byte[] inputData = new byte[inputFile.available()];
            inputFile.read(inputData);
            inputFile.close();
            
            // compress plaintext data
            DeflaterOutputStream compressedOutput = new DeflaterOutputStream(new FileOutputStream(ENCRYPTED_FILENAME));
            compressedOutput.write(inputData);
            compressedOutput.close();
            
            // encrypt compressed data
            byte[] keyBytes = KEY.getBytes();
            SecretKeySpec secretKeySpec = new SecretKeySpec(keyBytes, "AES");
            IvParameterSpec ivParameterSpec = new IvParameterSpec(IV.getBytes());
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS5Padding");
            cipher.init(Cipher.ENCRYPT_MODE, secretKeySpec, ivParameterSpec);
            CipherOutputStream cipherOutput = new CipherOutputStream(new FileOutputStream(ENCRYPTED_FILENAME), cipher);
            FileInputStream encryptedInput = new FileInputStream(ENCRYPTED_FILENAME);
            byte[] buffer = new byte[2048];
            int bytesRead;
            while ((bytesRead = encryptedInput.read(buffer)) != -1) {
                cipherOutput.write(buffer, 0, bytesRead);
            }
            encryptedInput.close();
            cipherOutput.flush();
            cipherOutput.close();
            
            // decrypt encrypted data
            cipher.init(Cipher.DECRYPT_MODE, secretKeySpec, ivParameterSpec);
            CipherInputStream cipherInput = new CipherInputStream(new FileInputStream(ENCRYPTED_FILENAME), cipher);
            InflaterInputStream decompressedInput = new InflaterInputStream(cipherInput);
            FileOutputStream decryptedOutput = new FileOutputStream(DECRYPTED_FILENAME);
            buffer = new byte[2048];
            while ((bytesRead = decompressedInput.read(buffer)) != -1) {
                decryptedOutput.write(buffer, 0, bytesRead);
            }
            decryptedOutput.close();
            decompressedInput.close();
            cipherInput.close();
            
            System.out.println("File encrypted and decrypted successfully.");
        } catch (IOException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

}

在上面的代码中，我们首先读取明文文件并压缩它，然后使用 AES 加密压缩后的数据。在解密时，我们首先使用 AES 解密出被压缩的数据，然后解压缩以获取原始数据。最后，我们将解密后的明文写入文件中。

需要注意的是，在解密之前，我们需要使用相同的密