反编译

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public class Test1 {
    public static void main(String[] args) {
        int i=2;
        int j=3;
        int k=i+j;
    }
}

//javap -v
Last modified 2021年3月6日; size 476 bytes
  SHA-256 checksum 8e654caa67ddc0bcfb09a7b96a365eab397bb819078361cb1b83261628e1c49f
  Compiled from "Test1.java"
public class com.atguigu.spring5.test1.Test1
  minor version: 0
  major version: 52
  flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: #2                          // com/atguigu/spring5/test1/Test1
  super_class: #3                         // java/lang/Object
  interfaces: 0, fields: 0, methods: 2, attributes: 1
Constant pool:
   #1 = Methodref          #3.#21         // java/lang/Object."<init>":()V
   #2 = Class              #22            // com/atguigu/spring5/test1/Test1
   #3 = Class              #23            // java/lang/Object
   #4 = Utf8               <init>
   #5 = Utf8               ()V
   #6 = Utf8               Code
   #7 = Utf8               LineNumberTable
   #8 = Utf8               LocalVariableTable
   #9 = Utf8               this
  #10 = Utf8               Lcom/atguigu/spring5/test1/Test1;
  #11 = Utf8               main
  #12 = Utf8               ([Ljava/lang/String;)V
  #13 = Utf8               args
  #14 = Utf8               [Ljava/lang/String;
  #15 = Utf8               i
  #16 = Utf8               I
  #17 = Utf8               j
  #18 = Utf8               k
  #19 = Utf8               SourceFile
  #20 = Utf8               Test1.java
  #21 = NameAndType        #4:#5          // "<init>":()V
  #22 = Utf8               com/atguigu/spring5/test1/Test1
  #23 = Utf8               java/lang/Object
{
  public com.atguigu.spring5.test1.Test1();
    descriptor: ()V
    flags: (0x0001) 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/atguigu/spring5/test1/Test1;

  public static void main(java.lang.String[]);
    descriptor: ([Ljava/lang/String;)V
    flags: (0x0009) ACC_PUBLIC, ACC_STATIC
    Code:
      stack=2, locals=4, args_size=1
         0: iconst_2
         1: istore_1
         2: iconst_3
         3: istore_2
         4: iload_1
         5: iload_2
         6: iadd
         7: istore_3
         8: return
      LineNumberTable:
        line 5: 0
        line 6: 2
        line 7: 4
        line 8: 8
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
            0       9     0  args   [Ljava/lang/String;
            2       7     1     i   I
            4       5     2     j   I
            8       1     3     k   I
}
SourceFile: "Test1.java"

image-20200616095017354

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public class Hello {
    private static int a =1;
    public static void main(String[] args) {
        System.out.println(a);
    }
}
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  Last modified 2021年3月6日; size 617 bytes
  SHA-256 checksum 1291c5b272d5f382ff660f3c4781d8e4c15e309213158643e41f07641d479a58
  Compiled from "Hello.java"
public class com.atguigu.spring5.test1.Hello
  minor version: 0
  major version: 52
  flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: #5                          // com/atguigu/spring5/test1/Hello
  super_class: #6                         // java/lang/Object
  interfaces: 0, fields: 1, methods: 3, attributes: 1
Constant pool:
   #1 = Methodref          #6.#23         // java/lang/Object."<init>":()V
   #2 = Fieldref           #24.#25        // java/lang/System.out:Ljava/io/PrintStream;
   #3 = Fieldref           #5.#26         // com/atguigu/spring5/test1/Hello.a:I
   #4 = Methodref          #27.#28        // java/io/PrintStream.println:(I)V
   #5 = Class              #29            // com/atguigu/spring5/test1/Hello
   #6 = Class              #30            // java/lang/Object
   #7 = Utf8               a
   #8 = Utf8               I
   #9 = Utf8               <init>
  #10 = Utf8               ()V
  #11 = Utf8               Code
  #12 = Utf8               LineNumberTable
  #13 = Utf8               LocalVariableTable
  #14 = Utf8               this
  #15 = Utf8               Lcom/atguigu/spring5/test1/Hello;
  #16 = Utf8               main
  #17 = Utf8               ([Ljava/lang/String;)V
  #18 = Utf8               args
  #19 = Utf8               [Ljava/lang/String;
  #20 = Utf8               <clinit>
  #21 = Utf8               SourceFile
  #22 = Utf8               Hello.java
  #23 = NameAndType        #9:#10         // "<init>":()V
  #24 = Class              #31            // java/lang/System
  #25 = NameAndType        #32:#33        // out:Ljava/io/PrintStream;
  #26 = NameAndType        #7:#8          // a:I
  #27 = Class              #34            // java/io/PrintStream
  #28 = NameAndType        #35:#36        // println:(I)V
  #29 = Utf8               com/atguigu/spring5/test1/Hello
  #30 = Utf8               java/lang/Object
  #31 = Utf8               java/lang/System
  #32 = Utf8               out
  #33 = Utf8               Ljava/io/PrintStream;
  #34 = Utf8               java/io/PrintStream
  #35 = Utf8               println
  #36 = Utf8               (I)V
{
  public com.atguigu.spring5.test1.Hello();
    descriptor: ()V
    flags: (0x0001) 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/atguigu/spring5/test1/Hello;

  public static void main(java.lang.String[]);
    descriptor: ([Ljava/lang/String;)V
    flags: (0x0009) ACC_PUBLIC, ACC_STATIC
    Code:
      stack=2, locals=1, args_size=1
         0: getstatic     #2                  // Field java/lang/System.out:Ljava/io/PrintStream;
         3: getstatic     #3                  // Field a:I
         6: invokevirtual #4                  // Method java/io/PrintStream.println:(I)V
         9: return
      LineNumberTable:
        line 6: 0
        line 7: 9
      LocalVariableTable:
        Start  Length  Slot  Name   Signature
            0      10     0  args   [Ljava/lang/String;

  static {};
    descriptor: ()V
    flags: (0x0008) ACC_STATIC
    Code:
      stack=1, locals=0, args_size=0
         0: iconst_1
         1: putstatic     #3                  // Field a:I
         4: return
      LineNumberTable:
        line 4: 0
}
SourceFile: "Hello.java"