Class文件解析器(1)-介绍

摘要：文件解析器解析器的名字随便起的关于对编译后的文件进行解析，目前已经完成了一大半，可能会写文章介绍一下划重点，可能。

解析器的名字[Ming](随便起的)

对Java编译后的Class文件进行解析，目前已经完成了一大半，可能会写文章介绍一下(划重点，可能)。

github: Ming

class文件使用的是MUTF-8的编码格式，与UTF-8有微妙的不同，在某些情况下可能错在无法解析的情况。

有一些类型虽然声明了，但是还没有具体的添加内容，（才不是因为懒呢），如果碰到没有实装的类型，会报错，我会尽量今早将所有的类型进行实装。

遇到没有实装类型的错误类型有两种

没有找到指定的属性类型："can"t find specific attribute"

没有找到指定的常量类型："can"t find specific type tag: [该常量类型所对应的具体的数值]"

支持JDK8及其以上版本

Simple.java

public class Simple implements Parent, Child{
    private int data;
    private static final String flag= "HelloWorld";
    private static final long num = 1L;
    private static final double dou = 0.1;
    public int add(int a, int b) {
      return a + b;
    }
}

Parent.java

public interface Parent {

}

Child.java

public interface Child {

}

参考文件

java com.ming.print.PrintClassInfo.java 具体信息的输出

java com.ming.test.Test.java 调用PrintClassInfo#printAll() 打印所有信息

[magic]: cafebabe
[minor_version]: 0
[major_version]: 52
[constant_pool_count]: 34
[constant_pool]: 
[1]: ConstantMethodrefInfo
[tag]: 10
[class_index]: 3-java/lang/Object
[name_and_type_index]: 28--()V

[2]: ConstantClassInfo
[tag]: 7
[name_index]: 29-Simple

[3]: ConstantClassInfo
[tag]: 7
[name_index]: 30-java/lang/Object

[4]: ConstantClassInfo
[tag]: 7
[name_index]: 31-Parent

[5]: ConstantClassInfo
[tag]: 7
[name_index]: 32-Child

[6]: ConstantUtf8Info
[tag]: 1
[length]: 4
[bytes]: data

[7]: ConstantUtf8Info
[tag]: 1
[length]: 1
[bytes]: I

[8]: ConstantUtf8Info
[tag]: 1
[length]: 4
[bytes]: flag

[9]: ConstantUtf8Info
[tag]: 1
[length]: 18
[bytes]: Ljava/lang/String;

[10]: ConstantUtf8Info
[tag]: 1
[length]: 13
[bytes]: ConstantValue

[11]: ConstantStringInfo
[tag]: 8
[string_index]: 33-HelloWorld

[12]: ConstantUtf8Info
[tag]: 1
[length]: 3
[bytes]: num

[13]: ConstantUtf8Info
[tag]: 1
[length]: 1
[bytes]: J

[14]: ConstantLongInfo
[tag]: 5
[value]: 01

[16]: ConstantUtf8Info
[tag]: 1
[length]: 3
[bytes]: dou

[17]: ConstantUtf8Info
[tag]: 1
[length]: 1
[bytes]: D

[18]: ConstantDoubleInfo
[tag]: 6
[value]: 3fb999999999999a

[20]: ConstantUtf8Info
[tag]: 1
[length]: 6
[bytes]: 

[21]: ConstantUtf8Info
[tag]: 1
[length]: 3
[bytes]: ()V

[22]: ConstantUtf8Info
[tag]: 1
[length]: 4
[bytes]: Code

[23]: ConstantUtf8Info
[tag]: 1
[length]: 15
[bytes]: LineNumberTable

[24]: ConstantUtf8Info
[tag]: 1
[length]: 3
[bytes]: add

[25]: ConstantUtf8Info
[tag]: 1
[length]: 5
[bytes]: (II)I

[26]: ConstantUtf8Info
[tag]: 1
[length]: 10
[bytes]: SourceFile

[27]: ConstantUtf8Info
[tag]: 1
[length]: 11
[bytes]: Simple.java

[28]: ConstantNameAndTypeInfo
[tag]: 12
[name_index]: 20-
[descriptor_index]: 21-()V

[29]: ConstantUtf8Info
[tag]: 1
[length]: 6
[bytes]: Simple

[30]: ConstantUtf8Info
[tag]: 1
[length]: 16
[bytes]: java/lang/Object

[31]: ConstantUtf8Info
[tag]: 1
[length]: 6
[bytes]: Parent

[32]: ConstantUtf8Info
[tag]: 1
[length]: 5
[bytes]: Child

[33]: ConstantUtf8Info
[tag]: 1
[length]: 10
[bytes]: HelloWorld

[access_flags]: 33
[this_class]: 2
[super_class]: 3
[interfaces_count]: 2
[interfaces]: 
[0]: 4-Parent
[1]: 5-Child

[fields_count]: 4
[fields]: 

[field 1 ]: 
[access_flags]: 2
[name_index]: 6
[descriptor_index]: 7
[attributes_count]: 0

[field 2 ]: 
[access_flags]: 26
[name_index]: 8
[descriptor_index]: 9
[attributes_count]: 1

[1]: AttributeConstantValueInfo
[attribute_name_index]: 10
[attribute_length]: 2
[constantvalue_index]: 11

[field 3 ]: 
[access_flags]: 26
[name_index]: 12
[descriptor_index]: 13
[attributes_count]: 1

[1]: AttributeConstantValueInfo
[attribute_name_index]: 10
[attribute_length]: 2
[constantvalue_index]: 14

[field 4 ]: 
[access_flags]: 26
[name_index]: 16
[descriptor_index]: 17
[attributes_count]: 1

[1]: AttributeConstantValueInfo
[attribute_name_index]: 10
[attribute_length]: 2
[constantvalue_index]: 18


[methods_count]: 2
[methods]: 

[method 1 ]: 
[access_flags]: 1
[name_index]: 20
[descriptor_index]: 21
[attributes_count]: 1

[1]: AttributeCodeInfo
[attribute_name_index]: 22
[attribute_length]: 29
[max_stack]: 1
[max_locals]: 1
[code_length]: 5
42-aload_0
183-invokespecial
0-nop
1-aconst_null
177-return_
[exception_table_length]: 0
[attributes_count]: 1

[method 2 ]: 
[access_flags]: 1
[name_index]: 24
[descriptor_index]: 25
[attributes_count]: 1

[1]: AttributeCodeInfo
[attribute_name_index]: 22
[attribute_length]: 28
[max_stack]: 2
[max_locals]: 3
[code_length]: 4
27-iload_1
28-iload_2
96-iadd
172-ireturn
[exception_table_length]: 0
[attributes_count]: 1


[attributes_count]: 1
[attributes]: 

[0]: AttributeSourceFileInfo
[attribute_name_index]: 26
[attribute_length]: 2
[sourcefile_index]: 27