Flutter-打印输出(获取文件路径行号等信息扩展)

使用案例

"打印测试".log();
123.log();
null.toString().log();

打印输出内容

普通文本输出结果
flutter: 
=========================开始===========================
文件路径:package:flutter_component/page/demo/notification_center_page.dart
相关信息:_State._contentView. -> 46行 
输出内容:打印测试
=========================结束===========================
flutter: 
=========================开始===========================
文件路径:package:flutter_component/page/demo/notification_center_page.dart
相关信息:_State._contentView. -> 47行 
输出内容:123
=========================结束===========================
flutter: 
=========================开始===========================
文件路径:package:flutter_component/page/demo/notification_center_page.dart
相关信息:_State._contentView. -> 48行 
输出内容:null
=========================结束===========================

image.png

源码

extension StringExtension on String {
  /// 打印
  void log({CustomTrace info}) {
    info ??= CustomTrace(StackTrace.current);
    if (info?.filePath != null) {
      LogUtil.v(
          "文件路径:${info.filePath}\n相关信息:${info.methodName} -> ${info.lineNumber}行 \n输出内容:$this");
    } else {
      print(
          "\n=========================开始===========================\ncontent:$this\n=========================结束===========================");
    }
  }
}
extension ObjectExtension on Object {
  void lod() {
    String string = this.toString();
    string.log(info: CustomTrace(StackTrace.current));
  }
}

class CustomTrace {
  final StackTrace _trace;
  /// 行号
  int lineNumber;
  /// 列号(没啥用)
  int columnNumber;
  /// 文件路径
  String filePath;
  /// 方法名
  String methodName = "";

  CustomTrace(this._trace) {
    _parseTrace();
  }

  void _parseTrace() {
    var list = this._trace.toString().split("\n");
    var traceString = list.first;
    if (list.length > 1) traceString = list[1]; // 有多个时去掉扩展这一层
    /// 过滤特殊符号
    traceString = traceString.replaceAll("#1      ", "");
    traceString = traceString.replaceAll(")", "");

    var info = traceString.split(" (");
    /// 方法名
    methodName = info.first;

    var pathInfo = info.last;

    try {
      var tmp = pathInfo.split(":");
      if (tmp.last is int) {
        /// 列号
        columnNumber = int.parse(tmp.last.toString());
      }
      tmp.removeLast();
      if (tmp.last is int) {
        /// 行号
        lineNumber = int.parse(tmp.last.toString());
      }
      tmp.removeLast();
      /// 文件路径
      filePath = tmp.join(":");
    } catch (e) {
      filePath = pathInfo;
    }
    // print("\n列号:${columnNumber}\n行号:${lineNumber}\n文件路径:${filePath}");
  }
}

class LogUtil {
  static int _limitLength = 900;

  static void init({int limitLength}) {
    _limitLength = limitLength ??= _limitLength;
  }

  static void v(dynamic obj) {
    _log(obj.toString());
  }

  static void _log(String msg) {
    var tmp =
        "\n=========================开始===========================\n${msg}\n=========================结束===========================\n";
    if (tmp.length < _limitLength) {
      print(tmp);
    } else {
      segmentationLog(tmp);
    }
  }

  static void segmentationLog(String msg) {
    var outStr = StringBuffer();
    for (var index = 0; index < msg.length; index++) {
      outStr.write(msg[index]);
      if (index % _limitLength == 0 && index != 0) {
        outStr.clear();
        var lastIndex = index + 1;
        if (msg.length - lastIndex < _limitLength) {
          var remainderStr = msg.substring(lastIndex, msg.length);
          print(remainderStr);
          break;
        }
      }
    }
  }
}

踩坑(因为刚学Flutter 代码啥的都是百度的)

因为是扩展越简单越方便 怎么简单怎么来 那么我们想获取的信息可能会存在异常 如下:
从使用上来说 每次都需要携带StackTrace.current堆栈信息是比较麻烦的所以我将其写在了方法内部 但是问题来了 这样获取的最前面一个信息是当前的扩展信息

CustomTrace info = CustomTrace(StackTrace.current);

百度方法打印

void _parseTrace() {
    var list = this._trace.toString().split("\n");
    var traceString = list.first;
    var indexOfFileName = traceString.indexOf(RegExp(r'[A-Za-z_]+.dart'));
    var fileInfo = traceString.substring(indexOfFileName);
    var listOfInfos = fileInfo.split(":");
    this.fileName = listOfInfos[0];
    this.lineNumber = int.parse(listOfInfos[1]);
    var columnStr = listOfInfos[2];
    columnStr = columnStr.replaceFirst(")", "");
    this.columnNumber = int.parse(columnStr);
  }

输出一直异常 一直定位到扩展

flutter: 
=========================开始===========================
文件: extension.dart -> 9行 
内容: 参数:{}
=========================结束===========================

我们来打印信息看看

 void _parseTrace() {
    print(this._trace.toString()); // 打印信息
    ...
  }

输出结果(从以下结果可以看出最前面一个一直会是我们的扩展, 而真实想要的信息是第二个)

flutter: 
#0      StringExtension.log (package:flutter_demo/extension/extension.dart:9:47)
#1      _MyAppState.routeFactory (package:flutter_demo/main.dart:55:32)
#2      routeFactoryWrapper. (package:flutter_boost/src/boost_navigator.dart:17:29)
#3      BoostPage.create (package:flutter_boost/src/flutter_boost_app.dart:638:55)
#4      new BoostContainer (package:flutter_boost/src/boost_container.dart:14:26)
#5      FlutterBoostAppState._createContainer (package:flutter_boost/src/flutter_boost_app.dart:178:12)
#6      FlutterBoostAppState.initState (package:flutter_boost/src/flutter_boost_app.dart:91:9)
#7      StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:4723:57)
#8      ComponentElement.mount (package:flutter/src/widgets/framework.dart:4556:5)
#9      Element.inflateWidget (package:flutter/src/widgets/framework.dart:3631:14)
#10     Element.updateChild (package:flutter/src/widgets/framework.dart:3383:18)
#11     ComponentElement.performRebuil<…>

改进写法(把自己这一层排除掉OK)

void _parseTrace() {
    var list = this._trace.toString().split("\n");
    var traceString = list.first;
    if (list.length > 1) traceString = list[1]; // 有多个时去掉扩展这一层
    var indexOfFileName = traceString.indexOf(RegExp(r'[A-Za-z_]+.dart'));
    var fileInfo = traceString.substring(indexOfFileName);
    print("打印" + this._trace.toString());
    var listOfInfos = fileInfo.split(":");
    this.fileName = listOfInfos[0];
    this.lineNumber = int.parse(listOfInfos[1]);
    var columnStr = listOfInfos[2];
    columnStr = columnStr.replaceFirst(")", "");
    this.columnNumber = int.parse(columnStr);
  }

参考https://www.jianshu.com/p/54f0efc2b606