java.lang.IllegalAccessError：尝试从类Entity访问字段ConcreteEntity.instance [英] java.lang.IllegalAccessError: tried to access field ConcreteEntity.instance from class Entity

问题描述

java.lang.IllegalAccessError：尝试从类实体访问字段ConcreteEntity.instance

java.lang.IllegalAccessError: tried to access field ConcreteEntity.instance from class Entity

Ok所以这里是交易。我正在尝试访问 ConcreteEntity.instance 这是一个具有默认访问类型的字段，该字段存在于默认的 ClassLoader 中，并且 Entity.getInstance 是一个存在于子 ClassLoader 中的方法。

Ok so here is the deal. I am trying to access ConcreteEntity.instance which is a field with the access type default that exists inside the default ClassLoader and the Entity.getInstance is a method that exist in a child ClassLoader.

现在请记住，它们都在同一个包中，但是抛出了 IllegalAccessError 。是否有一个解决这个问题的方法，不涉及我实际在同一个 ClassLoader 中加载Entity类为 ConcreteEntity ？

Now keep in mind they're both in the same package, however an IllegalAccessError is being thrown. Is there a solution to this problem that doesn't involve me actually loading the Entity class inside the same ClassLoader as ConcreteEntity?

0 new #14 <Entity>
 3 dup
 4 aload_0
 5 invokevirtual #18 <Adapter.getInstance>
 8 checkcast #20 <sl>
11 getfield #24 <sl.d>
14 invokespecial #25 <Entity.<init>>
17 areturn

通过jclasslib at检索的字节码是生成的异常编译后。

The bytecode retrieved via jclasslib at were the exception is generated "After being compiled".

感谢Gamb清理帖子。

推荐答案

请参阅我的回答 一个类似的问题，除了你的情况很明显你正在处理多个类加载器：

See my answer to a similar question, except in your case it is clear that you are dealing with multiple classloaders:

jvm认为从不同的类加载器加载的类在不同的运行时包中，即使它们具有相同的包名。引自 jvm spceification ，部分5.3：

The jvm considers classes loaded from different classloaders to be in different "runtime packages", even if they have the same package name. Quoting from the jvm spceification, section 5.3:

在运行时，类或接口不仅由其名称决定，而是由一对确定：它的完全限定名称和它定义的类加载器。每个这样的类或接口都属于一个运行时包。类或接口的运行时包由包名称和类或接口的类加载器确定。

At run time, a class or interface is determined not by its name alone, but by a pair: its fully qualified name and its defining class loader. Each such class or interface belongs to a single runtime package. The runtime package of a class or interface is determined by the package name and defining class loader of the class or interface.

在部分中5.4.4：

当且仅当以下任何条件为真时，类或接口D才能访问字段或方法R. ：

A field or method R is accessible to a class or interface D if and only if any of the following conditions is true:

...

R受保护或包私有（即既不公开也不保护也不私有），并由与相同的运行时包中的类声明。

R is either protected or package private (that is, neither public nor protected nor private), and is declared by a class in the same runtime package as D.

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