classloader

查看ClassLoader继承树，加载URL信息，类加载信息。

命令选项

命令选项	描述
-a, --all	列出所有被ClassLoader加载的类，请谨慎使用
-c, --classloader <hash>	指定ClassLoader的哈希值
--classLoaderClass <name>	指定ClassLoader的类名
-i, --include-reflection-classloader	包含sun.reflect.DelegatingClassLoader
-l, --list-classloader	列出ClassLoader实例信息
--load <className>	加载给定的类，必须指定ClassLoader，即-c
-r, --resource <name>	查找给定名字的资源，必须指定ClassLoader，即-c
-t, --tree	展示ClassLoader树
-u, --url-stat	展示ClassLoader URL统计信息
-h, --help	帮助

示例

# 查看ClassLoader实例及加载类信息
[arthas@14064]$ classloader
name                                                  numberOfInstances  loadedCountTotal
BootstrapClassLoader                                  1                  3508
java.net.URLClassLoader                               1                  2020
com.taobao.arthas.agent.ArthasClassloader             1                  1395
jdk.internal.loader.ClassLoaders$PlatformClassLoader  1                  92
jdk.internal.reflect.DelegatingClassLoader            15                 15
jdk.internal.loader.ClassLoaders$AppClassLoader       1                  4
Affect(row-cnt:6) cost in 2 ms.

# 查看ClassLoader加载类、hash、父ClassLoader信息
[arthas@14064]$ classloader -l
name                                                           loadedCount  hash      parent
BootstrapClassLoader                                           3508         null      null
com.taobao.arthas.agent.ArthasClassloader@435181e6             1393         435181e6  jdk.internal.loader.ClassLoaders$PlatformClassLoader@782458af
java.net.URLClassLoader@22a71081                               2020         22a71081  jdk.internal.loader.ClassLoaders$AppClassLoader@2328c243
jdk.internal.loader.ClassLoaders$AppClassLoader@2328c243       4            2328c243  jdk.internal.loader.ClassLoaders$PlatformClassLoader@782458af
jdk.internal.loader.ClassLoaders$PlatformClassLoader@782458af  92           782458af  null
Affect(row-cnt:5) cost in 2 ms.

# 查看ClassLoader树
[arthas@14064]$ classloader -t
+-BootstrapClassLoader
+-jdk.internal.loader.ClassLoaders$PlatformClassLoader@782458af
  +-com.taobao.arthas.agent.ArthasClassloader@435181e6
  +-jdk.internal.loader.ClassLoaders$AppClassLoader@2328c243
    +-java.net.URLClassLoader@22a71081
Affect(row-cnt:5) cost in 3 ms.

# 查找指定名字的资源 必须是全路径且必须指定ClassLoader
[arthas@14064]$ classloader -c 435181e6 -r META-INF/MANIFEST.MF
jar:file:/C:/Users/A/.arthas/lib/3.6.7/arthas/arthas-core.jar!/META-INF/MANIFEST.MF
# 查找指定的Class
[arthas@14064]$ classloader -c 435181e6 -r java/lang/String.class
jrt:/java.base/java/lang/String.class

# 加载class
[arthas@14064]$ classloader -c 435181e6 --load com.alibaba.arthas.deps.ZZZ
load class success.
class-info        com.alibaba.arthas.deps.ZZZ
code-source       /C:/Users/A/.arthas/lib/3.6.7/arthas/arthas-core.jar
name              com.alibaba.arthas.deps.ZZZ
isInterface       false
isAnnotation      false
isEnum            false
isAnonymousClass  false
isArray           false
isLocalClass      false
isMemberClass     false
isPrimitive       false
isSynthetic       false
simple-name       ZZZ
modifier          public
annotation
interfaces
super-class       +-java.lang.Object
class-loader      +-com.taobao.arthas.agent.ArthasClassloader@435181e6
                 +-jdk.internal.loader.ClassLoaders$PlatformClassLoader@782458af
classLoaderHash   435181e6
# 加载已加载的类
[arthas@14064]$ classloader -c 435181e6 --load java.lang.String
load class success.
class-info        java.lang.String
code-source
name              java.lang.String
isInterface       false
isAnnotation      false
isEnum            false
isAnonymousClass  false
isArray           false
isLocalClass      false
isMemberClass     false
isPrimitive       false
isSynthetic       false
simple-name       String
modifier          final,public
annotation
interfaces        java.io.Serializable,java.lang.Comparable,java.lang.CharSequence,java.lang.constant.Constable,java.lang.constant.ConstantDesc
super-class       +-java.lang.Object
class-loader
classLoaderHash   null