如何设置log4j属性文件? [英] How to set log4j property file?

问题描述

我有一个使用log4j的Eclipse Java项目.我无法设置要通过文件路径访问的log4j配置文件.我必须在jar中导出并运行该项目.

I have an Eclipse Java Project which uses log4j. I can't set the log4j configuration file to be accessed by file path. I have to export and run the project in a jar.

这是我的尝试方式:

public class Wita {
  static Logger logger;
  public static void main(String[] args) {
    System.setProperty("log4j.configuration", new File("").getCanonicalPath()+File.separatorChar+"resources"+File.separatorChar+"log4j.xml" );
    // System.out.println( System.getProperty("log4j.configuration") );
    logger = Logger.getLogger(Wita.class.getName());
  }
}

系统输出将打印出 C:\ Users \ roncsak \ eclipse_workspace \ WITA \ resources \ log4j.xml . WITA 是项目的基本文件夹.但是，使用 -Dlog4j.debug 参数运行项目时，也会返回以下内容:

System out prints the C:\Users\roncsak\eclipse_workspace\WITA\resources\log4j.xml which is good. WITA is the base folder of the project. But running the project with -Dlog4j.debug argument the following returns also:

log4j: Trying to find [C:\Users\roncsak\eclipse_workspace\WITA\resources\log4j.xml] using context classloader sun.misc.Launcher$AppClassLoader@18e3e60.
log4j: Trying to find [C:\Users\roncsak\eclipse_workspace\WITA\resources\log4j.xml] using sun.misc.Launcher$AppClassLoader@18e3e60 class loader.
log4j: Trying to find [C:\Users\roncsak\eclipse_workspace\WITA\resources\log4j.xml] using ClassLoader.getSystemResource().
log4j: Could not find resource: [C:\Users\roncsak\eclipse_workspace\WITA\resources\log4j.xml].

我想随着时间的推移更改log4j.xml，而不构建另一个jar文件.我该怎么办?

I would like to change the log4j.xml over time, without building another jar file. How can I do that?

推荐答案

来自

• 将资源字符串变量设置为 log4j.configuration系统属性.指定的首选方式 默认的初始化文件是通过log4j.configuration系统 财产.如果系统属性log4j.configuration不是 定义，然后将字符串变量资源设置为其默认值 "log4j.properties".
• 尝试将资源变量转换为URL.
• 如果无法将资源变量转换为URL，例如Due 到MalformedURLException，然后从 通过调用类路径 org.apache.log4j.helpers.Loader.getResource(资源，Logger.class) 它返回一个URL.请注意，字符串"log4j.properties" 构成格式错误的URL.请参见Loader.getResource(java.lang.String) 有关搜索到的位置的列表.

• Set the resource string variable to the value of the log4j.configuration system property. The preferred way to specify the default initialization file is through the log4j.configuration system property. In case the system property log4j.configuration is not defined, then set the string variable resource to its default value "log4j.properties".
• Attempt to convert the resource variable to a URL.
• If the resource variable cannot be converted to a URL, for example due to a MalformedURLException, then search for the resource from the classpath by calling org.apache.log4j.helpers.Loader.getResource(resource, Logger.class) which returns a URL. Note that the string "log4j.properties" constitutes a malformed URL. See Loader.getResource(java.lang.String) for the list of searched locations.

因此，您需要将file:放在log4j.configuration属性值之前，以便可以将其视为URL.

So you need to prepend file: to log4j.configuration property value in order that it can be treated as URL.

请参见 https://stackoverflow.com/a/7927278/603516 .

更好的代码:

    System.setProperty("log4j.configuration", new File("resources", "log4j.xml").toURL());

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