Flutter日志库logger

logger库

Flutter的 logger库。

小巧、易用且可扩展的日志工具，可打印美观的日志。灵感来源于 Android 的 Logger。

它不仅可以区分等级，还可以打印对象，并自动格式化。

使用

安装

flutter pub add logger

简单使用

创建Logger对象，打印日志：

dart

import 'package:logger/logger.dart';

class HomePage extends HookConsumerWidget {
  const HomePage({super.key});

  final logger = Logger();

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    onclickFoo(){
      logger.i('hello world');
    }
    // ...
  }
}

输出：

可以看到，不同等级的日志，显示为不同的颜色。

配置进阶

全局Logger实例

dart

import 'package:logger/logger.dart';

final gLogger = Logger();

打印样式

通过Logger()构造函数的printer参数，配置打印的样式，该库提供了以下几种Printer：

PrettyPrinter: 突出样式
SimplePrinter: 朴素样式
PrefixPrinter: 包装型Printer，分级别添加固定的前缀
HybridPrinter: 包装型Printer，分级别组合多个Printer
LogfmtPrinter: 输出结构化信息，一般不用于打印，而是存储并分析

效果预览

先创建几个Logger实例，使用不同的Printer，再写一个简单的Widget，使用这些Logger打印，代码如下：

Logger实例Widget测试打印

dart

final prettyLogger = Logger(printer: PrettyPrinter());
final simpleLogger = Logger(printer: SimplePrinter());
final prefixLogger = Logger(printer: PrefixPrinter(SimplePrinter(), trace: '[跟踪]', debug: '[调试]', info: '[信息]', warning: '[警告]', error: '[错误]', fatal: '[灾难]'));
final hybridLogger = Logger(printer: HybridPrinter(SimplePrinter(), error: PrettyPrinter(), fatal: PrettyPrinter()));
final logfmtLogger = Logger(printer: LogfmtPrinter());

dart

class DebugLogger extends StatelessWidget {
  DebugLogger({super.key});

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: Text('Debug Logger')),
      body: Column(
        children: [
          FilledButton(onPressed: _onPressedPretty, child: Text('use Pretty Printer')),
          FilledButton(onPressed: _onPressedSimple, child: Text('use Simple Printer')),
          FilledButton(onPressed: _onPressedPrefix, child: Text('use Prefix Printer')),
          FilledButton(onPressed: _onPressedHybrid, child: Text('use Hybrid Printer')),
          FilledButton(onPressed: _onPressedLogfmt, child: Text('use Logfmt Printer')),
        ],
      ),
    );
  }

  _onPressedPretty() {
    prettyLogger.t('verbose info from pretty printer');
    prettyLogger.d('debug info from pretty printer');
    prettyLogger.i('info info from pretty printer');
    prettyLogger.w('warning info from pretty printer');
    prettyLogger.e('error info from pretty printer');
    prettyLogger.f('fatal info from pretty printer');
  }

  _onPressedSimple() {
    simpleLogger.t('verbose info from simple printer');
    simpleLogger.d('debug info from simple printer');
    simpleLogger.i('info info from simple printer');
    simpleLogger.w('warning info from simple printer');
    simpleLogger.e('error info from simple printer');
    simpleLogger.f('fatal info from simple printer');
  }

  _onPressedPrefix() {
    prefixLogger.t('verbose info from prefix printer');
    prefixLogger.d('debug info from prefix printer');
    prefixLogger.i('info info from prefix printer');
    prefixLogger.w('warning info from prefix printer');
    prefixLogger.e('error info from prefix printer');
    prefixLogger.f('fatal info from prefix printer');
  }

  _onPressedHybrid() {
    hybridLogger.t('verbose info from hybrid printer');
    hybridLogger.d('debug info from hybrid printer');
    hybridLogger.i('info info from hybrid printer');
    hybridLogger.w('warning info from hybrid printer');
    hybridLogger.e('error info from hybrid printer');
    hybridLogger.f('fatal info from hybrid printer');
  }

  _onPressedLogfmt() {
    logfmtLogger.t('verbose info from logfmt printer');
    logfmtLogger.d('debug info from logfmt printer');
    logfmtLogger.i('info info from logfmt printer');
    logfmtLogger.w('warning info from logfmt printer');
    logfmtLogger.e('error info from logfmt printer');
    logfmtLogger.f('fatal info from logfmt printer');
  }
}