java class file及反汇编后的jvm指令

工程目录结构如下：

HStudy

--src

--jvm

--init

--classes

--jvm

--init

源码如下：

package jvm.init;
public class Example5 {
    public static void main(String[] args) {
    	int a = 2;
    	int b = 3;
        if (args.length < 2) {
            System.out.println("Must enter any two args.");
            return;
        }
 
        System.out.println(args[0] + args[1]);
    }
}

以下是在命令行下的操作：

编译源码 E:\workspace_RIA\HStudy>javac -g -classpath classes -sourcepath src src\jvm\init\Example5.java -d classes

生成的class文件的16进制码如下：

00000000h: CA FE BA BE 00 00 00 31 00 30 0A 00 0A 00 1B 09 ; 漱壕...1.0......
00000010h: 00 1C 00 1D 08 00 1E 0A 00 1F 00 20 07 00 21 0A ; ........... ..!.
00000020h: 00 05 00 1B 0A 00 05 00 22 0A 00 05 00 23 07 00 ; ........"....#..
00000030h: 24 07 00 25 01 00 06 3C 69 6E 69 74 3E 01 00 03 ; $..%...<init>...
00000040h: 28 29 56 01 00 04 43 6F 64 65 01 00 0F 4C 69 6E ; ()V...Code...Lin
00000050h: 65 4E 75 6D 62 65 72 54 61 62 6C 65 01 00 12 4C ; eNumberTable...L
00000060h: 6F 63 61 6C 56 61 72 69 61 62 6C 65 54 61 62 6C ; ocalVariableTabl
00000070h: 65 01 00 04 74 68 69 73 01 00 13 4C 6A 76 6D 2F ; e...this...Ljvm/
00000080h: 69 6E 69 74 2F 45 78 61 6D 70 6C 65 35 3B 01 00 ; init/Example5;..
00000090h: 04 6D 61 69 6E 01 00 16 28 5B 4C 6A 61 76 61 2F ; .main...([Ljava/
000000a0h: 6C 61 6E 67 2F 53 74 72 69 6E 67 3B 29 56 01 00 ; lang/String;)V..
000000b0h: 04 61 72 67 73 01 00 13 5B 4C 6A 61 76 61 2F 6C ; .args...[Ljava/l
000000c0h: 61 6E 67 2F 53 74 72 69 6E 67 3B 01 00 01 61 01 ; ang/String;...a.
000000d0h: 00 01 49 01 00 01 62 01 00 0A 53 6F 75 72 63 65 ; ..I...b...Source
000000e0h: 46 69 6C 65 01 00 0D 45 78 61 6D 70 6C 65 35 2E ; File...Example5.
000000f0h: 6A 61 76 61 0C 00 0B 00 0C 07 00 26 0C 00 27 00 ; java.......&..'.
00000100h: 28 01 00 18 4D 75 73 74 20 65 6E 74 65 72 20 61 ; (...Must enter a
00000110h: 6E 79 20 74 77 6F 20 61 72 67 73 2E 07 00 29 0C ; ny two args...).
00000120h: 00 2A 00 2B 01 00 17 6A 61 76 61 2F 6C 61 6E 67 ; .*.+...java/lang
00000130h: 2F 53 74 72 69 6E 67 42 75 69 6C 64 65 72 0C 00 ; /StringBuilder..
00000140h: 2C 00 2D 0C 00 2E 00 2F 01 00 11 6A 76 6D 2F 69 ; ,.-..../...jvm/i
00000150h: 6E 69 74 2F 45 78 61 6D 70 6C 65 35 01 00 10 6A ; nit/Example5...j
00000160h: 61 76 61 2F 6C 61 6E 67 2F 4F 62 6A 65 63 74 01 ; ava/lang/Object.
00000170h: 00 10 6A 61 76 61 2F 6C 61 6E 67 2F 53 79 73 74 ; ..java/lang/Syst
00000180h: 65 6D 01 00 03 6F 75 74 01 00 15 4C 6A 61 76 61 ; em...out...Ljava
00000190h: 2F 69 6F 2F 50 72 69 6E 74 53 74 72 65 61 6D 3B ; /io/PrintStream;
000001a0h: 01 00 13 6A 61 76 61 2F 69 6F 2F 50 72 69 6E 74 ; ...java/io/Print
000001b0h: 53 74 72 65 61 6D 01 00 07 70 72 69 6E 74 6C 6E ; Stream...println
000001c0h: 01 00 15 28 4C 6A 61 76 61 2F 6C 61 6E 67 2F 53 ; ...(Ljava/lang/S
000001d0h: 74 72 69 6E 67 3B 29 56 01 00 06 61 70 70 65 6E ; tring;)V...appen
000001e0h: 64 01 00 2D 28 4C 6A 61 76 61 2F 6C 61 6E 67 2F ; d..-(Ljava/lang/
000001f0h: 53 74 72 69 6E 67 3B 29 4C 6A 61 76 61 2F 6C 61 ; String;)Ljava/la
00000200h: 6E 67 2F 53 74 72 69 6E 67 42 75 69 6C 64 65 72 ; ng/StringBuilder
00000210h: 3B 01 00 08 74 6F 53 74 72 69 6E 67 01 00 14 28 ; ;...toString...(
00000220h: 29 4C 6A 61 76 61 2F 6C 61 6E 67 2F 53 74 72 69 ; )Ljava/lang/Stri
00000230h: 6E 67 3B 00 21 00 09 00 0A 00 00 00 00 00 02 00 ; ng;.!...........
00000240h: 01 00 0B 00 0C 00 01 00 0D 00 00 00 2F 00 01 00 ; ............/...
00000250h: 01 00 00 00 05 2A B7 00 01 B1 00 00 00 02 00 0E ; .....*?.?.....
00000260h: 00 00 00 06 00 01 00 00 00 03 00 0F 00 00 00 0C ; ................
00000270h: 00 01 00 00 00 05 00 10 00 11 00 00 00 09 00 12 ; ................
00000280h: 00 13 00 01 00 0D 00 00 00 86 00 04 00 03 00 00 ; .........?.....
00000290h: 00 30 05 3C 06 3D 2A BE 05 A2 00 0C B2 00 02 12 ; .0.<.=*??.?..
000002a0h: 03 B6 00 04 B1 B2 00 02 BB 00 05 59 B7 00 06 2A ; .?.辈..?.Y?.*
000002b0h: 03 32 B6 00 07 2A 04 32 B6 00 07 B6 00 08 B6 00 ; .2?.*.2?.?.?
000002c0h: 04 B1 00 00 00 02 00 0E 00 00 00 1E 00 07 00 00 ; .?.............
000002d0h: 00 05 00 02 00 06 00 04 00 07 00 0A 00 08 00 12 ; ................
000002e0h: 00 09 00 13 00 0C 00 2F 00 0D 00 0F 00 00 00 20 ; ......./....... 
000002f0h: 00 03 00 00 00 30 00 14 00 15 00 00 00 02 00 2E ; .....0..........
00000300h: 00 16 00 17 00 01 00 04 00 2C 00 18 00 17 00 02 ; .........,......
00000310h: 00 01 00 19 00 00 00 02 00 1A                   ; ..........

反编译 E:\workspace_RIA\HStudy>javap -c -classpath classes jvm.init.Example5 -verbose

注意：不要在类后面加.class后缀，这儿与javac恰好相反

E:\workspace_RIA\HStudy>javac -g -classpath classes -sourcepath src src\jvm\init
\Example5.java -d classes
E:\workspace_RIA\HStudy>javap -c -classpath classes jvm.init.Example5 -verbose
Compiled from "Example5.java"
public class jvm.init.Example5 extends java.lang.Object
  SourceFile: "Example5.java"
  minor version: 0
  major version: 49
  Constant pool:
const #1 = Method       #10.#27;        //  java/lang/Object."<init>":()V
const #2 = Field        #28.#29;        //  java/lang/System.out:Ljava/io/PrintS
tream;
const #3 = String       #30;    //  Must enter any two args.
const #4 = Method       #31.#32;        //  java/io/PrintStream.println:(Ljava/l
ang/String;)V
const #5 = class        #33;    //  java/lang/StringBuilder
const #6 = Method       #5.#27; //  java/lang/StringBuilder."<init>":()V
const #7 = Method       #5.#34; //  java/lang/StringBuilder.append:(Ljava/lang/S
tring;)Ljava/lang/StringBuilder;
const #8 = Method       #5.#35; //  java/lang/StringBuilder.toString:()Ljava/lan
g/String;
const #9 = class        #36;    //  jvm/init/Example5
const #10 = class       #37;    //  java/lang/Object
const #11 = Asciz       <init>;
const #12 = Asciz       ()V;
const #13 = Asciz       Code;
const #14 = Asciz       LineNumberTable;
const #15 = Asciz       LocalVariableTable;
const #16 = Asciz       this;
const #17 = Asciz       Ljvm/init/Example5;;
const #18 = Asciz       main;
const #19 = Asciz       ([Ljava/lang/String;)V;
const #20 = Asciz       args;
const #21 = Asciz       [Ljava/lang/String;;
const #22 = Asciz       a;
const #23 = Asciz       I;
const #24 = Asciz       b;
const #25 = Asciz       SourceFile;
const #26 = Asciz       Example5.java;
const #27 = NameAndType #11:#12;//  "<init>":()V
const #28 = class       #38;    //  java/lang/System
const #29 = NameAndType #39:#40;//  out:Ljava/io/PrintStream;
const #30 = Asciz       Must enter any two args.;
const #31 = class       #41;    //  java/io/PrintStream
const #32 = NameAndType #42:#43;//  println:(Ljava/lang/String;)V
const #33 = Asciz       java/lang/StringBuilder;
const #34 = NameAndType #44:#45;//  append:(Ljava/lang/String;)Ljava/lang/String
Builder;
const #35 = NameAndType #46:#47;//  toString:()Ljava/lang/String;
const #36 = Asciz       jvm/init/Example5;
const #37 = Asciz       java/lang/Object;
const #38 = Asciz       java/lang/System;
const #39 = Asciz       out;
const #40 = Asciz       Ljava/io/PrintStream;;
const #41 = Asciz       java/io/PrintStream;
const #42 = Asciz       println;
const #43 = Asciz       (Ljava/lang/String;)V;
const #44 = Asciz       append;
const #45 = Asciz       (Ljava/lang/String;)Ljava/lang/StringBuilder;;
const #46 = Asciz       toString;
const #47 = Asciz       ()Ljava/lang/String;;
{
public jvm.init.Example5();
  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       Ljvm/init/Example5;
public static void main(java.lang.String[]);
  Code:
   Stack=4, Locals=3, Args_size=1
   0:   iconst_2
   1:   istore_1
   2:   iconst_3
   3:   istore_2
   4:   aload_0
   5:   arraylength
   6:   iconst_2
   7:   if_icmpge       19
   10:  getstatic       #2; //Field java/lang/System.out:Ljava/io/PrintStream;
   13:  ldc     #3; //String Must enter any two args.
   15:  invokevirtual   #4; //Method java/io/PrintStream.println:(Ljava/lang/Str
ing;)V
   18:  return
   19:  getstatic       #2; //Field java/lang/System.out:Ljava/io/PrintStream;
   22:  new     #5; //class java/lang/StringBuilder
   25:  dup
   26:  invokespecial   #6; //Method java/lang/StringBuilder."<init>":()V
   29:  aload_0
   30:  iconst_0
   31:  aaload
   32:  invokevirtual   #7; //Method java/lang/StringBuilder.append:(Ljava/lang/
String;)Ljava/lang/StringBuilder;
   35:  aload_0
   36:  iconst_1
   37:  aaload
   38:  invokevirtual   #7; //Method java/lang/StringBuilder.append:(Ljava/lang/
String;)Ljava/lang/StringBuilder;
   41:  invokevirtual   #8; //Method java/lang/StringBuilder.toString:()Ljava/la
ng/String;
   44:  invokevirtual   #4; //Method java/io/PrintStream.println:(Ljava/lang/Str
ing;)V
   47:  return
  LineNumberTable:
   line 5: 0
   line 6: 2
   line 7: 4
   line 8: 10
   line 9: 18
   line 12: 19
   line 13: 47
  LocalVariableTable:
   Start  Length  Slot  Name   Signature
   0      48      0    args       [Ljava/lang/String;
   2      46      1    a       I
   4      44      2    b       I
}

评论

1 楼 daly1987 2011-12-19  

不错啊，学习了