import{_ as l,o as i,c as u,a as s,b as a,w as t,e as n,d as o,r as p}from"./app.5024572d.js";const r={},d=s("h1",{id:"jad",tabindex:"-1"},[s("a",{class:"header-anchor",href:"#jad","aria-hidden":"true"},"#"),n(" jad")],-1),k={href:"https://arthas.aliyun.com/doc/arthas-tutorials?language=en&id=command-jad",target:"_blank",rel:"noopener noreferrer"},m=s("code",null,"jad",-1),v=n(" online tutorial"),h=s("div",{class:"custom-container tip"},[s("p",{class:"custom-container-title"},"TIP"),s("p",null,"Decompile the specified classes.")],-1),b=s("code",null,"jad",-1),g=n(" helps to decompile the byte code running in JVM to the source code to assist you to understand the logic behind better. If you need to download the bytecode of classes in a specific package directory in bulk, you can refer to the "),y=n("dump"),w=n(" tool for assistance."),f=o(`
Name | Specification |
---|---|
class-pattern | pattern for the class name |
[c:] | hashcode of the class loader that loads the class |
[classLoaderClass:] | The class name of the ClassLoader that executes the expression. |
[E] | turn on regex match while the default is wildcard match |
java.lang.String
$ jad java.lang.String
ClassLoader:
Location:
/*
* Decompiled with CFR.
*/
package java.lang;
import java.io.ObjectStreamField;
import java.io.Serializable;
...
public final class String
implements Serializable,
Comparable<String>,
CharSequence {
private final char[] value;
private int hash;
private static final long serialVersionUID = -6849794470754667710L;
private static final ObjectStreamField[] serialPersistentFields = new ObjectStreamField[0];
public static final Comparator<String> CASE_INSENSITIVE_ORDER = new CaseInsensitiveComparator();
...
public String(byte[] byArray, int n, int n2, Charset charset) {
/*460*/ if (charset == null) {
throw new NullPointerException("charset");
}
/*462*/ String.checkBounds(byArray, n, n2);
/*463*/ this.value = StringCoding.decode(charset, byArray, n, n2);
}
...
$ jad --source-only demo.MathGame
/*
* Decompiled with CFR 0_132.
*/
package demo;
import java.io.PrintStream;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.Random;
import java.util.concurrent.TimeUnit;
public class MathGame {
private static Random random = new Random();
public int illegalArgumentCount = 0;
...
$ jad demo.MathGame main
ClassLoader:
+-sun.misc.Launcher$AppClassLoader@232204a1
+-sun.misc.Launcher$ExtClassLoader@7f31245a
Location:
/private/tmp/math-game.jar
public static void main(String[] args) throws InterruptedException {
MathGame game = new MathGame();
while (true) {
/*16*/ game.run();
/*17*/ TimeUnit.SECONDS.sleep(1L);
}
}
--lineNumber
: Output source code contins line numbers, default value true$ jad demo.MathGame main --lineNumber false
ClassLoader:
+-sun.misc.Launcher$AppClassLoader@232204a1
+-sun.misc.Launcher$ExtClassLoader@7f31245a
Location:
/private/tmp/math-game.jar
public static void main(String[] args) throws InterruptedException {
MathGame game = new MathGame();
while (true) {
game.run();
TimeUnit.SECONDS.sleep(1L);
}
}
TIP
If the target class is loaded by multiple classloaders, jad
outputs the hashcode
of the corresponding classloaders, then you can re-run jad
and specify -c <hashcode>
to decompile the target class from the specified classloader.
$ jad org.apache.log4j.Logger
Found more than one class for: org.apache.log4j.Logger, Please use jad -c hashcode org.apache.log4j.Logger
HASHCODE CLASSLOADER
69dcaba4 +-monitor's ModuleClassLoader
6e51ad67 +-java.net.URLClassLoader@6e51ad67
+-sun.misc.Launcher$AppClassLoader@6951a712
+-sun.misc.Launcher$ExtClassLoader@6fafc4c2
2bdd9114 +-pandora-qos-service's ModuleClassLoader
4c0df5f8 +-pandora-framework's ModuleClassLoader
Affect(row-cnt:0) cost in 38 ms.
$ jad org.apache.log4j.Logger -c 69dcaba4
ClassLoader:
+-monitor's ModuleClassLoader
Location:
/Users/admin/app/log4j-1.2.14.jar
package org.apache.log4j;
import org.apache.log4j.spi.*;
public class Logger extends Category
{
private static final String FQCN;
protected Logger(String name)
{
super(name);
}
...
Affect(row-cnt:1) cost in 190 ms.
For classloader with only one instance, it can be specified by --classLoaderClass
using class name, which is more convenient to use.
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.
Decompile class with jad
need to dump corresponding classes into files. The default directory for dumpping classes is the directory of log file specified in logback.xml, we can use -d/--directory
to specify the directory for dummping class.
$ jad demo.MathGame -d /tmp/jad/dump