如何正确使用CipherOutputStream加密和解密用log4j创建的日志(RollingFileAppender)

import java.io.FileOutputStream;
import java.io.IOException;
import java.security.GeneralSecurityException;
import java.security.Key;
import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.spec.SecretKeySpec;

import org.apache.log4j.Appender;
import org.apache.log4j.FileAppender;
import org.apache.log4j.Logger;
import org.apache.log4j.PatternLayout;

public class EncryptedLog4jAppender {

    private static final String KEY_ALGORITHM = "AES";
    private static final int KEY_SIZE = 128;
    private static final String CIPHER_ALGORITHM = "AES";

    public static void main(String[] args) throws GeneralSecurityException, IOException {
        // Generate a secret key for encryption
        KeyGenerator keyGenerator = KeyGenerator.getInstance(KEY_ALGORITHM);
        keyGenerator.init(KEY_SIZE);
        Key secretKey = keyGenerator.generateKey();

        // Create a log4j logger with a rolling file appender
        Logger logger = Logger.getLogger(EncryptedLog4jAppender.class);
        Appender appender = createEncryptedRollingFileAppender(secretKey);
        logger.addAppender(appender);

        // Log some messages
        logger.info("This is an encrypted log message.");
        logger.warn("This is another encrypted log message.");

        // Close the logger and appender
        logger.removeAppender(appender);
        appender.close();
    }

    private static Appender createEncryptedRollingFileAppender(Key secretKey) throws GeneralSecurityException, IOException {
        // Create a cipher for encryption
        Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM);
        cipher.init(Cipher.ENCRYPT_MODE, secretKey, new SecureRandom());

        // Create a file output stream for the encrypted log file
        FileOutputStream fos = new FileOutputStream("encrypted.log");
        CipherOutputStream cos = new CipherOutputStream(fos, cipher);

        // Create a rolling file appender with the encrypted output stream
        PatternLayout layout = new PatternLayout("%d{ISO8601} [%t] %-5p %c %x - %m%n");
        RollingFileAppender appender = new RollingFileAppender(layout, null, true);
        appender.setOutputStream(cos);

        return appender;
    }
}