flutter开发实战-日志logger写入文件及print

在开发中，需要日志logger写入文件，方便日后查看出现的问题。这里记录之前的实现方案。
使用的日志插件是logger

一、引入日志插件

在工程中pubspec.yaml引入logger

logger: ^1.4.0

二、代码实现

使用比较简单，只需创建一个Logger实例并开始日志记录：

var logger = Logger();

logger.d("Logger is working!");

也可以传递其他对象，如List、Map或Set，而不是字符串消息。

2.1 日志logger_manager

• 使用logger时候，配置logger

FileOutput fileOutPut = FileOutput();
    ConsoleOutput consoleOutput = ConsoleOutput();
    List<LogOutput> multiOutput = [fileOutPut, consoleOutput];
    logger = Logger(
      filter: DevelopmentFilter(),
      // Use the default LogFilter (-> only log in debug mode)
      // printer: SimplePrinter(
      //   colors: true,
      //   printTime: true,
      // ),
      printer: HybridPrinter(
        PrettyPrinter(
          noBoxingByDefault: false,
          methodCount: 2,
          // number of method calls to be displayed
          errorMethodCount: 8,
          // number of method calls if stacktrace is provided
          lineLength: 120,
          // width of the output
          colors: true,
          // Colorful log messages
          printEmojis: false,
          // Print an emoji for each log message
          printTime: true, // Should each log print contain a timestamp
        ),
        debug: SimplePrinter(),
      ),

• 写入文件的FileOutPut，其中用到了IOSink

IOSink可以方便将字节和文本输出，IOSink将字节的StreamSsink与StringSink组合，并且允许容易地输出字节和文本。

/// Writes the log output to a file.
class FileOutput extends LogOutput {
    
  final bool overrideExisting;
  final Encoding encoding;
  IOSink? _sink;

  File? file;
  String? _currentDate;

  FileOutput({
    
    this.overrideExisting = false,
    this.encoding = utf8,
  });

  Future<void> getDirectoryForLogRecord() async {
    
    String currentDate = getCurrentDay();
    if (currentDate != _currentDate) {
    
      final String fileDir = await createDirectory();
      file = File('${
      fileDir}/${
      currentDate}.log');

      _sink = file!.openWrite(
        mode: overrideExisting ? FileMode.writeOnly : FileMode.writeOnlyAppend,
        encoding: encoding,
      );

      _currentDate = currentDate;
    }
  }

  String getCurrentDay() {
    
    String currentDate =
        DateUtil.formatDate(DateTime.now(), format: "yyyyMMdd");
    return currentDate;
  }

  @override
  void init() {
    
    directoryLogRecord(onCallback: () {
    });
  }

  void directoryLogRecord({
    required Function onCallback}) {
    
    getDirectoryForLogRecord().whenComplete(() {
    
      onCallback();
    });
  }

  @override
  void output(OutputEvent event) {
    
    directoryLogRecord(onCallback: () {
    
      if (_sink != null) {
    
        if (Level.info == event.level ||
            Level.warning == event.level ||
            Level.error == event.level) {
    
          _sink?.writeAll(event.lines, '\n');
        }
      }
    });
  }

  @override
  void destroy() async {
    
    await _sink?.flush();
    await _sink?.close();
  }
}

• 实现使用logger_manager

Future<String> createDirectory() async {
    
  final Directory directory = await getApplicationDocumentsDirectory();
  var file = Directory(directory.path+"/"+"lyd");
  try {
    
    bool exist = await file.exists();
    if (exist == false) {
    
      await file.create();
    }
  } catch(e) {
    
    print("createDirectory error");
  }

  return file.path;
}

class LoggerManager {
    
  //私有构造函数
  LoggerManager._internal() {
    
    deleteLogsOfBefore7Day();
    initLogger();
  }

  //保存单例
  static LoggerManager _singleton = LoggerManager._internal();

  //工厂构造函数
  factory LoggerManager() => _singleton;

  late Logger logger;

  // log初始化设置
  Future<void> initLogger() async {
    
    FileOutput fileOutPut = FileOutput();
    ConsoleOutput consoleOutput = ConsoleOutput();
    List<LogOutput> multiOutput = [fileOutPut, consoleOutput];
    logger = Logger(
      filter: DevelopmentFilter(),
      // Use the default LogFilter (-> only log in debug mode)
      // printer: SimplePrinter(
      //   colors: true,
      //   printTime: true,
      // ),
      printer: HybridPrinter(
        PrettyPrinter(
          noBoxingByDefault: false,
          methodCount: 2,
          // number of method calls to be displayed
          errorMethodCount: 8,
          // number of method calls if stacktrace is provided
          lineLength: 120,
          // width of the output
          colors: true,
          // Colorful log messages
          printEmojis: false,
          // Print an emoji for each log message
          printTime: true, // Should each log print contain a timestamp
        ),
        debug: SimplePrinter(),
      ),

      // printer: PrefixPrinter(PrettyPrinter(
      //   noBoxingByDefault: true,
      //   methodCount: 2,
      //   // number of method calls to be displayed
      //   errorMethodCount: 8,
      //   // number of method calls if stacktrace is provided
      //   lineLength: 120,
      //   // width of the output
      //   colors: true,
      //   // Colorful log messages
      //   printEmojis: false,
      //   // Print an emoji for each log message
      //   printTime: true, // Should each log print contain a timestamp
      // )),

      // printer: PrettyPrinter(
      //   noBoxingByDefault: true,
      //   methodCount: 2,
      //   // number of method calls to be displayed
      //   errorMethodCount: 8,
      //   // number of method calls if stacktrace is provided
      //   lineLength: 120,
      //   // width of the output
      //   colors: true,
      //   // Colorful log messages
      //   printEmojis: false,
      //   // Print an emoji for each log message
      //   printTime: true, // Should each log print contain a timestamp
      // ),
      // Use the PrettyPrinter to format and print log
      output: MultiOutput(
        multiOutput,
      ), // Use the default LogOutput (-> send everything to console)
    );
  }

  // Debug
  void debug(String message) {
    
    logger.d(message);
  }

  // verbose
  void verbose(String message) {
    
    logger.v(message);
  }

  // info
  void info(String message) {
    
    logger.i(message);
  }

  // warning
  void warning(String message) {
    
    logger.w(message);
  }

  // error
  void error(String message) {
    
    logger.e(message);
  }

  // 每次启动只保留7天内的日志，删除7天前的日志
  Future<void> deleteLogsOfBefore7Day() async {
    
    final String fileDir = await createDirectory();

    // 获取目录的所有文件
    var dir = Directory(fileDir);
    Stream<FileSystemEntity> file = dir.list();
    await for (FileSystemEntity x in file) {
    
      // 获取文件的的名称
      List<String> paths = x.path.split('/');
      if (paths.isNotEmpty) {
    
        String logName = paths.last.replaceAll('.log', '');
        final logDate = DateUtil.getDateTime(logName);
        final currentDate = DateTime.now();
        //比较相差的天数
        if (logDate != null) {
    
          final difference = currentDate.difference(logDate!).inDays;
          print("deleteLogsOfBefore7Day logDate:${
      logDate}, currentDate:${
      currentDate}, difference:${
      difference}");
          if (difference > 7) {
    
            var file = File(x.path);
            // 删除文件
            file.delete();
          }
        }
      }
    }
  }
}

2.2 在main.dart初始化logger

// 配置logger
  await LoggerManager().initLogger();

2.3 使用LoggerManager

logger的level定义

enum Level {
    
  verbose,
  debug,
  info,
  warning,
  error,
  wtf,
  nothing,
}

可以在需要的地方使用LoggerManager

// verbose:
LoggerManager().verbose("App started at main.dart");

// debug:
LoggerManager().debug("App started at main.dart");

// info:
LoggerManager().info("App started at main.dart");

// warning:
LoggerManager().warning("App started at main.dart");

// error:
LoggerManager().error("App started at main.dart");

// wtf:
LoggerManager().wtf("App started at main.dart");

// nothing:
LoggerManager().nothing("App started at main.dart");

三、小结

flutter开发实战-日志logger写入文件及print，使用的是logger进行实现，输出日志logger的不同level：verbose、debug、info、warning、error、wtf、nothing。

学习记录，每天不停进步。