JDK1.9及以后的版本中ExtClassLoader变成PlatFromClassLoader？

Question

JDK1.9及以后的版本中ExtClassLoader变成PlatFromClassLoader,目的就是觉得将*.jar直接放到Ext目录下执行不安全？所以1.9直接废除了这种做法？提供了平台类加载器，为了和系统类加载器与应用类加载器之间保持设计平衡？

Answer 1

翔仔 2018-12-27 00:24:24

同学好，

1.9之后ExtClassLoader更名为PlatFromClassLoader，加载lib/modules目录下的class。这个我理解只是一种规范上的变化，即要求所有Java SE平台上的类都需要保证对PlatFromClassLoader可见，应该是另外一种类型的划分。

The extension class loader has been renamed; it is now the platform class loader. All classes in the Java SE Platform are guaranteed to be visible through the platform class loader. In addition, the classes in modules that are standardized under the Java Community Process but not part of the Java SE Platform are guaranteed to be visible through the platform class loader.

Just because a class is visible through the platform class loader does not mean the class is actually defined by the platform class loader. Some classes in the Java SE Platform are defined by the platform class loader while others are defined by the bootstrap class loader. Applications should not depend on which class loader defines which platform class.