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Snailclimb merged 1 commit into from
Mar 25, 2021
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Update 类加载器.md #1137

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6 changes: 3 additions & 3 deletions docs/java/jvm/类加载器.md
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Expand Up @@ -16,7 +16,7 @@

## 回顾一下类加载过程

类加载过程：**加载->连接->初始化**。连接过程又可分为三步:**验证->准备->解析**。
类加载过程：**加载->连接->初始化**。连接过程又可分为三步：**验证->准备->解析**。

![类加载过程](https://my-blog-to-use.oss-cn-beijing.aliyuncs.com/2019-6/类加载过程.png)

Expand All @@ -30,7 +30,7 @@ JVM 中内置了三个重要的 ClassLoader，除了 BootstrapClassLoader 其他

1. **BootstrapClassLoader(启动类加载器)** ：最顶层的加载类，由C++实现，负责加载 `%JAVA_HOME%/lib`目录下的jar包和类或者或被 `-Xbootclasspath`参数指定的路径中的所有类。
2. **ExtensionClassLoader(扩展类加载器)** ：主要负责加载目录 `%JRE_HOME%/lib/ext` 目录下的jar包和类，或被 `java.ext.dirs` 系统变量所指定的路径下的jar包。
3. **AppClassLoader(应用程序类加载器)** :面向我们用户的加载器，负责加载当前应用classpath下的所有jar包和类。
3. **AppClassLoader(应用程序类加载器)** ：面向我们用户的加载器，负责加载当前应用classpath下的所有jar包和类。

## 双亲委派模型

Expand Down Expand Up @@ -60,7 +60,7 @@ The Parent of ClassLodarDemo's ClassLoader is sun.misc.Launcher$ExtClassLoader@1
The GrandParent of ClassLodarDemo's ClassLoader is null
```

`AppClassLoader`的父类加载器为`ExtClassLoader`
`AppClassLoader`的父类加载器为`ExtClassLoader`，
`ExtClassLoader`的父类加载器为null，**null并不代表`ExtClassLoader`没有父类加载器，而是 `BootstrapClassLoader`** 。

其实这个双亲翻译的容易让别人误解，我们一般理解的双亲都是父母，这里的双亲更多地表达的是“父母这一辈”的人而已，并不是说真的有一个 Mother ClassLoader 和一个 Father ClassLoader 。另外，类加载器之间的“父子”关系也不是通过继承来体现的，是由“优先级”来决定。官方API文档对这部分的描述如下:
Expand Down