面试题：Java日志框架扩展与定制

技术点

自定义Appender：Logback允许通过继承AppenderBase类来创建自定义的Appender，用于将日志发送到远程服务器。
加密处理：使用Java的加密库（如JCE，Java Cryptography Architecture）对日志内容进行加密。
网络通信：利用Java的网络编程技术（如Socket、HTTP Client）将加密后的日志发送到远程服务器。
SLF4J绑定：确保自定义的Logback Appender能与SLF4J正确绑定，使项目中的日志调用能使用到新的功能。

实现步骤

创建自定义Appender类

import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.AppenderBase;

public class CustomEncryptedAppender extends AppenderBase<ILoggingEvent> {
    @Override
    protected void append(ILoggingEvent eventObject) {
        // 这里开始处理日志
    }
}

加密日志内容

import javax.crypto.Cipher;
import javax.crypto.KeyGenerator;
import javax.crypto.SecretKey;
import java.nio.charset.StandardCharsets;
import java.security.SecureRandom;

public class EncryptionUtil {
    private static final String ALGORITHM = "AES";
    private static final String TRANSFORMATION = "AES/ECB/PKCS5Padding";

    public static byte[] encrypt(String data, SecretKey secretKey) throws Exception {
        Cipher cipher = Cipher.getInstance(TRANSFORMATION);
        cipher.init(Cipher.ENCRYPT_MODE, secretKey);
        return cipher.doFinal(data.getBytes(StandardCharsets.UTF_8));
    }

    public static SecretKey generateSecretKey() throws Exception {
        KeyGenerator keyGenerator = KeyGenerator.getInstance(ALGORITHM);
        keyGenerator.init(128, new SecureRandom());
        return keyGenerator.generateKey();
    }
}

发送加密日志到远程服务器

使用Socket

import java.io.OutputStream;
import java.net.Socket;

public class RemoteSender {
    public static void send(byte[] encryptedData, String serverAddress, int port) throws Exception {
        try (Socket socket = new Socket(serverAddress, port)) {
            OutputStream outputStream = socket.getOutputStream();
            outputStream.write(encryptedData);
        }
    }
}

使用HTTP Client（以Apache HttpClient为例）

import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ByteArrayEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

public class HttpRemoteSender {
    public static void send(byte[] encryptedData, String serverUrl) throws Exception {
        try (CloseableHttpClient httpClient = HttpClients.createDefault()) {
            HttpPost httpPost = new HttpPost(serverUrl);
            HttpEntity entity = new ByteArrayEntity(encryptedData);
            httpPost.setEntity(entity);
            try (CloseableHttpResponse response = httpClient.execute(httpPost)) {
                EntityUtils.consume(response.getEntity());
            }
        }
    }
}

在自定义Appender中整合加密与发送逻辑

import ch.qos.logback.classic.spi.ILoggingEvent;
import ch.qos.logback.core.AppenderBase;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

public class CustomEncryptedAppender extends AppenderBase<ILoggingEvent> {
    private static final ExecutorService executorService = Executors.newSingleThreadExecutor();
    private String serverAddress;
    private int port;
    private String serverUrl; // 如果使用HTTP

    public void setServerAddress(String serverAddress) {
        this.serverAddress = serverAddress;
    }

    public void setPort(int port) {
        this.port = port;
    }

    public void setServerUrl(String serverUrl) {
        this.serverUrl = serverUrl;
    }

    @Override
    protected void append(ILoggingEvent eventObject) {
        executorService.submit(() -> {
            try {
                String logMessage = eventObject.getFormattedMessage();
                SecretKey secretKey = EncryptionUtil.generateSecretKey();
                byte[] encryptedData = EncryptionUtil.encrypt(logMessage, secretKey);
                if (serverUrl != null) {
                    HttpRemoteSender.send(encryptedData, serverUrl);
                } else {
                    RemoteSender.send(encryptedData, serverAddress, port);
                }
            } catch (Exception e) {
                addError("Failed to send encrypted log", e);
            }
        });
    }
}

配置Logback 在logback.xml中添加自定义Appender的配置：

<configuration>
    <appender name="CUSTOM_ENCRYPTED" class="com.example.CustomEncryptedAppender">
        <serverAddress>your_server_address</serverAddress>
        <port>your_port</port>
        <!-- 如果使用HTTP -->
        <serverUrl>your_http_server_url</serverUrl>
    </appender>
    <root level="info">
        <appender-ref ref="CUSTOM_ENCRYPTED" />
    </root>
</configuration>

确保SLF4J绑定 项目中已经使用SLF4J结合Logback，只要自定义的Logback Appender配置正确，SLF4J就能自动绑定并使用新的Appender来处理日志。例如，项目中的日志调用方式不变：

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

public class SomeClass {
    private static final Logger logger = LoggerFactory.getLogger(SomeClass.class);

    public void someMethod() {
        logger.info("This is a log message");
    }
}

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面试题：Java日志框架扩展与定制

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技术点

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