为什么`java.lang.SecurityException：禁止包名：java`是必需的？ [英] why `java.lang.SecurityException: Prohibited package name: java` is required?

问题描述

我创建了一个类String并将其放在包java中[实际上我想创建 java.lang 以查看classLoader加载哪个类

I created a class "String" and placed that in package "java" [ actually i wanted to create java.lang to see which class is loaded by classLoader as

一旦将类加载到JVM中，
相同的类（我重复，同一个类）
将不再被加载

Once a class is loaded into a JVM, the same class (I repeat, the same class) will not be loaded again

引自oreilly]。但是之后的事情，为什么运行这个类我得到了？
java.lang.SecurityException：禁止的包名： java

quoted from oreilly ] . But that thing later, why on running this class i am getting
java.lang.SecurityException: Prohibited package name: java

为什么安全性原因java不允许我在 java 包中有一个类？如果不进行此类检查，可以做什么？

For which security reason java is not allowing me to have a class in java package? What one could do if there will not be no such check?

推荐答案

用户代码从不允许将类放入其中一个标准Java包中。这样，用户代码就无法访问Java实现中的任何包私有类/方法/字段。其中一些包私有对象允许访问JVM内部。 （我特别想到 SharedSecrets 。）

User code is never allowed to put classes into one of the standard Java packages. That way, user code cannot access any package-private classes/methods/fields in the Java implementation. Some of those package-private objects allow access to JVM internals. (I'm thinking of SharedSecrets in particular.)

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