程序包 org.beetl.ow2.asm

类 ClassReader

java.lang.Object
org.beetl.ow2.asm.ClassReader
public class ClassReader extends Object
A Java class parser to make a ClassVisitor visit an existing class. This class parses a byte array conforming to the Java class file format and calls the appropriate visit methods of a given class visitor for each field, method and bytecode instruction encountered.
作者:
Eric Bruneton, Eugene Kuleshov

  • 字段详细资料

    • SKIP_CODE

      public static final int SKIP_CODE
      Flag to skip method code. If this class is set CODE attribute won't be visited. This can be used, for example, to retrieve annotations for methods and method parameters.
      另请参阅:

    • SKIP_DEBUG

      public static final int SKIP_DEBUG
      Flag to skip the debug information in the class. If this flag is set the debug information of the class is not visited, i.e. the visitLocalVariable and visitLineNumber methods will not be called.
      另请参阅:

    • SKIP_FRAMES

      public static final int SKIP_FRAMES
      Flag to skip the stack map frames in the class. If this flag is set the stack map frames of the class is not visited, i.e. the visitFrame method will not be 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 in the class writer.
      另请参阅:

    • EXPAND_FRAMES

      public static final int EXPAND_FRAMES
      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/recompression step in ClassReader and ClassWriter which degrades performances quite a lot).
      另请参阅:

    • b

      public final byte[] b
      The class to be parsed. The content of this array must not be modified. This field is intended for Attribute sub classes, and is normally not needed by class generators or adapters.

  • 构造器详细资料

    • ClassReader

      public ClassReader(byte[] b)
      Constructs a new ClassReader object.
      参数:
      b - the bytecode of the class to be read.

    • ClassReader

      public ClassReader(byte[] b, int off, int len)
      Constructs a new ClassReader object.
      参数:
      b - the bytecode of the class to be read.
      off - the start offset of the class data.
      len - the length of the class data.

    • ClassReader

      public ClassReader(InputStream is) throws IOException
      Constructs a new ClassReader object.
      参数:
      is - an input stream from which to read the class.
      抛出:
      IOException - if a problem occurs during reading.

    • ClassReader

      public ClassReader(String name) throws IOException
      Constructs a new ClassReader object.
      参数:
      name - the binary qualified className of the class to be read.
      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:

    • getClassName

      public String getClassName()
      Returns the internal className of the class (see getInternalName).
      返回:
      the internal class className
      另请参阅:

    • getSuperName

      public String getSuperName()
      Returns the internal of className of the super class (see getInternalName). For interfaces, the super class is Object.
      返回:
      the internal className of super class, or null for Object class.
      另请参阅:

    • getInterfaces

      public String[] getInterfaces()
      Returns the internal names of the class's interfaces (see getInternalName).
      返回:
      the array of internal names for all implemented interfaces or null.
      另请参阅:

    • accept

      public void accept(ClassVisitor classVisitor, int flags)
      Makes the given visitor visit the Java class of this ClassReader . This class is the one specified in the constructor (see ClassReader).
      参数:
      classVisitor - the visitor that must visit this class.
      flags - option flags that can be used to modify the default behavior of this class. See SKIP_DEBUG, EXPAND_FRAMES , SKIP_FRAMES, SKIP_CODE.

    • accept

      public void accept(ClassVisitor classVisitor, Attribute[] attrs, int flags)
      Makes the given visitor visit the Java class of this ClassReader. This class is the one specified in the constructor (see ClassReader).
      参数:
      classVisitor - the visitor that must visit this class.
      attrs - 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.
      flags - option flags that can be used to modify the default behavior of this class. See SKIP_DEBUG, EXPAND_FRAMES , SKIP_FRAMES, SKIP_CODE.

    • readLabel

      protected Label readLabel(int offset, Label[] labels)
      Returns the label corresponding to the given offset. The default implementation of this method creates a label for the given offset if it has not been already created.
      参数:
      offset - a bytecode offset in a method.
      labels - the already created labels, indexed by their offset. If a label already exists for offset 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[offset].

    • getItemCount

      public int getItemCount()
      Returns the number of constant pool items in b.
      返回:
      the number of constant pool items in b.

    • getItem

      public int getItem(int item)
      Returns the start index of the constant pool item in b, plus one. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      item - the index a constant pool item.
      返回:
      the start index of the constant pool item in b, plus one.

    • getMaxStringLength

      public int getMaxStringLength()
      Returns the maximum length of the strings contained in the constant pool of the class.
      返回:
      the maximum length of the strings contained in the constant pool of the class.

    • readByte

      public int readByte(int index)
      Reads a byte value in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      index - the start index of the value to be read in b.
      返回:
      the read value.

    • readUnsignedShort

      public int readUnsignedShort(int index)
      Reads an unsigned short value in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      index - the start index of the value to be read in b.
      返回:
      the read value.

    • readShort

      public short readShort(int index)
      Reads a signed short value in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      index - the start index of the value to be read in b.
      返回:
      the read value.

    • readInt

      public int readInt(int index)
      Reads a signed int value in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      index - the start index of the value to be read in b.
      返回:
      the read value.

    • readLong

      public long readLong(int index)
      Reads a signed long value in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      index - the start index of the value to be read in b.
      返回:
      the read value.

    • readUTF8

      public String readUTF8(int index, char[] buf)
      Reads an UTF8 string constant pool item in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      index - the start index of an unsigned short value in b, whose value is the index of an UTF8 constant pool item.
      buf - 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 UTF8 item.

    • readClass

      public String readClass(int index, char[] buf)
      Reads a class constant pool item in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      index - the start index of an unsigned short value in b, whose value is the index of a class constant pool item.
      buf - 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 class item.

    • readConst

      public Object readConst(int item, char[] buf)
      Reads a numeric or string constant pool item in b. This method is intended for Attribute sub classes, and is normally not needed by class generators or adapters.
      参数:
      item - the index of a constant pool item.
      buf - buffer to be used to read the item. This buffer must be sufficiently large. It is not automatically resized.
      返回:
      the Integer, Float, Long, Double, String, Type or Handle corresponding to the given constant pool item.