バイナリビューアを使ってクラスファイルを読んでみよう！

セッション資料
- バイナリビューアを使ってクラスファイルを読んでみよう #jjug_ccc
ソースコード
- Main.java
クラスファイル
- Main.class
javap 出力
- Main.javap

クラスファイルのバイナリー

00000000  ca fe ba be 00 00 00 41  00 26 0a 00 02 00 03 07  |.......A.&......|
00000010  00 04 0c 00 05 00 06 01  00 10 6a 61 76 61 2f 6c  |..........java/l|
00000020  61 6e 67 2f 4f 62 6a 65  63 74 01 00 06 3c 69 6e  |ang/Object...<in|
00000030  69 74 3e 01 00 03 28 29  56 09 00 08 00 09 07 00  |it>...()V.......|
00000040  0a 0c 00 0b 00 0c 01 00  10 6a 61 76 61 2f 6c 61  |.........java/la|
00000050  6e 67 2f 53 79 73 74 65  6d 01 00 03 6f 75 74 01  |ng/System...out.|
00000060  00 15 4c 6a 61 76 61 2f  69 6f 2f 50 72 69 6e 74  |..Ljava/io/Print|
00000070  53 74 72 65 61 6d 3b 08  00 0e 01 00 15 e9 a0 91  |Stream;.........|
00000080  e5 bc b5 e3 82 8a e3 81  be e3 81 99 ed a0 bd ed  |................|
00000090  b9 82 0a 00 10 00 11 07  00 12 0c 00 13 00 14 01  |................|
000000a0  00 13 6a 61 76 61 2f 69  6f 2f 50 72 69 6e 74 53  |..java/io/PrintS|
000000b0  74 72 65 61 6d 01 00 07  70 72 69 6e 74 6c 6e 01  |tream...println.|
000000c0  00 15 28 4c 6a 61 76 61  2f 6c 61 6e 67 2f 53 74  |..(Ljava/lang/St|
000000d0  72 69 6e 67 3b 29 56 07  00 16 01 00 04 4d 61 69  |ring;)V......Mai|
000000e0  6e 01 00 07 54 57 49 54  54 45 52 01 00 12 4c 6a  |n...TWITTER...Lj|
000000f0  61 76 61 2f 6c 61 6e 67  2f 53 74 72 69 6e 67 3b  |ava/lang/String;|
00000100  01 00 0d 43 6f 6e 73 74  61 6e 74 56 61 6c 75 65  |...ConstantValue|
00000110  08 00 1b 01 00 0d 40 59  75 6a 69 53 6f 66 74 77  |......@YujiSoftw|
00000120  61 72 65 01 00 03 41 47  45 01 00 01 4a 05 00 00  |are...AGE...J...|
00000130  00 00 00 00 00 26 01 00  04 43 6f 64 65 01 00 0f  |.....&...Code...|
00000140  4c 69 6e 65 4e 75 6d 62  65 72 54 61 62 6c 65 01  |LineNumberTable.|
00000150  00 04 6d 61 69 6e 01 00  16 28 5b 4c 6a 61 76 61  |..main...([Ljava|
00000160  2f 6c 61 6e 67 2f 53 74  72 69 6e 67 3b 29 56 01  |/lang/String;)V.|
00000170  00 0a 53 6f 75 72 63 65  46 69 6c 65 01 00 09 4d  |..SourceFile...M|
00000180  61 69 6e 2e 6a 61 76 61  00 21 00 15 00 02 00 00  |ain.java.!......|
00000190  00 02 00 19 00 17 00 18  00 01 00 19 00 00 00 02  |................|
000001a0  00 1a 00 19 00 1c 00 1d  00 01 00 19 00 00 00 02  |................|
000001b0  00 1e 00 02 00 01 00 05  00 06 00 01 00 20 00 00  |............. ..|
000001c0  00 1d 00 01 00 01 00 00  00 05 2a b7 00 01 b1 00  |..........*.....|
000001d0  00 00 01 00 21 00 00 00  06 00 01 00 00 00 01 00  |....!...........|
000001e0  09 00 22 00 23 00 01 00  20 00 00 00 25 00 02 00  |..".#... ...%...|
000001f0  01 00 00 00 09 b2 00 07  12 0d b6 00 0f b1 00 00  |................|
00000200  00 01 00 21 00 00 00 0a  00 02 00 00 00 06 00 08  |...!............|
00000210  00 07 00 01 00 24 00 00  00 02 00 25              |.....$.....%|
0000021c

解析データ

magic: ca fe ba be
minor_version: 00 00
major_version: 00 41
constant_pool_count: 00 26
constant_pool:
- #0001:
  - tag: 0a (CONSTANT_Methodref)
  - class_index: 00 02
  - name_and_type_index: 00 03
- #0002:
  - tag: 07 (CONSTANT_Class)
  - name_index: 00 04
- #0003:
  - tag: 0c (CONSTANT_NameAndType)
  - name_index: 00 05
  - descriptor_index: 00 06
- #0004:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 10
  - bytes: 6a 61 76 61 2f 6c 61 6e 67 2f 4f 62 6a 65 63 74 (java/lang/Object)
- #0005:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 06
  - bytes: 3c 69 6e 69 74 3e ()
- #0006:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 03
  - bytes: 28 29 56 (()V)
- #0007:
  - tag: 09 (CONSTANT_Fieldref)
  - class_index: 00 08
  - name_and_type_index: 00 09
- #0008:
  - tag: 07 (CONSTANT_Class)
  - name_index: 00 0a
- #0009:
  - tag: 0c (CONSTANT_Fieldref)
  - class_index: 00 0b
  - name_and_type_index: 00 0c
- #000A:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 10
  - bytes: 6a 61 76 61 2f 6c 61 6e 67 2f 53 79 73 74 65 6d (java/lang/System)
- #000B:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 03
  - bytes: 6f 75 74 (out)
- #000C:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 15
  - bytes: 4c 6a 61 76 61 2f 69 6f 2f 50 72 69 6e 74 53 74 72 65 61 6d 3b (Ljava/io/PrintStream;)
- #000D:
  - tag: 08 (CONSTANT_String)
  - string_index: 00 0e
- #000E:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 15
  - bytes: e9 a0 91 e5 bc b5 e3 82 8a e3 81 be e3 81 99 ed a0 bd ed b9 82 (頑張ります🙂)
- #000F:
  - tag: 0a (CONSTANT_NameAndType)
  - class_index: 00 10
  - descriptor_index: 00 11
- #0010:
  - tag: 07 (CONSTANT_Class)
  - name_index: 00 12
- #0011:
  - tag: 0c (CONSTANT_NameAndType)
  - name_index: 00 13
  - descriptor_index: 00 14
- #0012:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 13
  - bytes: 6a 61 76 61 2f 69 6f 2f 50 72 69 6e 74 53 74 72 65 61 6d (java/io/PrintStream)
- #0013:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 07
  - bytes: 70 72 69 6e 74 6c 6e (println)
- #0014:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 15
  - bytes: 28 4c 6a 61 76 61 2f 6c 61 6e 67 2f 53 74 72 69 6e 67 3b 29 56 ((Ljava/lang/String;)V)
- #0015:
  - tag: 07 (CONSTANT_Class)
  - name_index: 00 16
- #0016:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 04
  - bytes: 4d 61 69 6e (Main)
- #0017:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 07
  - bytes: 54 57 49 54 54 45 52 (TWITTER)
- #0018:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 12
  - bytes: 4c 6a 61 76 61 2f 6c 61 6e 67 2f 53 74 72 69 6e 67 3b (Ljava/lang/String;)
- #0019:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 0d
  - bytes: 43 6f 6e 73 74 61 6e 74 56 61 6c 75 65 (ConstantValue)
- #001A:
  - tag: 08 (CONSTANT_String)
  - string_index: 00 1b
- #001B:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 0d
  - bytes: 40 59 75 6a 69 53 6f 66 74 77 61 72 65 (@YujiSoftware)
- #001C:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 03
  - bytes: 41 47 45 (AGE)
- #001D:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 01
  - bytes: 4a (J)
- #001E:
  - tag: 05 (CONSTANT_Long)
  - high_bytes: 00 00 00 00
  - low_bytes: 00 00 00 26
- #0020:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 04
  - bytes: 43 6f 64 65 (Code)
- #0021:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 0f
  - bytes: 4c 69 6e 65 4e 75 6d 62 65 72 54 61 62 6c 65 (LineNumberTable)
- #0022:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 04
  - bytes: 6d 61 69 6e (main)
- #0023:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 16
  - bytes: 28 5b 4c 6a 61 76 61 2f 6c 61 6e 67 2f 53 74 72 69 6e 67 3b 29 56 (([Ljava/lang/String;)V)
- #0024:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 0a
  - bytes: 53 6f 75 72 63 65 46 69 6c 65 (SourceFile)
- #0025:
  - tag: 01 (CONSTANT_Utf8)
  - length: 00 09
  - bytes: 4d 61 69 6e 2e 6a 61 76 61 (Main.java)
access_flags: 00 21
this_class: 00 15
super_class: 00 02
interfaces_count: 00 00
interfaces:
fields_count: 00 02
fields:
- #0001:
  - access_flags: 00 19
  - name_index: 00 17
  - descriptor_index: 00 18
  - attributes_count: 00 01
  - attributes:
    - #0001:
      - attribute_name_index: 00 19 (ConstantValue)
      - attribute_length: 00 00 00 02
      - constantvalue_index: 00 1a
- #0002:
  - access_flags: 00 19
  - name_index: 00 1c
  - descriptor_index: 00 1d
  - attributes_count: 00 01
  - attributes:
    - #0001:
      - attribute_name_index: 00 19 (ConstantValue)
      - attribute_length: 00 00 00 02
      - constantvalue_index: 00 1e
methods_count: 00 02
methods:
- #0001:
  - access_flags: 00 01
  - name_index: 00 05
  - descriptor_index: 00 06
  - attributes_count: 00 01
  - attributes:
    - #0001:
      - attribute_name_index: 00 20 (Code)
      - attribute_length: 00 00 00 1d
      - max_stack: 00 01
      - max_locals: 00 01
      - code_length: 00 00 00 05
      - code:
        
        #00000000:
        
        instruction: 2a (aload_0)
        
        #00000001:
        
        instruction: b7 (invokespecial)
        
        indexbyte1: 00
        
        indexbyte2: 01
        
        #00000004:
        
        instruction: b1 (return)
      - exception_table_length: 00 00
      - exception_table:
      - attributes_count: 00 01
      - attributes:
        
        #0001:
        
        attribute_name_index: 00 21 (LineNumberTable)
        
        attribute_length: 00 00 00 06
        
        line_number_table_length: 00 01
        
        line_number_table:
        
        #0001:
        
        start_pc: 00 00
        
        line_number: 00 01
- #0002:
  - access_flags: 00 09
  - name_index: 00 22
  - descriptor_index: 00 23
  - attributes_count: 00 01
  - attributes:
    - #0001:
      - attribute_name_index: 00 20 (Code)
      - attribute_length: 00 00 00 25
      - max_stack: 00 02
      - max_locals: 00 01
      - code_length: 00 00 00 09
      - code:
        
        #00000000:
        
        instruction: b2 (getstatic)
        
        indexbyte1: 00
        
        indexbyte2: 07
        
        #00000003:
        
        instruction: 12 (ldc)
        
        index: 0d
        
        #00000005:
        
        instruction: b6 (invokevirtual)
        
        indexbyte1: 00
        
        indexbyte2: 0f
        
        #00000008:
        
        instruction: b1 (return)
      - exception_table_length: 00 00
      - exception_table:
      - attributes_count: 00 01
      - attributes:
        
        #0001:
        
        attribute_name_index: 00 21 (LineNumberTable)
        
        attribute_length: 00 00 00 0a
        
        line_number_table_length: 00 02
        
        line_number_table:
        
        #0001:
        
        start_pc: 00 00
        
        line_number: 00 06
        
        #0002:
        
        start_pc: 00 08
        
        line_number: 00 07
attributes_count: 00 01
attributes:
- #0001:
  - attribute_name_index: 00 24 (SourceFile)
  - attribute_length: 00 00 00 02
  - sourcefile_index: 00 25

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バイナリビューアを使ってクラスファイルを読んでみよう！

クラスファイルのバイナリー

解析データ

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Name		Name	Last commit message	Last commit date
Latest commit History 5 Commits
docs		docs
Main.class		Main.class
Main.java		Main.java
Main.javap		Main.javap
README.md		README.md

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バイナリビューアを使ってクラスファイルを読んでみよう！

クラスファイルのバイナリー

解析データ

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