从JAR目录中读取属性文件 [英] Reading properties file from JAR directory

问题描述

我正在创建一个可执行的JAR，它将在运行时从一个文件中读取一组属性。目录结构类似于：

I’m creating an executable JAR that will read in a set of properties at runtime from a file. The directory structure will be something like:

/some/dirs/executable.jar
/some/dirs/executable.properties

有没有办法在executable.jar文件中设置属性加载器类来加载jar所在目录中的属性，而不是对目录进行硬编码。

Is there a way of setting the property loader class in the executable.jar file to load the properties from the directory that the jar is in, rather than hard-coding the directory.

我不想把属性放在jar本身，因为属性文件需要配置。

I don't want to put the properties in the jar itself as the properties file needs to be configurable.

推荐答案

为什么不将属性文件作为参数传递给main方法？这样你可以按如下方式加载属性：

Why not just pass the properties file as an argument to your main method? That way you can load the properties as follows:

public static void main(String[] args) throws IOException {
  Properties props = new Properties();
  props.load(new BufferedReader(new FileReader(args[0])));
  System.setProperties(props);
}

另一种选择：如果你想得到jar文件的当前目录你我需要做一些讨厌的事情：

The alternative: If you want to get the current directory of your jar file you need to do something nasty like:

CodeSource codeSource = MyClass.class.getProtectionDomain().getCodeSource();
File jarFile = new File(codeSource.getLocation().toURI().getPath());
File jarDir = jarFile.getParentFile();

if (jarDir != null && jarDir.isDirectory()) {
  File propFile = new File(jarDir, "myFile.properties");
}

...其中 MyClass 是jar文件中的一个类。这不是我推荐的东西 - 如果你的应用程序在不同jar文件（不同目录中的每个jar）的类路径上有多个 MyClass 实例怎么办？即你永远不能保证从你认为的罐子里加载 MyClass 。

... where MyClass is a class from within your jar file. It's not something I'd recommend though - What if your app has multiple MyClass instances on the classpath in different jar files (each jar in a different directory)? i.e. You can never really guarantee that MyClass was loaded from the jar you think it was.

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