class文件格式中的屬性信息

時間 2019-12-05

標籤 class 文件格式屬性信息简体版

原文原文鏈接

附加屬性（Attributes）被用於ClassFile, field_info, method_info，Code_attribute結構中。bootstrap

數據結構：數組

attribute_info {
    u2 attribute_name_index;        //unsigned 16-bit ->  CONSTANT_Utf8_info
    u4 attribute_length;            //bytes
    u1 info[attribute_length];
}

aadfadfadfadfadf數據結構

屬性 | class版本 | Java SE版本 | 位置 | 類型 | 做用 | 說明 ---|---|---|---|--|---|---- ConstantValue | 45.3 | 1.0.2 | field_info | F | 用於常量初始化賦值,如沒有常量字段則忽略 | 必有 Code | 45.3 | 1.0.2 | method_info | V | JVM指令，包括構造器 | 必有 StackMapTable | 50.0 | 6 | Code | V | 在運行時，提供類型檢查（可直接經過table，而不須要類型推測） | 必有 Exceptions | 45.3 | 1.0.2 | method_info | V | 方法可能拋出的異常（checked） | 必有 InnerClasses | 45.3 | 1.0.2 | ClassFile | V | 內部類 | 可選，JavaSE EnclosingMethod | 49.0 | 5.0 | ClassFile | F | 僅當局部類、匿名內部類 | 可選，JavaSE Synthetic | 45.3 | 1.1 | ClassFile, field_info, method_info | F | 非源碼/編譯器產生（不包括實例初始化方法；類/接口初始化方法；Enum.values();Enum.valueOf()）|可選，JavaSE Signature | 49.0 | 5.0 | ClassFile, field_info, method_info | F | 簽名；主要用於反射/DEBUG/{B C D F I J S Z;V;...} | 可選，JavaSE SourceFile | 45.3 | 1.0.2 | ClassFile | F | 最多一個 | 可選，JavaSE SourceDebugExtension | 49.0 | 5.0 | ClassFile | V | 可選，最多一個；擴展的DEBUG信息 | 可選，元數據，JavaSE LineNumberTable | 45.3 | 1.0.2 | Code | V | code對應的源碼行數 | 可選，JavaSE LocalVariableTable | 45.3 | 1.0.2 | Code | V | 在運行期方便的跟蹤局部變量/參數（槽位Slot分佈） | 可選，JavaSE LocalVariableTypeTable | 49.0 | 5.0 | Code | V | 在運行期方便的跟蹤局部變量/參數 | 可選，JavaSE Deprecated | 45.3 | 1.1 | ClassFile, field_info, method_info | F | 標記性 | 可選，元數據，JavaSE RuntimeVisibleAnnotations | 49.0 | 5.0 | ClassFile,field_info,method_info | V | 聲明註解運行時可見 | 可選，元數據，JavaSE RuntimeInvisibleAnnotations | 49.0 | 5.0 | ClassFile,field_info,method_info | V | 聲明註解運行時不可見 | 可選，元數據，JavaSE RuntimeVisibleParameterAnnotations | 49.0 | 5.0 | method_info | V | 運行時，參數的註解可見 | 可選，元數據，JavaSE RuntimeInvisibleParameterAnnotations | 49.0 | 5.0 | method_info | V | 運行時，參數的註解不可見 | 可選，元數據，JavaSE RuntimeVisibleTypeAnnotations | 52.0 | 8 | ClassFile,field_info,method_info, Code | V | 用於聲明式/表達式的運行時可見註解 | 可選，元數據，JavaSE RuntimeInvisibleTypeAnnotations | 52.0 | 8 | ClassFile,field_info,method_info, Code | V | 用於聲明式/表達式的運行時不可見註解 | 可選，元數據，JavaSE AnnotationDefault | 49.0 | 5.0 | method_info | V | 註解默認值（default關鍵字） | 可選，元數據，JavaSE BootstrapMethods | 51.0 | 7 | ClassFile | V | 記錄動態方法信息（被invokedynamic指令調用）；須要與CONSTANT_InvokeDynamic_info對應 | 必有 MethodParameters | 52.0 | 8 | method_info | V | 用於記錄表達式形式的方法參數 | 可選，元數據，JavaSE Module | 53.0 | 9 | ClassFile | V | 用於標記JAVA 9的模塊 | 可選，元數據，JavaSE ModulePackages | 53.0 | 9 | ClassFile | V | 包括全部exported或opened的Module屬性 | 可選，元數據，JavaSE ModuleMainClass | 53.0 | 9 | ClassFile | F | 指明Module的主類 | 可選，元數據，JavaSEapp

ConstantValue

ConstantValue_attribute {
    u2 attribute_name_index;        //CONSTANT_Utf8_info
    u4 attribute_length;
    u2 constantvalue_index;         //constant_pool中的一個值
}

Constant value attribute types：ide

Field Type	Entry Type
long	CONSTANT_Long
float	CONSTANT_Float
double	CONSTANT_Double
int, short, char, byte, boolean	CONSTANT_Integer
String	CONSTANT_String

Code

Code_attribute {
    u2 attribute_name_index;                        // CONSTANT_Utf8_info -> constant_pool -> "Code"
    u4 attribute_length;                            // excluding the initial six bytes
    u2 max_stack;                                   
    u2 max_locals;                                  // local variables/parameters/long or double is max_locals - 2
    u4 code_length;                                 // (0,65536)
    u1 code[code_length];                           // 讀入內存後可按字節尋址（byte-addressable），
                                                    // 數組起始（第一個字節）位置按4字節對齊
                                                    //（tableswitch and lookupswitch 32-bit offsets will be 4-byte aligned）
    u2 exception_table_length;                      // number of entries in the exception_table table
    { 
        u2 start_pc;                                // ranges in the code array [start_pc, end_pc)
        u2 end_pc;                                  // ranges in the code array [start_pc, end_pc)
        u2 handler_pc;                              // 
        u2 catch_type;                              // CONSTANT_Class_info -> constant_pool
                                                    // zero, => finally
    } exception_table[exception_table_length];  
    u2 attributes_count;                            // 
    attribute_info attributes[attributes_count];    // optional
}

StackMapTable
- 棧圖，其方法的code屬性中存儲了局部變量和操做數的類型驗證以及字節碼的偏移量
- 必須準確知道每一個字節碼指令對應的局部變量和操做數棧的類型
- 由於Java7在編譯的時期作了一些驗證期間要作的事情，那就是類型檢查，也就是棧圖包含的內容
- 代碼跳轉，分支，goto時，對變量和指令進行校驗
- 第一個隱式

StackMapTable_attribute {
    u2 attribute_name_index;                        // CONSTANT_Utf8_info -> constant_pool -> "StackMapTable"
    u4 attribute_length;                            // excluding the initial six bytes
    u2 number_of_entries;                           // the number of stack_map_frame entries in the entries table
    stack_map_frame entries[number_of_entries];     // stack map frame
}

union verification_type_info {
    Top_variable_info;
    Integer_variable_info;
    Float_variable_info;
    Long_variable_info;
    Double_variable_info;
    Null_variable_info;
    UninitializedThis_variable_info;
    Object_variable_info;
    Uninitialized_variable_info;
}

Top_variable_info {
    u1 tag = ITEM_Top; /* 0 */
}

Integer_variable_info {
    u1 tag = ITEM_Integer; /* 1 */
}

Float_variable_info {
    u1 tag = ITEM_Float; /* 2 */
}

Double_variable_info {
    u1 tag = ITEM_Double; /* 3 */
}

Long_variable_info {
    u1 tag = ITEM_Long; /* 4 */
}

Null_variable_info {
    u1 tag = ITEM_Null; /* 5 */
}

UninitializedThis_variable_info {
    u1 tag = ITEM_UninitializedThis; /* 6 */
}

Object_variable_info {
    u1 tag = ITEM_Object; /* 7 */
    u2 cpool_index;
}

Uninitialized_variable_info {
    u1 tag = ITEM_Uninitialized; /* 8 */
    u2 offset;
}

frame_type:ui

union stack_map_frame {
    same_frame;                                     // [0-63]
                                                    // 表示與前一個棧幀有着一樣的局部變量，且前一個操做棧爲空
                                                    // offset_delta = frame_type
    same_locals_1_stack_item_frame;                 // [64, 127] 
                                                    // 表示與前一個棧幀有着一樣的局部變量，且前一個操做棧有一個實體
                                                    // offset_delta = frame_type - 64
    same_locals_1_stack_item_frame_extended;        // 247
                                                    // 表示與前一個棧幀有着一樣的局部變量，且前一個操做棧有一個實體
                                                    // 與上一個不一樣的是，偏移量明確給出
    chop_frame;                                     // [248-250]
                                                    // 表示與前一個棧幀除了最後K個變量不一樣，其餘局部變量不變，且操做棧爲空
                                                    // K = 251 - frame_type
    same_frame_extended;                            // 251
                                                    // 表示與前一個棧幀有着一樣的局部變量，且操做棧爲空
    append_frame;                                   // [252-254]
                                                    // 表示與前一個棧幀除了K個變量不一樣，其餘局部變量不變，且操做棧爲空
                                                    // K = frame_type - 251
    full_frame;                                     // 255
                                                    //
}

same_frame {
    u1 frame_type = SAME; /* 0-63 */
}

same_locals_1_stack_item_frame {
    u1 frame_type = SAME_LOCALS_1_STACK_ITEM; /* 64-127 */
    verification_type_info stack[1];
}

same_locals_1_stack_item_frame_extended {
    u1 frame_type = SAME_LOCALS_1_STACK_ITEM_EXTENDED; /* 247 */
    u2 offset_delta;
    verification_type_info stack[1];
}

chop_frame {
    u1 frame_type = CHOP; /* 248-250 */
    u2 offset_delta;
}

same_frame_extended {
    u1 frame_type = SAME_FRAME_EXTENDED; /* 251 */
    u2 offset_delta;
}

append_frame {
    u1 frame_type = APPEND; /* 252-254 */
    u2 offset_delta;
    verification_type_info locals[frame_type - 251];        // locals[M+1] represents local variable N+1 / N+2（Long_variable_info or Double_variable_info）
}

full_frame {
    u1 frame_type = FULL_FRAME; /* 255 */
    u2 offset_delta;
    u2 number_of_locals;
    verification_type_info locals[number_of_locals];        // locals[M+1] represents local variable N+1 / N+2（Long_variable_info or Double_variable_info）
    u2 number_of_stack_items;
    verification_type_info stack[number_of_stack_items];    // stack[M+1] represents stack entry N+1 / N+2（Long_variable_info or Double_variable_info）
}

Exceptions

Exceptions_attribute {
    u2 attribute_name_index;                            // CONSTANT_Utf8_info -> constant_pool -> "Exceptions"
    u4 attribute_length;                                // excluding the initial six bytes 
    u2 number_of_exceptions;                            // the number of entries in the exception_index_table
    u2 exception_index_table[number_of_exceptions];     // CONSTANT_Class_info -> constant_pool
}

InnerClasses

InnerClasses_attribute {
    u2 attribute_name_index;                    // CONSTANT_Utf8_info -> constant_pool -> "InnerClasses"
    u4 attribute_length;                        // excluding the initial six bytes
    u2 number_of_classes;                       // the number of entries in the classes array
    { 
        u2 inner_class_info_index;              // CONSTANT_Class_info -> constant_pool
        u2 outer_class_info_index;              // zero => [anonymous class , local class ,top-level class or interface]
                                                // CONSTANT_Class_info - constant_pool
        u2 inner_name_index;                    // zero => anonymous class
                                                // anonymous class -> constant_pool
        u2 inner_class_access_flags;            // Table 4.7.6-A. Nested class access and property flags
    } classes[number_of_classes];               // 
}

Flag Name	Flag Name	Interpretation
ACC_PUBLIC	0x0001	`public`
ACC_PRIVATE	0x0002	`private`
ACC_PROTECTED	0x0004	`protected`
ACC_STATIC	0x0008	`static`
ACC_FINAL	0x0010	`final`
ACC_INTERFACE	0x0200	`interface`
ACC_ABSTRACT	0x0400	`abstract`
ACC_SYNTHETIC	0x1000	非源碼提供
ACC_ANNOTATION	0x2000	註解類型
ACC_ENUM	0x4000	枚舉類型

EnclosingMethod

EnclosingMethod_attribute {
    u2 attribute_name_index;        // CONSTANT_Utf8_info -> constant_pool -> "EnclosingMethod"
    u4 attribute_length;            // 4
    u2 class_index;                 // CONSTANT_Utf8_info -> constant_pool
    u2 method_index;                // zero => current class is not immediately enclosed by a method or constructor
                                    // CONSTANT_NameAndType_info -> constant_pool
}

Synthetic

Synthetic_attribute {
    u2 attribute_name_index;        // CONSTANT_Utf8_info -> constant_pool -> "Synthetic" 
    u4 attribute_length;            // must be zero
}

Signature

Signature_attribute {
    u2 attribute_name_index;        // CONSTANT_Utf8_info -> constant_pool -> "Signature" 
    u4 attribute_length;            // 2
    u2 signature_index;             // CONSTANT_Utf8_info -> constant_pool
}

MethodSignature:
[TypeParameters] ( {JavaTypeSignature} ) Result {ThrowsSignature}

SourceFile

SourceFile_attribute {
    u2 attribute_name_index;        // CONSTANT_Utf8_info -> constant_pool -> "SourceFile" 
    u4 attribute_length;            // 2
    u2 sourcefile_index;            // CONSTANT_Utf8_info -> constant_pool
}

SourceDebugExtension

SourceDebugExtension_attribute {
    u2 attribute_name_index;                // CONSTANT_Utf8_info -> constant_pool -> "SourceDebugExtension"
    u4 attribute_length;                    // excluding the initial six bytes
    u1 debug_extension[attribute_length];   // modified UTF-8 string
}

LineNumberTable

LineNumberTable_attribute {
    u2 attribute_name_index;                        // CONSTANT_Utf8_info -> constant_pool -> "LineNumberTable"
    u4 attribute_length;                            // excluding the initial six bytes
    u2 line_number_table_length;                    
    {
        u2 start_pc;                                // 
        u2 line_number;
    } line_number_table[line_number_table_length];
}

LocalVariableTable
- 能夠有多個，不要求順序

LocalVariableTable_attribute {
    u2 attribute_name_index;                                // CONSTANT_Utf8_info -> constant_pool -> "LocalVariableTable"
    u4 attribute_length;                                    // excluding the initial six bytes
    u2 local_variable_table_length;                         // the number of entries in the local_variable_table array
    { 
        u2 start_pc;                                        // 局部變量的做用域：[start_pc, start_pc + length)
        u2 length;
        u2 name_index;                                      // CONSTANT_Utf8_info -> constant_pool
        u2 descriptor_index;                                // CONSTANT_Utf8_info -> constant_pool
        u2 index;                                           // 槽位，遇到long / double 順延 + 1
    } local_variable_table[local_variable_table_length];
}

LocalVariableTypeTable
- 能夠有多個，不要求順序

LocalVariableTypeTable_attribute {
    u2 attribute_name_index;                                                // CONSTANT_Utf8_info -> constant_pool -> "LocalVariableTypeTable"
    u4 attribute_length;                                                    // excluding the initial six bytes
    u2 local_variable_type_table_length;
    { 
        u2 start_pc;                                                        //
        u2 length;
        u2 name_index;
        u2 signature_index;                                                 // CONSTANT_Utf8_info -> constant_pool
        u2 index;
    } local_variable_type_table[local_variable_type_table_length];
}

Deprecated

Deprecated_attribute {
    u2 attribute_name_index;        // CONSTANT_Utf8_info -> constant_pool -> "Deprecated"
    u4 attribute_length;            // must be zero
}

RuntimeVisibleAnnotations

RuntimeVisibleAnnotations_attribute {   
    u2 attribute_name_index;                        // CONSTANT_Utf8_info -> constant_pool -> "RuntimeVisibleAnnotations"
    u4 attribute_length;                            // excluding the initial six bytes
    u2 num_annotations;                             // 
    annotation annotations[num_annotations];        // annotation結構
}

annotation結構：debug

annotation {
    u2 type_index;                                      // CONSTANT_Utf8_info -> constant_pool -> descriptor
    u2 num_element_value_pairs;
    { 
        u2 element_name_index;                          // CONSTANT_Utf8_info -> constant_pool
        element_value value;                            // element_value結構
    } element_value_pairs[num_element_value_pairs];
}

element_value結構：code

element_value {
    u1 tag;                                         // single ASCII
                                                    // Table 4.7.16.1-A
    union {
        u2 const_value_index;                       // CONSTANT_Utf8_info -> constant_pool
        { 
            u2 type_name_index;                     // CONSTANT_Utf8_info -> constant_pool
            u2 const_name_index;
        } enum_const_value;
        u2 class_info_index;                        // CONSTANT_Utf8_info -> constant_pool -> descriptor
                                                    // BaseType character
                                                    // void : V
        annotation annotation_value;                // nested annotation
        { 
            u2 num_values;
            element_value values[num_values];
        } array_value;                              // element-value pair
    } value;
}

Table 4.7.16.1-A. Interpretation of tag values as typesorm

tag Item	Type	value Item	Constant Type
B	byte	const_value_index	CONSTANT_Integer
C	char	const_value_index	CONSTANT_Integer
D	double	const_value_index	CONSTANT_Double
F	float	const_value_index	CONSTANT_Float
I	int	const_value_index	CONSTANT_Integer
J	long	const_value_index	CONSTANT_Long
S	short	const_value_index	CONSTANT_Integer
Z	boolean	const_value_index	CONSTANT_Integer
s	String	const_value_index	CONSTANT_Utf8
e	Enum	type	enum_const_value
c	Class	class_info_index	Not applicable
@	Annotation	type	annotation_value
[	Array	type	array_value

RuntimeInvisibleAnnotations
- 相似RuntimeVisibleAnnotations

RuntimeInvisibleAnnotations_attribute {
    u2 attribute_name_index;
    u4 attribute_length;
    u2 num_annotations;
    annotation annotations[num_annotations];
}

RuntimeInvisibleParameterAnnotations

RuntimeInvisibleParameterAnnotations_attribute {
    u2 attribute_name_index;                        // CONSTANT_Utf8_info -> constant_pool -> "RuntimeInvisibleParameterAnnotations"
    u4 attribute_length;
    u1 num_parameters;
    { 
        u2 num_annotations;
        annotation annotations[num_annotations];
    } parameter_annotations[num_parameters];
}

RuntimeVisibleTypeAnnotations

RuntimeVisibleTypeAnnotations_attribute {
    u2 attribute_name_index;                        // CONSTANT_Utf8_info -> constant_pool -> "RuntimeVisibleTypeAnnotations"
    u4 attribute_length;
    u2 num_annotations;
    type_annotation annotations[num_annotations];   // type_annotation結構
}

type_annotation結構：接口

type_annotation {
    u1 target_type;                                         // Table 4.7.20-A 
                                                            // Table 4.7.20-B
                                                            // Table 4.7.20-C 
    union {
        type_parameter_target;
        supertype_target;
        type_parameter_bound_target;
        empty_target;
        formal_parameter_target;
        throws_target;
        localvar_target;
        catch_target;
        offset_target;
        type_argument_target;
    } target_info;                                          // target_info結構
    type_path target_path;                                  // type_path結構
    u2 type_index;
    u2 num_element_value_pairs;
    { 
        u2 element_name_index;
        element_value value;
    } element_value_pairs[num_element_value_pairs];
}

target_info結構：

type_parameter_target {
    u1 type_parameter_index;
}

supertype_target {
    u2 supertype_index;
}

type_parameter_bound_target {
    u1 type_parameter_index;
    u1 bound_index;
}

empty_target {
}

formal_parameter_target {
    u1 formal_parameter_index;
}

throws_target {
    u2 throws_type_index;
}

localvar_target {
    u2 table_length;
    {
        u2 start_pc;
        u2 length;
        u2 index;
    } table[table_length];
}

catch_target {
    u2 exception_table_index;
}

offset_target {
    u2 offset;
}

type_argument_target {
    u2 offset;
    u1 type_argument_index;
}

type_path結構：

type_path {
    u1 path_length;
    { 
        u1 type_path_kind;              // Table 4.7.20.2-A
        u1 type_argument_index;
    } path[path_length];
}

RuntimeInvisibleTypeAnnotations

RuntimeInvisibleTypeAnnotations_attribute {
    u2 attribute_name_index;
    u4 attribute_length;
    u2 num_annotations;
    type_annotation annotations[num_annotations];
}

AnnotationDefault

AnnotationDefault_attribute {
    u2 attribute_name_index;        // CONSTANT_Utf8_info -> constant_pool -> "AnnotationDefault"
    u4 attribute_length;            // excluding the initial six bytes
    element_value default_value;
}

BootstrapMethods

BootstrapMethods_attribute {
    u2 attribute_name_index;                                // CONSTANT_Utf8_info -> constant_pool -> "BootstrapMethods" 
    u4 attribute_length;                                    // excluding the initial six bytes
    u2 num_bootstrap_methods;
    { 
        u2 bootstrap_method_ref;                            // CONSTANT_MethodHandle_info
        u2 num_bootstrap_arguments;
        u2 bootstrap_arguments[num_bootstrap_arguments];    // constant_pool index
    } bootstrap_methods[num_bootstrap_methods];             // 
}

MethodParameters

MethodParameters_attribute {
    u2 attribute_name_index;            // CONSTANT_Utf8_info -> constant_pool -> "MethodParameters" 
    u4 attribute_length;                // excluding the initial six bytes
    u1 parameters_count;
    { 
        u2 name_index;                  // CONSTANT_Utf8_info -> constant_pool
        u2 access_flags;                // 0x0010 (ACC_FINAL)
                                        // 0x1000 (ACC_SYNTHETIC)
                                        // 0x8000 (ACC_MANDATED)
    } parameters[parameters_count];
}

Module

Module_attribute {
    u2 attribute_name_index;                    // CONSTANT_Utf8_info -> constant_pool -> "Module" 
    u4 attribute_length;                        // excluding the initial six bytes
    u2 module_name_index;                       // CONSTANT_Module_info -> constant_pool
    u2 module_flags;                            // 0x0020 (ACC_OPEN)
                                                // 0x1000 (ACC_SYNTHETIC)
                                                // 0x8000 (ACC_MANDATED)
    u2 module_version_index;                    // CONSTANT_Utf8_info -> constant_pool
    u2 requires_count;
    { 
        u2 requires_index;                      // CONSTANT_Module_info -> constant_pool
        u2 requires_flags;                      // 0x0020 (ACC_TRANSITIVE)
                                                // 0x0040 (ACC_STATIC_PHASE)
                                                // 0x1000 (ACC_SYNTHETIC)
                                                // 0x8000 (ACC_MANDATED)
        u2 requires_version_index;              // CONSTANT_Utf8_info -> constant_pool
    } requires[requires_count];
    u2 exports_count;
    { 
        u2 exports_index;                       // CONSTANT_Package_info -> constant_pool
        u2 exports_flags;                       // 0x1000 (ACC_SYNTHETIC)
                                                // 0x8000 (ACC_MANDATED)
        u2 exports_to_count;
        u2 exports_to_index[exports_to_count];  // CONSTANT_Module_info -> constant_pool
    } exports[exports_count];
    u2 opens_count;
    { 
        u2 opens_index;                         // CONSTANT_Package_info -> constant_pool
        u2 opens_flags;                         // 0x1000 (ACC_SYNTHETIC)
                                                // 0x8000 (ACC_MANDATED)
        u2 opens_to_count;
        u2 opens_to_index[opens_to_count];      // CONSTANT_Module_info -> constant_pool
    } opens[opens_count];
    u2 uses_count;
    u2 uses_index[uses_count];                  // CONSTANT_Class_info -> constant_pool
    u2 provides_count;
    { 
        u2 provides_index;                              // CONSTANT_Class_info -> constant_pool
        u2 provides_with_count;
        u2 provides_with_index[provides_with_count];    // CONSTANT_Class_info -> constant_pool
    } provides[provides_count];
}

ModulePackages

ModulePackages_attribute {
    u2 attribute_name_index;            // CONSTANT_Utf8_info -> constant_pool -> "ModulePackages" 
    u4 attribute_length;                // excluding the initial six bytes
    u2 package_count;
    u2 package_index[package_count];    // CONSTANT_Package_info -> constant_pool
}

ModuleMainClass

ModuleMainClass_attribute {
    u2 attribute_name_index;        // CONSTANT_Utf8_info -> constant_pool -> "ModuleMainClass" 
    u4 attribute_length;            // excluding the initial six bytes
    u2 main_class_index;            // CONSTANT_Class_info -> constant_pool
}

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每一个你不满意的现在，都有一个你没有努力的曾经。