ClassReader (nacos-common 2.4.2 2.4.2 API)

java.lang.Object
- com.alibaba.nacos.common.packagescan.classreading.ClassReader

```
public class ClassReader
extends Object
```
Copy from ASM, with less modifications A parser to make a visit a ClassFile structure, as defined in the Java Virtual Machine Specification (JVMS). This class parses the ClassFile content and calls the appropriate visit methods of a given ClassVisitor for each field, method and bytecode instruction encountered.

作者:

Eric Bruneton, Eugene Kuleshov

另请参阅:

JVMS 4

字段概要

字段
限定符和类型	字段和说明
`byte[]`	`b` 已过时。 Use `readByte(int)` and the other read methods instead. This field will eventually be deleted.
`static int`	`EXPAND_FRAMES` A flag to expand the stack map frames.
`int`	`header` The offset in bytes of the ClassFile's access_flags field.
`static int`	`SKIP_CODE` A flag to skip the Code attributes.
`static int`	`SKIP_DEBUG` A flag to skip the SourceFile.
`static int`	`SKIP_FRAMES` A flag to skip the StackMap and StackMapTable attributes.
`static int`	`V19`

构造器概要

构造器
构造器和说明
`ClassReader(byte[] classFile)` Constructs a new `ClassReader` object.
`ClassReader(byte[] classFileBuffer, int classFileOffset, int classFileLength)` Constructs a new `ClassReader` object.
`ClassReader(InputStream inputStream)` Constructs a new `ClassReader` object.
`ClassReader(String className)` Constructs a new `ClassReader` object.

方法概要

所有方法实例方法具体方法
限定符和类型	方法和说明
`int`	`getAccess()` Returns the class's access flags .
`String`	`getClassName()` the internal class name.
`String[]`	`getInterfaces()` the internal names of the directly implemented interfaces.
`int`	`getItem(int constantPoolEntryIndex)` Returns the start offset in this `ClassReader` of a JVMS 'cp_info' structure (i.e. a constant pool entry), plus one.
`int`	`getItemCount()` Returns the number of entries in the class's constant pool table.
`int`	`getMaxStringLength()` Returns a conservative estimate of the maximum length of the strings contained in the class's constant pool table.
`String`	`getSuperName()`
`int`	`readByte(int offset)` Reads a byte value in this `ClassReader`.
`String`	`readClass(int offset, char[] charBuffer)` Reads a CONSTANT_Class constant pool entry in this `ClassReader`.
`int`	`readInt(int offset)` Reads a signed int value in this `ClassReader`.
`long`	`readLong(int offset)` Reads a signed long value in this `ClassReader`.
`String`	`readModule(int offset, char[] charBuffer)` Reads a CONSTANT_Module constant pool entry in this `ClassReader`.
`String`	`readPackage(int offset, char[] charBuffer)` Reads a CONSTANT_Package constant pool entry in this `ClassReader`.
`short`	`readShort(int offset)` Reads a signed short value in this `ClassReader`.
`int`	`readUnsignedShort(int offset)` Reads an unsigned short value in this `ClassReader`.
`String`	`readUtf8(int offset, char[] charBuffer)` Reads a CONSTANT_Utf8 constant pool entry in this `ClassReader`.

从类继承的方法 java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- 字段详细资料
  - SKIP_CODE
```
public static final int SKIP_CODE
```
    A flag to skip the Code attributes. If this flag is set the Code attributes are neither parsed nor visited.
    
    另请参阅:
    
    常量字段值
  - V19
```
public static final int V19
```
    另请参阅:
    
    常量字段值
  - SKIP_DEBUG
```
public static final int SKIP_DEBUG
```
    A flag to skip the SourceFile.
    
    另请参阅:
    
    常量字段值
  - SKIP_FRAMES
```
public static final int SKIP_FRAMES
```
    A flag to skip the StackMap and StackMapTable attributes. If this flag is set these attributes are neither parsed nor visited is not called). This flag is useful when the option is used: it avoids visiting frames that will be ignored and recomputed from scratch.
    
    另请参阅:
    
    常量字段值
  - EXPAND_FRAMES
```
public static final int EXPAND_FRAMES
```
    A flag to expand the stack map frames. By default stack map frames are visited in their original format (i.e. "expanded" for classes whose version is less than V1_6, and "compressed" for the other classes). If this flag is set, stack map frames are always visited in expanded format (this option adds a decompression/compression step in ClassReader and ClassWriter which degrades performance quite a lot).
    
    另请参阅:
    
    常量字段值
  - b
```
@Deprecated
public final byte[] b
```
    已过时。 Use readByte(int) and the other read methods instead. This field will eventually be deleted.
    
    A byte array containing the JVMS ClassFile structure to be parsed.
  - header
```
public final int header
```
    The offset in bytes of the ClassFile's access_flags field.
- 构造器详细资料
  - ClassReader
```
public ClassReader(byte[] classFile)
```
    Constructs a new ClassReader object.
    
    参数:
    
    classFile - the JVMS ClassFile structure to be read.
  - ClassReader
```
public ClassReader(byte[] classFileBuffer,
                   int classFileOffset,
                   int classFileLength)
```
    Constructs a new ClassReader object.
    
    参数:
    
    classFileBuffer - a byte array containing the JVMS ClassFile structure to be read.
    
    classFileOffset - the offset in byteBuffer of the first byte of the ClassFile to be read.
    
    classFileLength - the length in bytes of the ClassFile to be read.
  - ClassReader
```
public ClassReader(InputStream inputStream)
            throws IOException
```
    Constructs a new ClassReader object.
    
    参数:
    
    inputStream - an input stream of the JVMS ClassFile structure to be read. This input stream must contain nothing more than the ClassFile structure itself. It is read from its current position to its end.
    
    抛出:
    
    IOException - if a problem occurs during reading.
  - ClassReader
```
public ClassReader(String className)
            throws IOException
```
    Constructs a new ClassReader object.
    
    参数:
    
    className - the fully qualified name of the class to be read. The ClassFile structure is retrieved with the current class loader's ClassLoader.getSystemResourceAsStream(java.lang.String).
    
    抛出:
    
    IOException - if an exception occurs during reading.
- 方法详细资料
  - getAccess
```
public int getAccess()
```
    Returns the class's access flags . This value may not reflect Deprecated and Synthetic flags when bytecode is before 1.5 and those flags are represented by attributes.
    
    返回:
    
    the class access flags.
  - getClassName
```
public String getClassName()
```
    the internal class name.
  - getSuperName
```
public String getSuperName()
```
  - getInterfaces
```
public String[] getInterfaces()
```
    the internal names of the directly implemented interfaces. Inherited implemented interfaces are not returned.
  - getItemCount
```
public int getItemCount()
```
    Returns the number of entries in the class's constant pool table.
    
    返回:
    
    the number of entries in the class's constant pool table.
  - getItem
```
public int getItem(int constantPoolEntryIndex)
```
    Returns the start offset in this ClassReader of a JVMS 'cp_info' structure (i.e. a constant pool entry), plus one. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
    
    参数:
    
    constantPoolEntryIndex - the index a constant pool entry in the class's constant pool table.
    
    返回:
    
    the start offset in this ClassReader of the corresponding JVMS 'cp_info' structure, plus one.
  - getMaxStringLength
```
public int getMaxStringLength()
```
    Returns a conservative estimate of the maximum length of the strings contained in the class's constant pool table.
    
    返回:
    
    a conservative estimate of the maximum length of the strings contained in the class's constant pool table.
  - readByte
```
public int readByte(int offset)
```
    Reads a byte value in this ClassReader. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
    
    参数:
    
    offset - the start offset of the value to be read in this ClassReader.
    
    返回:
    
    the read value.
  - readUnsignedShort
```
public int readUnsignedShort(int offset)
```
    Reads an unsigned short value in this ClassReader. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
    
    参数:
    
    offset - the start index of the value to be read in this ClassReader.
    
    返回:
    
    the read value.
  - readShort
```
public short readShort(int offset)
```
    Reads a signed short value in this ClassReader. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
    
    参数:
    
    offset - the start offset of the value to be read in this ClassReader.
    
    返回:
    
    the read value.
  - readInt
```
public int readInt(int offset)
```
    Reads a signed int value in this ClassReader. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
    
    参数:
    
    offset - the start offset of the value to be read in this ClassReader.
    
    返回:
    
    the read value.
  - readLong
```
public long readLong(int offset)
```
    Reads a signed long value in this ClassReader. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
    
    参数:
    
    offset - the start offset of the value to be read in this ClassReader.
    
    返回:
    
    the read value.
  - readUtf8
```
public String readUtf8(int offset,
                       char[] charBuffer)
```
    Reads a CONSTANT_Utf8 constant pool entry in this ClassReader. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
    
    参数:
    
    offset - the start offset of an unsigned short value in this ClassReader, whose value is the index of a CONSTANT_Utf8 entry in the class's constant pool table.
    
    charBuffer - the buffer to be used to read the string. This buffer must be sufficiently large. It is not automatically resized.
    
    返回:
    
    the String corresponding to the specified CONSTANT_Utf8 entry.
  - readClass
```
public String readClass(int offset,
                        char[] charBuffer)
```
    Reads a CONSTANT_Class constant pool entry in this ClassReader. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
    
    参数:
    
    offset - the start offset of an unsigned short value in this ClassReader, whose value is the index of a CONSTANT_Class entry in class's constant pool table.
    
    charBuffer - the buffer to be used to read the item. This buffer must be sufficiently large. It is not automatically resized.
    
    返回:
    
    the String corresponding to the specified CONSTANT_Class entry.
  - readModule
```
public String readModule(int offset,
                         char[] charBuffer)
```
    Reads a CONSTANT_Module constant pool entry in this ClassReader. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
    
    参数:
    
    offset - the start offset of an unsigned short value in this ClassReader, whose value is the index of a CONSTANT_Module entry in class's constant pool table.
    
    charBuffer - the buffer to be used to read the item. This buffer must be sufficiently large. It is not automatically resized.
    
    返回:
    
    the String corresponding to the specified CONSTANT_Module entry.
  - readPackage
```
public String readPackage(int offset,
                          char[] charBuffer)
```
    Reads a CONSTANT_Package constant pool entry in this ClassReader. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
    
    参数:
    
    offset - the start offset of an unsigned short value in this ClassReader, whose value is the index of a CONSTANT_Package entry in class's constant pool table.
    
    charBuffer - the buffer to be used to read the item. This buffer must be sufficiently large. It is not automatically resized.
    
    返回:
    
    the String corresponding to the specified CONSTANT_Package entry.

类 ClassReader

字段概要

构造器概要

方法概要

从类继承的方法 java.lang.Object

字段详细资料

SKIP_CODE

V19

SKIP_DEBUG

SKIP_FRAMES

EXPAND_FRAMES

b

header

构造器详细资料

ClassReader

ClassReader

ClassReader

ClassReader

方法详细资料

getAccess

getClassName

getSuperName

getInterfaces

getItemCount

getItem

getMaxStringLength

readByte

readUnsignedShort

readShort

readInt

readLong

readUtf8

readClass

readModule

readPackage