Decompile the jar package / class file / modify the jar package using the decompile plug-in of idea

Decompile The plugin is introduced

install IDEA after , Generally, it comes with decompiler plug-ins , Java Bytecode Decompiler
If not, you can install it yourself

1. First find the plug-in jar package , stay IDEA Installation directory plugins Under the folder

For example, my catalog is :

E:\IDEA\plugins\java-decompiler\lib\java-decompiler.jar

2. function java command , Specify the jar Package directory and what you want to decompile jar The package directory also generates decompiled jar The package directory

The order is as follows :

java -cp “E:\IDEA\plugins\java-decompiler\lib\java-decompiler.jar” \ 
org.jetbrains.java.decompiler.main.decompiler.ConsoleDecompiler -dgs=true \ 
D:\maven\respository\xxx\xxx-0.0.1-SNAPSHOT.jar D:\src

E:\IDEA\plugins\java-decompiler\lib\java-decompiler.jar It's my plug-in directory
D:\maven\respository\xxx\xxx-1.5.0-SNAPSHOT.jar I want to decompile jar package
D:\src I want to generate decompiled jar The package directory

When jre Version below class An error will be reported when the version of the file

error message :

Error: A JNI error has occurred, please check your installation and try again
Exception in thread “main” java.lang.UnsupportedClassVersionError: org/jetbrains/java/decompiler/main/decompiler/ConsoleDecompiler has been compiled by a more recent version of the Java Runtime (class file version 55.0), this version of the Java Runtime only recognizes class file versions up to 52.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:763)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:467)
at java.net.URLClassLoader.access$100(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:368)
at java.net.URLClassLoader$1.run(URLClassLoader.java:362)atjava.security.AccessController.doPrivileged(NativeMethod)atjava.net.URLClassLoader.findClass(URLClassLoader.java:361)atjava.lang.ClassLoader.loadClass(ClassLoader.java:424)atsun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:335)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:495)

class Document version follows jdk The version correspondence is as follows

49 = Java 5
50 = Java 6
51 = Java 7
52 = Java 8
53 = Java 9
54 = Java 10
55 = Java 11
56 = Java 12
57 = Java 13
58 = Java 14
59 = Java 15
60 = Java 16

We can specify the higher version installed by ourselves JDK To run the , For example, here I use my own installation JDK11 To run the

E:\JDK\jdk11.0.10\bin\java -cp \ 
“E:\IDEA\plugins\java-decompiler\lib\java-decompiler.jar” \ 
org.jetbrains.java.decompiler.main.decompiler.ConsoleDecompiler -dgs=true \ 
E:\Java_develop\Maven\repository\com\xxx\xxx\0.0.1-SNAPSHOT\xxx.jar D:\src\

3. You can decompress it directly jar package

jar A package is actually a compressed package file , Like the ones that we see all the time zip/rar
You can decompress it directly with a compression tool , Also can put the xxx.jar Change the suffix to xxx.zip After decompression
Decompress and import directly IDEA modify , After modification, compile and package

4. hit jar Package order

hit jar Package order , Match all files of the current directory file *.class The file hits jar In bag

jar cvf xxx.jar ./

Appoint manifest Package files

jar cvfm xxx.jar MANIFEST.MF *.class