BoxLogger Tutorial

This tutorial provides an overview of the BoxLogger class, which is part of the lightweight-component/aj-util library. The BoxLogger class provides utilities for creating boxed log messages with proper formatting and alignment.

Introduction

The BoxLogger class contains static methods for creating visually formatted log messages in boxes, with support for ANSI colors and proper handling of wide characters (like CJK).

Main Features

• Boxed log message formatting
• ANSI color support
• String truncation with ellipsis
• Display width calculation (handling wide characters)
• String repetition utility

Constants

1. ANSI_GREEN - ANSI green color code
2. ANSI_YELLOW - ANSI yellow color code
3. ANSI_BLUE - ANSI blue color code
4. ANSI_RED - ANSI red color code
5. ANSI_RESET - ANSI reset code
6. NONE - Constant "none"
7. TRACE_KEY - Default trace key name
8. BIZ_ACTION - Default business action key name

Methods

1. Box Formatting

1. boxLine(char left, char fill, char right, String title) - Create a box border line
2. boxContent(String key, String value) - Create a content line within box

2. String Utilities

1. repeat(char c, int n) - Repeat character n times
2. truncate(String s, int maxDisplayLen) - Truncate string with ellipsis
3. getDisplayWidth(String s) - Calculate display width (wide chars = 2)
4. isWideChar(char ch) - Check if character is wide (CJK)

Usage Examples

Create Boxed Log

System.out.println(BoxLogger.boxLine('┌', '─', '┐', " LOG START "));
System.out.println(BoxLogger.boxContent("User: ", "张三"));
System.out.println(BoxLogger.boxLine('└', '─', '┘', " LOG END "));

ANSI Colors

System.out.println(BoxLogger.ANSI_RED + "Error!" + BoxLogger.ANSI_RESET);

String Utilities

String repeated = BoxLogger.repeat('-', 10); // "----------"
String truncated = BoxLogger.truncate("This is a long string", 10); // "This is..."
int width = BoxLogger.getDisplayWidth("中文"); // 4

Implementation Notes

• Box width is fixed at 97 characters
• Properly handles CJK and fullwidth characters
• Includes basic ANSI color support
• Provides clean truncation with ellipsis

Conclusion

The BoxLogger class provides useful utilities for creating visually formatted log messages, especially useful for CLI applications or debugging output.