2.3 KiB
- It is recommended to use the [OGNL] (https://arthas.aliyun.com/doc/arthas-tutorials.html?language=en&id=command-ognl) command, which will be more flexible.
Check the static fields of classes conveniently, the usage is getstatic class_name field_name.
getstatic demo.MathGame random{{execute T2}}
$ getstatic demo.MathGame random
field: random
@Random[
serialVersionUID=@Long[3905348978240129619],
seed=@AtomicLong[120955813885284],
multiplier=@Long[25214903917],
addend=@Long[11],
mask=@Long[281474976710655],
DOUBLE_UNIT=@Double[1.1102230246251565E-16],
BadBound=@String[bound must be positive],
BadRange=@String[bound must be greater than origin],
BadSize=@String[size must be non-negative],
seedUniquifier=@AtomicLong[-3282039941672302964],
nextNextGaussian=@Double[0.0],
haveNextNextGaussian=@Boolean[false],
serialPersistentFields=@ObjectStreamField[][isEmpty=false;size=3],
unsafe=@Unsafe[sun.misc.Unsafe@2eaa1027],
seedOffset=@Long[24],
]
- Specify classLoader
Note that the hashcode changes, you need to check the current ClassLoader information first, and extract the hashcode corresponding to the ClassLoader using sc -d <ClassName>.
if you use-c, you have to manually type hashcode by -c <hashcode>.
$ getstatic -c 3d4eac69 demo.MathGame random
For classloader with only one instance, it can be specified by --classLoaderClass using class name, which is more convenient to use.
getstatic --classLoaderClass demo.MathGame random{{execute T2}}
- PS: Here the classLoaderClass in java 8 is sun.misc.Launcher$AppClassLoader, while in java 11 it's jdk.internal.loader.ClassLoaders$AppClassLoader. Currently katacoda using java 8.
The value of --classloaderclass is the class name of classloader. It can only work when it matches a unique classloader instance. The purpose is to facilitate the input of general commands. However, -c <hashcode> is dynamic.
Tip: if the static field is a complex class, you can even use OGNL to traverse, filter and access the inner properties of this class.