每个颜色代表一种解析器
| 类型 | 字段 | 描述 |
|---|---|---|
| CONSTANT_Utf8_info | tag/length/bytes(u1) | UTF-8字符串 |
| CONSTANT_Integer_info | tag/bytes(u4) | int |
| CONSTANT_Float_info | tag/bytes(u4) | float |
| CONSTANT_Long_info | tag/bytes(u8) | long |
| CONSTANT_Double_info | tag/bytes(u8) | double |
| CONSTANT_Class_info | tag/index | 类或者接口符号引用 |
| CONSTANT_String_info | tag/index | 字符串类型字面量 |
| CONSTANT_Fieldref_info | tag/index类/index | 字段符号引用 |
| CONSTANT_Methodref_info | tag/index类/index | 类中方法符号引用 |
| CONSTANT_Interface-Methodref_info | tag/index接口类/index | 接口中方法符号引用 |
| CONSTANT_NameAndType_info | tag/index名称/index签名 | 字段或者方法的部分符号引用 |
| CONSTANT_Method-Handle_info | 方法句柄 | |
| CONSTANT_Method-type_info | 标识方法类型 | |
| CONSTANT_Invoke-Dynamic_info | 动态方法调用点 |
| 类型 | 描述 |
|---|---|
| Code | 方法表 |
| LineNumberTable | 调试表 |
| LocalVariableTable | 本地变量表 |
| SourceFile | 源文件表 |
| Exceptions | 异常表 |
| ConstantValue | 异常表 |
| InnerClasses | 内部类表 |
| Deprecated | 废弃标识 |
| Synthetic | 表示方法或者字段 |
| StackMapTable | 类型检查器 |
| Signature | 泛型的方法签名 - 泛型会类型擦除 |
| BootstrapMethods | invokedymic相关 |
| LocalVariableTypeTable | 泛型相关 |
| … | 还有很多其他未解析的表 |
- Person
public class Person {
public String name;
public int age;
public Person(String name, int age) {
this.name = name;
this.age = age;
}
public void play(String name) {
if (name.equals("basket")) {
System.out.println("篮球");
}
}
}- Person 解析
magic: CAFEBABE
minor: 0
major: 52
Constant pool:
#1 = [ name=CONSTANT_Methodref_info, classIndex=10, nameAndTypeIndex=27 ]
#2 = [ name=CONSTANT_Fieldref_info, classIndex=9, nameAndTypeIndex=28 ]
#3 = [ name=CONSTANT_Fieldref_info, classIndex=9, nameAndTypeIndex=29 ]
#4 = [ name=CONSTANT_String_info, index=30 ]
#5 = [ name=CONSTANT_Methodref_info, classIndex=31, nameAndTypeIndex=32 ]
#6 = [ name=CONSTANT_Fieldref_info, classIndex=33, nameAndTypeIndex=34 ]
#7 = [ name=CONSTANT_String_info, index=35 ]
#8 = [ name=CONSTANT_Methodref_info, classIndex=36, nameAndTypeIndex=37 ]
#9 = [ name=CONSTANT_Class_info, index=38 ]
#10 = [ name=CONSTANT_Class_info, index=39 ]
#11 = [ name=CONSTANT_Utf8_info, length=4, value='name ]
#12 = [ name=CONSTANT_Utf8_info, length=18, value='Ljava/lang/String; ]
#13 = [ name=CONSTANT_Utf8_info, length=3, value='age ]
#14 = [ name=CONSTANT_Utf8_info, length=1, value='I ]
#15 = [ name=CONSTANT_Utf8_info, length=6, value='<init> ]
#16 = [ name=CONSTANT_Utf8_info, length=22, value='(Ljava/lang/String;I)V ]
#17 = [ name=CONSTANT_Utf8_info, length=4, value='Code ]
#18 = [ name=CONSTANT_Utf8_info, length=15, value='LineNumberTable ]
#19 = [ name=CONSTANT_Utf8_info, length=18, value='LocalVariableTable ]
#20 = [ name=CONSTANT_Utf8_info, length=4, value='this ]
#21 = [ name=CONSTANT_Utf8_info, length=20, value='Lorg/example/Person; ]
#22 = [ name=CONSTANT_Utf8_info, length=4, value='play ]
#23 = [ name=CONSTANT_Utf8_info, length=21, value='(Ljava/lang/String;)V ]
#24 = [ name=CONSTANT_Utf8_info, length=13, value='StackMapTable ]
#25 = [ name=CONSTANT_Utf8_info, length=10, value='SourceFile ]
#26 = [ name=CONSTANT_Utf8_info, length=11, value='Person.java ]
#27 = [ name=CONSTANT_NameAndType_info, nameIndex=15, signatureIndex=40 ]
#28 = [ name=CONSTANT_NameAndType_info, nameIndex=11, signatureIndex=12 ]
#29 = [ name=CONSTANT_NameAndType_info, nameIndex=13, signatureIndex=14 ]
#30 = [ name=CONSTANT_Utf8_info, length=6, value='basket ]
#31 = [ name=CONSTANT_Class_info, index=41 ]
#32 = [ name=CONSTANT_NameAndType_info, nameIndex=42, signatureIndex=43 ]
#33 = [ name=CONSTANT_Class_info, index=44 ]
#34 = [ name=CONSTANT_NameAndType_info, nameIndex=45, signatureIndex=46 ]
#35 = [ name=CONSTANT_Utf8_info, length=6, value='篮球 ]
#36 = [ name=CONSTANT_Class_info, index=47 ]
#37 = [ name=CONSTANT_NameAndType_info, nameIndex=48, signatureIndex=23 ]
#38 = [ name=CONSTANT_Utf8_info, length=18, value='org/example/Person ]
#39 = [ name=CONSTANT_Utf8_info, length=16, value='java/lang/Object ]
#40 = [ name=CONSTANT_Utf8_info, length=3, value='()V ]
#41 = [ name=CONSTANT_Utf8_info, length=16, value='java/lang/String ]
#42 = [ name=CONSTANT_Utf8_info, length=6, value='equals ]
#43 = [ name=CONSTANT_Utf8_info, length=21, value='(Ljava/lang/Object;)Z ]
#44 = [ name=CONSTANT_Utf8_info, length=16, value='java/lang/System ]
#45 = [ name=CONSTANT_Utf8_info, length=3, value='out ]
#46 = [ name=CONSTANT_Utf8_info, length=21, value='Ljava/io/PrintStream; ]
#47 = [ name=CONSTANT_Utf8_info, length=19, value='java/io/PrintStream ]
#48 = [ name=CONSTANT_Utf8_info, length=7, value='println ]
flags: ACC_PUBLIC,ACC_SUPER
---------------------------------------
flags: ACC_PUBLIC
filed: name
descriptor: Ljava/lang/String;
---------------------------------------
flags: ACC_PUBLIC
filed: age
descriptor: I
---------------------------------------
flags: ACC_PUBLIC
method: <init>
descriptor: (Ljava/lang/String;I)V
Code:
maxStack=2 maxLocals=3
0: aload_0
1: invokespecial java/lang/Object <init> ()V
4: aload_0
5: aload_1
6: putfield org/example/Person name Ljava/lang/String;
9: aload_0
10: iload_2
11: putfield org/example/Person age I
14: return
LineNumberTable:
line 8：0
line 9：4
line 10：9
line 11：14
LocalVariableTable:
Start=0, Length=15, Slot=0, nameIndex=this, descriptorIndex=Lorg/example/Person;
Start=0, Length=15, Slot=1, nameIndex=name, descriptorIndex=Ljava/lang/String;
Start=0, Length=15, Slot=2, nameIndex=age, descriptorIndex=I
---------------------------------------
flags: ACC_PUBLIC
method: play
descriptor: (Ljava/lang/String;)V
Code:
maxStack=2 maxLocals=2
0: aload_1
1: ldc basket
3: invokevirtual java/lang/String equals (Ljava/lang/Object;)Z
6: ifeq name
9: getstatic java/lang/System out Ljava/io/PrintStream;
12: ldc 篮球
14: invokevirtual java/io/PrintStream println (Ljava/lang/String;)V
17: return
LineNumberTable:
line 15：0
line 16：9
line 18：17
LocalVariableTable:
Start=0, Length=18, Slot=0, nameIndex=this, descriptorIndex=Lorg/example/Person;
Start=0, Length=18, Slot=1, nameIndex=name, descriptorIndex=Ljava/lang/String;
StackMapTable:
frame_type=17
---------------------------------------
SourceFile:
Person.java
public interface Parse {
int parse(int start, byte[] code);
}- code：为class字节码
- start：解析器开始解析位置
- return：下一个解析器开始解析的位置
public class ClassFormat {
private List<Parse> parses = new ArrayList<>();
public ClassFormat() {
parses.add(new MagicParse()); //magic解析器
parses.add(new VersionParse()); // 版本解析器
parses.add(new ConstantParse()); // 常量池解析器
parses.add(new AccessFlagParse()); // class access flag解析器
parses.add(new ClassExtParse()); // class info解析器
parses.add(new InterfaceParse()); // class的接口解析器
parses.add(new FieldParse()); // field变量解析器
parses.add(new MethodParse()); // method方法解析器
parses.add(new AttributeParse()); // 类的其他属性解析器
}
public void parse(byte[] bytes) {
int start = 0;
for (Parse pars : parses) {
start = pars.parse(start, bytes);
}
}
}