log4cxx-是否可以使用来自配置文件的自定义参数来配置自定义附加程序? [英] log4cxx -- is it possible to configure a custom appender with custom arguments from a config file?

问题描述

我需要在log4cxx中编写一个自定义附加程序. 此答案描述了如何执行此操作.在Java中，在log4j中，自定义附加程序可以设计自定义参数.我添加了一个属性以及一个getter和setter:

I need to write a custom appender in log4cxx. This answer describes how to do it. In Java, in log4j, it is possible for a custom appender to devise custom parameters. I add a property and a getter and setter:

 private int myParameter = 0;
 public void setMyParameter(int p) { myParameter = p; }
 public int  getMyParameter() { return myParameter; }

然后我可以在配置文件中使用myParameter，并且框架以某种方式知道如何使用它配置我的附加程序.

Then I can use myParameter in configuration file, and the framework somehow knows how to configure my appender with it.

问题:log4cxx是否具有类似的功能?对我来说，只要获得具有属性的地图map<string, string>就足够了.

Question: does log4cxx have a similar capability? For me it is enough if I get a map map<string, string> with properties.

推荐答案

好，我自己想出了答案.您需要重写成员函数setOption.它将被调用多次:每个读取选项一次.然后，您将覆盖函数activateOptions并在处理完所有选项后调用它.它可以用作触发器，以使用读取的参数初始化附加器.

Ok, figured out the answer myself. You need to override member function setOption. It will get called a number of times: once per each read option. You then override function activateOptions and its get called after all options have been processed. It can be used as a trigger to initialize the appender with the read parameters.

不如映射到getter/setter那样方便，但是它可以完成工作:

Not as convenient as mapping to getters/setters, but it gets the job done:

class CustomAppender : public AppenderSkeleton
{
  int _myParameter = 0;
  void initialize(int myParameter);
  // ...

public:
  void setOption(LogString const& option, LogString const& value) override
  {
    if (option == "MyParameter") try
    {
      _myParameter = boost::lexical_cast<int>(value);
    }
    catch (boost::bad_lexical_cast const&) {
      // go with default
    }
  }

  void activateOptions(helpers::Pool &) override
  {
    initialize(_myParameter);
  }
};

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