logging-framework.md

Designing a Logging Framework

In this article, we will explore the design and development of a Logging Framework in Java, using object-oriented programming principles.

A Logging Framework is crucial for effective monitoring, debugging, and auditing of applications.

System Requirements

The Logging Framework should:

1. Support Multiple Log Levels: Including INFO, DEBUG, WARN, and ERROR.
2. Flexible Log Destination: Enable logging to various outputs like the console, files, or external services.
3. Configurable Formatting: Allow for custom log message formats.
4. Performance Efficiency: Ensure minimal impact on application performance.

Core Use Cases

1. Logging Messages: Ability to log messages at different levels.
2. Configuring Loggers: Setup loggers with varying settings and outputs.
3. Managing Log Output: Direct messages to appropriate destinations based on configurations.

Key Classes:

• Logger: Main interface for logging messages.
• LogLevel: Enum representing log levels.
• LogDestination: Interface for different log output destinations.
• ConsoleDestination, FileDestination: Implementations of the LogDestination interface.

Java Implementation

LogLevel Enum

Defines different levels of logging.

public enum LogLevel {
    INFO, DEBUG, WARN, ERROR
}

LogDestination Interface

Interface for different log destinations.

public interface LogDestination {
    void writeLog(String message);
}

ConsoleDestination Class

Implementation for logging to the console.

public class ConsoleDestination implements LogDestination {
    @Override
    public void writeLog(String message) {
        System.out.println(message);
    }
}

FileDestination Class

Implementation for logging to a file.

import java.io.FileWriter;
import java.io.IOException;

public class FileDestination implements LogDestination {
    private String filename;

    public FileDestination(String filename) {
        this.filename = filename;
    }

    @Override
    public void writeLog(String message) {
        try (FileWriter fileWriter = new FileWriter(filename, true)) {
            fileWriter.write(message + "\n");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Logger Class

Main class for logging operations.

import java.text.SimpleDateFormat;
import java.util.Date;

public class Logger {
    private LogLevel level;
    private LogDestination destination;

    public Logger(LogLevel level, LogDestination destination) {
        this.level = level;
        this.destination = destination;
    }

    public void log(LogLevel level, String message) {
        if (level.ordinal() >= this.level.ordinal()) {
            String timestamp = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss").format(new Date());
            String formattedMessage = timestamp + " [" + level.name() + "] " + message;
            destination.writeLog(formattedMessage);
        }
    }

    // Getters and setters...
}