呵呵……Log4r的想法来源于著名的“Log4j”，这是我java编程生涯中最喜欢的logger。但是log4r的文档真的很差，新手也很难。让我展示我的解决方案：
步骤1。创建 log4r 配置文件：（文件名：config/log4r.yml）
log4r_config:
# define all loggers ...
loggers:
- name : production
level : WARN
trace : 'false'
outputters :
- datefile
- name : development
level : DEBUG
trace : 'true'
outputters :
- datefile
# define all outputters (incl. formatters)
outputters:
- type: DateFileOutputter
name: datefile
dirname: "log"
# notice the file extension is needed!
# if you want the file is named by the process, just comment it,
# then it will automatically get the same name with its process,
# e.g. rails_2017-05-03.log
filename: "my_app.log"
formatter:
date_pattern: '%H:%M:%S'
pattern : '%d %l: %m '
type : PatternFormatter
第2步。修改 config/application.rb
require 'rails/all'
# add these line for log4r
require 'log4r'
require 'log4r/yamlconfigurator'
require 'log4r/outputter/datefileoutputter'
include Log4r
Bundler.require(:default, Rails.env) if defined?(Bundler)
module Zurich
class Application < Rails::Application
#...
# assign log4r's logger as rails' logger.
log4r_config= YAML.load_file(File.join(File.dirname(__FILE__),"log4r.yml"))
YamlConfigurator.decode_yaml( log4r_config['log4r_config'] )
config.logger = Log4r::Logger[Rails.env]
end
end
第三步。将此行添加到您的 Gemfile。
# which is the latest version and support "datefileoutputter"
gem 'log4r', '1.1.9'
（如果您使用的是 Rails 4+（包括 Rails6），还有步骤 4：将此文件添加到 config/initializers 文件夹
# config/initializers/log4r_patch_for_rails4.rb
class Log4r::Logger
def formatter() # for rails4+
Proc.new{|severity, time, progname, msg|
formatted_severity = sprintf("%-5s",severity.to_s)
formatted_time = time.strftime("%Y-%m-%d %H:%M:%S")
"[#{formatted_severity} #{formatted_time} #{$$}]\n #{msg}\n"
}
end
def formatter= temp # for rails6+
end
end
)
完成。现在 "cd" 进入你的 Rails 应用程序文件夹，运行 "bundle" 安装 log4r，然后 "rails s"，你会在 "/log" 文件夹中找到日志文件，如下所示：
May 9 17:05 rails_2011-05-09.log
May 10 13:42 rails_2011-05-10.log
日志内容是（我最喜欢的格式）：
$ tail log/rails_2011-05-10.log
Started GET "/????_settings/19/edit" for 127.0.0.1 at ...
13:42:11 INFO: Processing by ????SettingsController ...
13:42:11 INFO: Parameters: {"id"=>"19"}
13:42:12 DEBUG: ????Setting Load (0.0ms) SELECT "d ...
13:42:12 INFO: Completed 200 OK in 750ms
我的环境：
- 操作系统：在 XP 中运行的 cygwin
- ruby 1.8.7 (2011-02-18 补丁级别 334) [i386-mingw32]
- 导轨：3.0.5
- 宝石：1.6.0
有任何问题请告诉我~ :-)
参考：https ://stackoverflow.com/a/20154414/445908
和rails6 log4r tagged_logging.rb:22:in `call': 参数数量错误