类路径中的远程jar [英] remote jars in the classpath

问题描述

很抱歉，也许这个问题太傻或者已经回答了，但是我找不到它。

我想知道是否有一些已知的Java类-loader，它能够接受类路径中的远程文件，即CLASSPATH =http：//somewhere.net/library.jar：...等条目。

<请注意，我不是在讨论applet或Java Web Start。想想可以使用不同后端的应用程序（例如，MySQL，Oracle），我想根据用户的后端首选项在shell脚本中准备类路径，并让类加载器下载所需的来自分发服务器的jar（本例中为jdbc驱动程序）。我也不是在谈论Maven（用户只是得到二进制分发，我不想强​​迫他们从源代码构建他们需要的东西）。

解决方案

SystemClassLoader 是 URLClassLoader 。您可以尝试，我留给您：

 方法方法= URLClassLoader.class.getDeclaredMethod（addURL，new Class [ ] {URL.class}）; 
 method.setAccessible（true）; 
 method.invoke（ClassLoader.getSystemClassLoader（），new Object [] {new URL（http://somewhere.net/library.jar）}）; 
 Class.forName（your.remote.ClassName）; 
  

请告诉我:)）

Sorry, maybe this question is too silly or already answered, but I couldn't find it out.

I'm wondering if there is some known Java class-loader that is able to accept remote files in the classpath, i.e., entries like CLASSPATH="http://somewhere.net/library.jar:...".

Note that I am not talking about applets or Java Web Start. Think of an application that can use different back-ends (e.g., MySQL, Oracle), I'd like to prepare the classpath in a shell script, based on the user's back-end preference and have the class-loader to download the needed jar (the jdbc driver in this example) from a distribution server. I'm not talking about Maven either (the user just gets the binary distribution, I don't want to force them to build what they need from the sources).

解决方案

The SystemClassLoader is a URLClassLoader. You could try, I leave it to you:

Method method = URLClassLoader.class.getDeclaredMethod("addURL", new Class[]{URL.class});
method.setAccessible(true);
method.invoke(ClassLoader.getSystemClassLoader(), new Object[]{new URL("http://somewhere.net/library.jar")});  
Class.forName("your.remote.ClassName");

Let me know :)

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