查看字节码

1.安装插件
ASM Bytecode outline 与hexview

2.查看字节码
源码

package com.asm;

public class HelloWorld{
    public static void main(){
        System.out.println("HelloWorld!-----0");
    }
}

当前面板下有三项内容：
• Bytecode 表示对应的class字节码文件
• ASMified 表示利用ASM框架生成字节码对应的代码
• Groovified 对应的是class字节码指令

1. Hexview查看
   仅仅是以16进制显示.class文件
   这个是真正的字节码，而asm插件中的字节码，是以人类可读的方式处理过。类似javap
   在*.java类里，右键–>HexView
   
   通过javap查看字节码, 编译后的类不包含package和import信息

lichunmeideMBP:asm lichunmei$ javap -verbose HelloWorld.class
Classfile /Users/lichunmei/Documents/workspace/study/test/target/classes/com/asm/HelloWorld.class
  Last modified Jul 20, 2021; size 483 bytes
  MD5 checksum 1b366777e21b97772d6e0a892cc8bc05
  Compiled from "HelloWorld.java"
public class com.asm.HelloWorld
  minor version: 0
  major version: 52
  flags: ACC_PUBLIC, ACC_SUPER
Constant pool:
   #1 = Methodref          #6.#17         // java/lang/Object."<init>":()V
   #2 = Fieldref           #18.#19        // java/lang/System.out:Ljava/io/PrintStream;
   #3 = String             #20            // HelloWorld!-----0
   #4 = Methodref          #21.#22        // java/io/PrintStream.println:(Ljava/lang/String;)V
   #5 = Class              #23            // com/asm/HelloWorld
   #6 = Class              #24            // java/lang/Object
   #7 = Utf8               <init>
   #8 = Utf8               ()V
   #9 = Utf8               Code
  #10 = Utf8               LineNumberTable
  #11 = Utf8               LocalVariableTable
  #12 = Utf8               this
  #13 = Utf8               Lcom/asm/HelloWorld;
  #14 = Utf8               main
  #15 = Utf8               SourceFile
  #16 = Utf8               HelloWorld.java
  #17 = NameAndType        #7:#8          // "<init>":()V
  #18 = Class              #25            // java/lang/System
  #19 = NameAndType        #26:#27        // out:Ljava/io/PrintStream;
  #20 = Utf8               HelloWorld!-----0
  #21 = Class              #28            // java/io/PrintStream
  #22 = NameAndType        #29:#30        // println:(Ljava/lang/String;)V
  #23 = Utf8               com/asm/HelloWorld
  #24 = Utf8               java/lang/Object
  #25 = Utf8               java/lang/System
  #26 = Utf8               out
  #27 = Utf8               Ljava/io/PrintStream;
  #28 = Utf8               java/io/PrintStream
  #29 = Utf8               println
  #30 = Utf8               (Ljava/lang/String;)V
{
  public com.asm.HelloWorld();
    descriptor: ()V
    flags: ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
         0: aload_0
         1: invokespecial #1                  // Method java/lang/Object."<init>":()V
         4: return
      LineNumberTable:
        line 3: 0
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
            0       5     0  this   Lcom/asm/HelloWorld;

  public static void main();
    descriptor: ()V
    flags: ACC_PUBLIC, ACC_STATIC
    Code:
      stack=2, locals=0, args_size=0
         0: getstatic     #2                  // Field java/lang/System.out:Ljava/io/PrintStream;
         3: ldc           #3                  // String HelloWorld!-----0
         5: invokevirtual #4                  // Method java/io/PrintStream.println:(Ljava/lang/String;)V
         8: return
      LineNumberTable:
        line 5: 0
        line 6: 8
}
SourceFile: "HelloWorld.java"