罐子里面的参考罐子 [英] Reference jars inside a jar

问题描述

我有一个jar，其内容如下所示：

I have a jar whose content looks as shown below,

以下是我的清单文件

Manifest-Version: 1.0
Ant-Version: Apache Ant 1.8.3
Created-By: 1.7.0_06-b24 (Oracle Corporation)
Main-Class: org.sai.com.DerbyDemo
Class-Path: derby.jar derbyclient.jar derbynet.jar derbytools.jar

<当我尝试运行jar时，它抛出了一个 ClassNotFoundExcception ，这意味着它没有引用外部jar中的jar。

When i try to run the jar, it has thrown a ClassNotFoundExcception meaning it isn't referencing the jars inside the outer jar.

在 Class-Path 属性中，如何引用jar（ derby.jar 等） ）在实际的jar里面？

In the Class-Path attribute, how can I reference jars (derby.jar, etc) inside the actual jar?

推荐答案

你需要一个自定义的类加载器，看看一个罐子。

You will need a custom class loader for this, have a look at One Jar.

One-JAR允许您将Java应用程序及其依赖项Jars打包到一个可执行的Jar文件中。

One-JAR lets you package a Java application together with its dependency Jars into a single executable Jar file.

它有一个ant任务，可以简化它的构建。

It has an ant task which can simplify the building of it as well.

参考（来自背景）

大多数开发人员合理地假设将依赖Jar文件放入他们自己的Jar文件中，并向META-INF添加Class-Path属性/ MANIFEST将发挥作用：

jarname.jar
| /META-INF
| |  MANIFEST.MF
| |    Main-Class: com.mydomain.mypackage.Main
| |    Class-Path: commons-logging.jar
| /com/mydomain/mypackage
| |  Main.class
| commons-logging.jar

不幸的是这是不起作用 。 Java Launcher $ AppClassLoader 不知道如何使用这种 Class-Path 。试图使用 jar：file：jarname.jar！/commons-logging.jar 也导致死胡同。只有将支持的Jar文件安装（即分散）到安装jarname.jar文件的目录中时，此方法才有效。

Unfortunately this is does not work. The Java Launcher$AppClassLoader does not know how to load classes from a Jar inside a Jar with this kind of Class-Path. Trying to use jar:file:jarname.jar!/commons-logging.jar also leads down a dead-end. This approach will only work if you install (i.e. scatter) the supporting Jar files into the directory where the jarname.jar file is installed.

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