空手套白狼,硬阅java字节码class文件

Offset A B C D E F CA FE BA BE 6A 0A 1C 0A 漱壕 j
3A 3B 3C 3D : ; < =
3E 0A 3F 0A > ? @ A
0A 0A 0A B C D
0A 0A 0A 0A E F G H I
0A 0A 4A 0B 4B 4C 4D 0A J K L M
0A 4E 4F 0A N O
0A 0A 0A P Q R
0B S T userServi
4C 6F 6D 2F 6F 2F ce $Lcom/youge/
000000A0 2F 2F service/user/Use
000000B0 3B 6E rService; init
000000C0 6C 5A 3C 6E ialed Z <ini
000000D0 3E 6F t> ()V Code

package com.youge.api;import com.youge.pojo.user.UserInfo;
import com.youge.service.user.UserService;
import com.youge.service.user.UserServiceImpl;public class ByteCodeClassKen { private UserService userService; private boolean initialed; public ByteCodeClassKen() {
init();
} private void init() {
if(!initialed) {
System.out.println("init...");
userService = new UserServiceImpl();
initialed = true;
}
} public Integer addUser() throws Exception {
UserInfo userInfo = new UserInfo();
userInfo.setName("lilei");
userInfo.setAge(12);
userInfo.setAddress("new road.");
return userService.addUser(userInfo);
} public static void main(String[] args) throws Exception {
// test
ByteCodeClassKen classKen = new ByteCodeClassKen();
Integer affect = classKen.addUser();
System.out.println("affect: " + affect);
}
}

type descriptor remark
u4 magic 0xCAFEBABE
u2 minor_version
u2 major_version
u2 constant_pool_count
cp_info constant_pool[cosntant_pool_count – ] index  is invalid
u2 access_flags
u2 this_class
u2 super_class
u2 interfaces_count
u2 interfaces[interfaces_count]
u2 fields_count
field_info fields[fields_count]
u2 methods_count
method_info methods[methods_count]
u2 attributes_count
attribute_info attributes[attributes_count]

tag名称 remarktag值
CONSTANT_Utf8_info 记录字符串的值
CONSTANT_Integer_info 用于记录int类型的常量值
CONSTANT_Float_info 用于记录float类型的常量值
CONSTANT_Long_info 用于记录long类型的常量值
CONSTANT_Double_info 用于记录double类型的常量值
CONSTANT_Class_info 用于记录类或接口名
CONSTANT_String_info 用于记录常量字符串的值
CONSTANT_Fieldref_info 用于记录字段信息（包括类或接口中定义的字段以及代码中使用到的字段）
CONSTANT_Methodref_info 用于记录方法信息（包括类中定义的方法以及代码中使用到的方法）
CONSTANT_InterfaceMethodref_info 用于记录接口中的方法信息（包括接口中定义的方法以及代码中使用到的方法）
CONSTANT_NameAndType_info 记录方法或字段的名称(name)和描述符(descriptor)
CONSTANT_MethodHandle_info 方法句柄表,.7增加
CONSTANT_MethodType_info 方法类型表,.7增加
CONSTANT_InvokeDynamic_info 动态方法调用点,.7增加

Flag Name Value Remarks
ACC_PUBLIC 0x0001 pubilc，包外可访问。
ACC_FINAL 0x0010 final，不能有子类。
ACC_SUPER 0x0020 用于兼容早期编译器，新编译器都设置该标记，以在使用 invokespecial指令时对子类方法做特定处理。
ACC_INTERFACE 0x0200 接口，同时需要设置：ACC_ABSTRACT。不可同时设置：ACC_FINAL、ACC_SUPER、ACC_ENUM
ACC_ABSTRACT 0x0400 抽象类，无法实例化。不可和ACC_FINAL同时设置。
ACC_SYNTHETIC 0x1000 synthetic，由编译器产生，不存在于源代码中。 ACC_ANNOTATION 0x2000 注解类型（annotation），需同时设置：ACC_INTERFACE、ACC_ABSTRACT
ACC_ENUM 0x4000 枚举类型

type descriptor remark
u2 access_flags 记录字段的访问权限。
u2 name_index constant_pool中的索引，CONSTANT_Utf8_info类型。指定字段的名称。
u2 descriptor_index constant_pool中的索引，CONSTANT_Utf8_info类型，指定字段的描述符（见附录C）。
u2 attributes_count attributes包含的项目数。
attribute_info attributes[attributes_count]

type descriptor remark
u2 access_flags 记录方法的访问权限。见2.9.1
u2 name_index constant_pool中的索引，CONSTANT_Utf8_info类型。指定方法名称。
u2 descriptor_index constant_pool中的索引，CONSTANT_Utf8_info类型，指定方法的描述符（见附录C）。
u2 attributes_count attributes包含的项目数。
attribute_info attributes[attributes_count] 字段中包含的Attribute集合。

Offset 3B 2A B7 # ; *? 2A B7 B1 *? ? $ 0E 0C % & ' ( " # c 2A B4 9A 1B B2 *? ? ? B6 2A BB B7 B5 ? *? Y? ? 2A B5 B1 * ? ? $ 0F 1A 1A 1F 1C 0C % & ' ) 1F 2A 2B 6C * + # l BB 0A B7 0B 4C (? Y? L 2B 0C B6 0D 2B 0C B8 0E B6 0F 2B + ? + ? ? + B6 2A B4 2B B9 B0 ? *? +? ?

type descriptor remark
u2 attribute_name_index constant_pool中的索引，CONSTANT_Utf8_info类型。指定Attribute的名称("Code")。
u4 attribute_length 该Attribute内容的字节长度。
u2 max_stack 该方法操作栈的最大深度。
u2 max_locals 该方法调用时需要分配的局部变量的最大个数，包括该方法的参数。
u4 code_length 该方法字节码长度（以字节为单位）
u1 code[code_length] 存放字节码数组（字节码如何解析？）。
u2 exception_table_length 异常表的长度。
exception_table_info 每个表项记录一段异常处理代码信息和范围。
u2 start_pc 记录应用该项异常处理的起始字节码。在字节码数组中的起始索引号[start_pc, end_pc)。索引号必须是opcode（一条指令的开始位置）对应的位置。
u2 end_pc u2
handler_pc 记录该项异常处理代码的开始地址。在字节码数组中的开始索引号。索引号必须是opcode对应的位置。
u2 catch_type constant_pool中的索引，CONSTANT_Class_info类型。指定该项能捕获的异常类（或其子类）。或0用于实现finally语法（即不管什么类型都会捕获。）
exception_table[exception_table_length]
u2 attributes_count attributes包含的项目数。
attribute_info attributes[attributes_count]

Classfile /D:/www/test/target/classes/com/youge/api/ByteCodeClassKen.class
Last modified 2018-9-26; size 1801 bytes
MD5 checksum 76e207e502c3b096346480457d98cdef
Compiled from "ByteCodeClassKen.java"
public class com.youge.api.ByteCodeClassKen
minor version: 0
major version: 52
flags: ACC_PUBLIC, ACC_SUPER
Constant pool:
#1 = Methodref #28.#57 // java/lang/Object."<init>":()V
#2 = Methodref #19.#58 // com/youge/api/ByteCodeClassKen.init:()V
#3 = Fieldref #19.#59 // com/youge/api/ByteCodeClassKen.initialed:Z
#4 = Fieldref #60.#61 // java/lang/System.out:Ljava/io/PrintStream;
#5 = String #62 // init...
#6 = Methodref #63.#64 // java/io/PrintStream.println:(Ljava/lang/String;)V
#7 = Class #65 // com/youge/service/user/UserServiceImpl
#8 = Methodref #7.#57 // com/youge/service/user/UserServiceImpl."<init>":()V
#9 = Fieldref #19.#66 // com/youge/api/ByteCodeClassKen.userService:Lcom/youge/service/user/UserService;
#10 = Class #67 // com/youge/pojo/user/UserInfo
#11 = Methodref #10.#57 // com/youge/pojo/user/UserInfo."<init>":()V
#12 = String #68 // lilei
#13 = Methodref #10.#69 // com/youge/pojo/user/UserInfo.setName:(Ljava/lang/String;)V
#14 = Methodref #70.#71 // java/lang/Integer.valueOf:(I)Ljava/lang/Integer;
#15 = Methodref #10.#72 // com/youge/pojo/user/UserInfo.setAge:(Ljava/lang/Integer;)V
#16 = String #73 // new road.
#17 = Methodref #10.#74 // com/youge/pojo/user/UserInfo.setAddress:(Ljava/lang/String;)V
#18 = InterfaceMethodref #75.#76 // com/youge/service/user/UserService.addUser:(Lcom/youge/pojo/user/UserInfo;)Ljava/lang/Integer;
#19 = Class #77 // com/youge/api/ByteCodeClassKen
#20 = Methodref #19.#57 // com/youge/api/ByteCodeClassKen."<init>":()V
#21 = Methodref #19.#78 // com/youge/api/ByteCodeClassKen.addUser:()Ljava/lang/Integer;
#22 = Class #79 // java/lang/StringBuilder
#23 = Methodref #22.#57 // java/lang/StringBuilder."<init>":()V
#24 = String #80 // affect:
#25 = Methodref #22.#81 // java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
#26 = Methodref #22.#82 // java/lang/StringBuilder.append:(Ljava/lang/Object;)Ljava/lang/StringBuilder;
#27 = Methodref #22.#83 // java/lang/StringBuilder.toString:()Ljava/lang/String;
#28 = Class #84 // java/lang/Object
#29 = Utf8 userService
#30 = Utf8 Lcom/youge/service/user/UserService;
#31 = Utf8 initialed
#32 = Utf8 Z
#33 = Utf8 <init>
#34 = Utf8 ()V
#35 = Utf8 Code
#36 = Utf8 LineNumberTable
#37 = Utf8 LocalVariableTable
#38 = Utf8 this
#39 = Utf8 Lcom/youge/api/ByteCodeClassKen;
#40 = Utf8 init
#41 = Utf8 StackMapTable
#42 = Utf8 addUser
#43 = Utf8 ()Ljava/lang/Integer;
#44 = Utf8 userInfo
#45 = Utf8 Lcom/youge/pojo/user/UserInfo;
#46 = Utf8 Exceptions
#47 = Class #85 // java/lang/Exception
#48 = Utf8 main
#49 = Utf8 ([Ljava/lang/String;)V
#50 = Utf8 args
#51 = Utf8 [Ljava/lang/String;
#52 = Utf8 classKen
#53 = Utf8 affect
#54 = Utf8 Ljava/lang/Integer;
#55 = Utf8 SourceFile
#56 = Utf8 ByteCodeClassKen.java
#57 = NameAndType #33:#34 // "<init>":()V
#58 = NameAndType #40:#34 // init:()V
#59 = NameAndType #31:#32 // initialed:Z
#60 = Class #86 // java/lang/System
#61 = NameAndType #87:#88 // out:Ljava/io/PrintStream;
#62 = Utf8 init...
#63 = Class #89 // java/io/PrintStream
#64 = NameAndType #90:#91 // println:(Ljava/lang/String;)V
#65 = Utf8 com/youge/service/user/UserServiceImpl
#66 = NameAndType #29:#30 // userService:Lcom/youge/service/user/UserService;
#67 = Utf8 com/youge/pojo/user/UserInfo
#68 = Utf8 lilei
#69 = NameAndType #92:#91 // setName:(Ljava/lang/String;)V
#70 = Class #93 // java/lang/Integer
#71 = NameAndType #94:#95 // valueOf:(I)Ljava/lang/Integer;
#72 = NameAndType #96:#97 // setAge:(Ljava/lang/Integer;)V
#73 = Utf8 new road.
#74 = NameAndType #98:#91 // setAddress:(Ljava/lang/String;)V
#75 = Class #99 // com/youge/service/user/UserService
#76 = NameAndType #42:#100 // addUser:(Lcom/youge/pojo/user/UserInfo;)Ljava/lang/Integer;
#77 = Utf8 com/youge/api/ByteCodeClassKen
#78 = NameAndType #42:#43 // addUser:()Ljava/lang/Integer;
#79 = Utf8 java/lang/StringBuilder
#80 = Utf8 affect:
#81 = NameAndType #101:#102 // append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
#82 = NameAndType #101:#103 // append:(Ljava/lang/Object;)Ljava/lang/StringBuilder;
#83 = NameAndType #104:#105 // toString:()Ljava/lang/String;
#84 = Utf8 java/lang/Object
#85 = Utf8 java/lang/Exception
#86 = Utf8 java/lang/System
#87 = Utf8 out
#88 = Utf8 Ljava/io/PrintStream;
#89 = Utf8 java/io/PrintStream
#90 = Utf8 println
#91 = Utf8 (Ljava/lang/String;)V
#92 = Utf8 setName
#93 = Utf8 java/lang/Integer
#94 = Utf8 valueOf
#95 = Utf8 (I)Ljava/lang/Integer;
#96 = Utf8 setAge
#97 = Utf8 (Ljava/lang/Integer;)V
#98 = Utf8 setAddress
#99 = Utf8 com/youge/service/user/UserService
#100 = Utf8 (Lcom/youge/pojo/user/UserInfo;)Ljava/lang/Integer;
#101 = Utf8 append
#102 = Utf8 (Ljava/lang/String;)Ljava/lang/StringBuilder;
#103 = Utf8 (Ljava/lang/Object;)Ljava/lang/StringBuilder;
#104 = Utf8 toString
#105 = Utf8 ()Ljava/lang/String;
{
public com.youge.api.ByteCodeClassKen();
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: aload_0
5: invokespecial #2 // Method init:()V
8: return
LineNumberTable:
line 18: 0
line 19: 4
line 20: 8
LocalVariableTable:
Start Length Slot Name Signature
0 9 0 this Lcom/youge/api/ByteCodeClassKen; public java.lang.Integer addUser() throws java.lang.Exception;
descriptor: ()Ljava/lang/Integer;
flags: ACC_PUBLIC
Code:
stack=2, locals=2, args_size=1
0: new #10 // class com/youge/pojo/user/UserInfo
3: dup
4: invokespecial #11 // Method com/youge/pojo/user/UserInfo."<init>":()V
7: astore_1
8: aload_1
9: ldc #12 // String lilei
11: invokevirtual #13 // Method com/youge/pojo/user/UserInfo.setName:(Ljava/lang/String;)V
14: aload_1
15: bipush 12
17: invokestatic #14 // Method java/lang/Integer.valueOf:(I)Ljava/lang/Integer;
20: invokevirtual #15 // Method com/youge/pojo/user/UserInfo.setAge:(Ljava/lang/Integer;)V
23: aload_1
24: ldc #16 // String new road.
26: invokevirtual #17 // Method com/youge/pojo/user/UserInfo.setAddress:(Ljava/lang/String;)V
29: aload_0
30: getfield #9 // Field userService:Lcom/youge/service/user/UserService;
33: aload_1
34: invokeinterface #18, 2 // InterfaceMethod com/youge/service/user/UserService.addUser:(Lcom/youge/pojo/user/UserInfo;)Ljava/lang/Integer;
39: areturn
LineNumberTable:
line 31: 0
line 32: 8
line 33: 14
line 34: 23
line 35: 29
LocalVariableTable:
Start Length Slot Name Signature
0 40 0 this Lcom/youge/api/ByteCodeClassKen;
8 32 1 userInfo Lcom/youge/pojo/user/UserInfo;
Exceptions:
throws java.lang.Exception public static void main(java.lang.String[]) throws java.lang.Exception;
descriptor: ([Ljava/lang/String;)V
flags: ACC_PUBLIC, ACC_STATIC
Code:
stack=3, locals=3, args_size=1
0: new #19 // class com/youge/api/ByteCodeClassKen
3: dup
4: invokespecial #20 // Method "<init>":()V
7: astore_1
8: aload_1
9: invokevirtual #21 // Method addUser:()Ljava/lang/Integer;
12: astore_2
13: getstatic #4 // Field java/lang/System.out:Ljava/io/PrintStream;
16: new #22 // class java/lang/StringBuilder
19: dup
20: invokespecial #23 // Method java/lang/StringBuilder."<init>":()V
23: ldc #24 // String affect:
25: invokevirtual #25 // Method java/lang/StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
28: aload_2
29: invokevirtual #26 // Method java/lang/StringBuilder.append:(Ljava/lang/Object;)Ljava/lang/StringBuilder;
32: invokevirtual #27 // Method java/lang/StringBuilder.toString:()Ljava/lang/String;
35: invokevirtual #6 // Method java/io/PrintStream.println:(Ljava/lang/String;)V
38: return
LineNumberTable:
line 40: 0
line 41: 8
line 42: 13
line 43: 38
LocalVariableTable:
Start Length Slot Name Signature
0 39 0 args [Ljava/lang/String;
8 31 1 classKen Lcom/youge/api/ByteCodeClassKen;
13 26 2 affect Ljava/lang/Integer;
Exceptions:
throws java.lang.Exception
}
SourceFile: "ByteCodeClassKen.java"