类 ClassReader

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

• SKIP_DEBUG

  public static final int SKIP_DEBUG

  A flag to skip the SourceFile, SourceDebugExtension, LocalVariableTable, LocalVariableTypeTable, LineNumberTable and MethodParameters attributes. If this flag is set these attributes are neither parsed nor visited (i.e. ClassVisitor.visitSource(java.lang.String, java.lang.String), MethodVisitor.visitLocalVariable(java.lang.String, java.lang.String, java.lang.String, org.springframework.asm.Label, org.springframework.asm.Label, int), MethodVisitor.visitLineNumber(int, org.springframework.asm.Label) and MethodVisitor.visitParameter(java.lang.String, int) are not called).

  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 (i.e. MethodVisitor.visitFrame(int, int, java.lang.Object[], int, java.lang.Object[]) is not called). This flag is useful when the ClassWriter.COMPUTE_FRAMES 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 (see Opcodes). 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.

  另请参阅:

  ClassVisitor.visit(int, int, String, String, String, String[])

• getClassName

  public String getClassName()

  Returns the internal name of the class (see Type.getInternalName()).

  返回:

  the internal class name.

  另请参阅:

  ClassVisitor.visit(int, int, String, String, String, String[])

• getSuperName

  public String getSuperName()

  Returns the internal of name of the super class (see Type.getInternalName()). For interfaces, the super class is Object.

  返回:

  the internal name of the super class, or null for Object class.

  另请参阅:

  ClassVisitor.visit(int, int, String, String, String, String[])

• getInterfaces

  public String[] getInterfaces()

  Returns the internal names of the implemented interfaces (see Type.getInternalName()).

  返回:

  the internal names of the directly implemented interfaces. Inherited implemented interfaces are not returned.

  另请参阅:

  ClassVisitor.visit(int, int, String, String, String, String[])

• accept

  public void accept​(ClassVisitor classVisitor,
                     int parsingOptions)

  Makes the given visitor visit the JVMS ClassFile structure passed to the constructor of this ClassReader.

  参数:

  classVisitor - the visitor that must visit this class.

  parsingOptions - the options to use to parse this class. One or more of SKIP_CODE, SKIP_DEBUG, SKIP_FRAMES or EXPAND_FRAMES.

• accept

  public void accept​(ClassVisitor classVisitor,
                     Attribute[] attributePrototypes,
                     int parsingOptions)

  Makes the given visitor visit the JVMS ClassFile structure passed to the constructor of this ClassReader.

  参数:

  classVisitor - the visitor that must visit this class.

  attributePrototypes - prototypes of the attributes that must be parsed during the visit of the class. Any attribute whose type is not equal to the type of one the prototypes will not be parsed: its byte array value will be passed unchanged to the ClassWriter. This may corrupt it if this value contains references to the constant pool, or has syntactic or semantic links with a class element that has been transformed by a class adapter between the reader and the writer.

  parsingOptions - the options to use to parse this class. One or more of SKIP_CODE, SKIP_DEBUG, SKIP_FRAMES or EXPAND_FRAMES.

• readLabel

  protected Label readLabel​(int bytecodeOffset,
                            Label[] labels)

  Returns the label corresponding to the given bytecode offset. The default implementation of this method creates a label for the given offset if it has not been already created.

  参数:

  bytecodeOffset - a bytecode offset in a method.

  labels - the already created labels, indexed by their offset. If a label already exists for bytecodeOffset this method must not create a new one. Otherwise it must store the new label in this array.

  返回:

  a non null Label, which must be equal to labels[bytecodeOffset].

• 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.

• readConst

  public Object readConst​(int constantPoolEntryIndex,
                          char[] charBuffer)

  Reads a numeric or string 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:

  constantPoolEntryIndex - the index of a CONSTANT_Integer, CONSTANT_Float, CONSTANT_Long, CONSTANT_Double, CONSTANT_Class, CONSTANT_String, CONSTANT_MethodType, CONSTANT_MethodHandle or CONSTANT_Dynamic entry in the class's constant pool.

  charBuffer - the buffer to be used to read strings. This buffer must be sufficiently large. It is not automatically resized.

  返回:

  the Integer, Float, Long, Double, String, Type, Handle or ConstantDynamic corresponding to the specified constant pool entry.