Flutter - 集成三方库:日记(logger)

日记

利用print方法时,会提示

添加依赖

1. $ flutter pub add logger

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下载依赖

1. $ flutter pub get

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利用

打印

1. import 'package:logger/logger.dart';
3. var logger = Logger();
4. logger.d("debug");
5. logger.e("error");
6. logger.i("info");
7. logger.f("fatal");
8. logger.w("warning");
9. logger.t("trace");

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设置打印级别

1. /// The current logging level of the app.
2. /// All logs with levels below this level will be omitted.
3. /// 设置打印级别,低于level的不会被打印
4. Logger.level;

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1. enum Level {
2.   all(0),
3.   @Deprecated('[verbose] is being deprecated in favor of [trace].')
4.   verbose(999),
5.   trace(1000),
6.   debug(2000),
7.   info(3000),
8.   warning(4000),
9.   error(5000),
10.   @Deprecated('[wtf] is being deprecated in favor of [fatal].')
11.   wtf(5999),
12.   fatal(6000),
13.   @Deprecated('[nothing] is being deprecated in favor of [off].')
14.   nothing(9999),
15.   off(10000),
16.   ;
18.   final int value;
20.   const Level(this.value);
21. }

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打印到文件

1. /// 使用 getApplicationDocumentsDirectory 需要
2. /// 添加 path_provider
3. /// flutter pub add path_provider
4. /// flutter pub ge
5. /// - `NSDocumentDirectory` on iOS and macOS.
6. /// - The Flutter engine's `PathUtils.getDataDirectory` API on Android.
7. Directory documentDir = await getApplicationDocumentsDirectory();
8. var logger = Logger(
9.   output: FileOutput(file: File("${documentDir.path}/log.txt")),
10. );

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打印到控制台+文件

1. Directory documentDir = await getApplicationDocumentsDirectory();
2. FileOutput fileOutPut = FileOutput(
3.   file: File("${documentDir.path}/log.txt"),
4. );
5. ConsoleOutput consoleOutput = ConsoleOutput();
6. List<LogOutput> multiOutput = [fileOutPut, consoleOutput];
7. var logger = Logger(
8. output: MultiOutput(multiOutput),
9. );

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打印时间

Logger构造函数有个printer参数可以指定输出格式

1. var logger = Logger(
2.     filter: null, // Use the default LogFilter (-> only log in debug mode)
3.     printer: PrettyPrinter(dateTimeFormat: DateTimeFormat.dateAndTime),
4.     output: MultiOutput(multiOutput),
5. );

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打印过滤器

默认的过滤器(DevelopmentFilter)在debug模式下可以打印所有level >= Logger.level的日记，在Release模式下所有日记被忽略。
好比设置Release模式下只打印warning级别以上(含warning)的日记

1. class MyFilter extends LogFilter {
2.   @override
3.   bool shouldLog(LogEvent event) {
4.     if (event.level.value < Logger.level.value) {
5.       return false;
6.     }
7.     return true;
8.   }
9. }

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1. ...
2. const bool inProduction = bool.fromEnvironment("dart.vm.product");
3. if (inProduction) {
4.   Logger.level = Level.warning;
5. }
6. ...
8. ConsoleOutput consoleOutput = ConsoleOutput();
9.     List<LogOutput> multiOutput = [fileOutPut, consoleOutput];
10.     var logger = Logger(
11.       filter:
12.           MyFilter(), // Use the default LogFilter (-> only log in debug mode)
13.       printer: PrettyPrinter(dateTimeFormat: DateTimeFormat.dateAndTime),
14.       output: MultiOutput(multiOutput),
15. );
17. logger.d("debug");
18. logger.e("error");
19. logger.i("info");
20. logger.f("fatal");
21. logger.w("warning");
22. logger.t("trace");

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参考

• logger
  
• Flutter-文件体系目录和文件读写
  
• Flutter: How to show log output in console and automatically store it?
  
• Flutter中怎样判定当前运行模式是Debug照旧Release