fieldormethod.java

代码是一个分类器的实现,其中使用了部分weka的源代码。可以将项目导入eclipse运行

package de.fub.bytecode.classfile;
import  de.fub.bytecode.Constants;
import java.io.*;

/** 
 * Abstract super class for fields and methods.
 *
 * @version $Id: FieldOrMethod.java,v 1.4 2001/06/11 11:38:08 dahm Exp $
 * @author  <A HREF="http://www.berlin.de/~markus.dahm/">M. Dahm</A>
 */
public abstract class FieldOrMethod extends AccessFlags implements Cloneable, Node {
  protected int          name_index;      // Points to field name in constant pool 
  protected int          signature_index; // Points to encoded signature
  protected int          attributes_count;// No. of attributes
  protected Attribute[]  attributes;      // Collection of attributes
  protected ConstantPool constant_pool;

  FieldOrMethod() {}
  
  /**
   * Initialize from another object. Note that both objects use the same
   * references (shallow copy). Use clone() for a physical copy.
   */
  protected FieldOrMethod(FieldOrMethod c) {
    this(c.getAccessFlags(), c.getNameIndex(), c.getSignatureIndex(),
	 c.getAttributes(), c.getConstantPool());
  }

  /**
   * Construct object from file stream.
   * @param file Input stream
   * @throw IOException
   * @throw ClassFormatError
   */
  protected FieldOrMethod(DataInputStream file, ConstantPool constant_pool)
    throws IOException, ClassFormatError
  {
    this(file.readUnsignedShort(), file.readUnsignedShort(),
	 file.readUnsignedShort(), null, constant_pool);

    attributes_count = file.readUnsignedShort();
    attributes       = new Attribute[attributes_count];
    for(int i=0; i < attributes_count; i++)
      attributes[i] = Attribute.readAttribute(file, constant_pool);
  }

  /**
   * @param access_flags Access rights of method
   * @param name_index Points to field name in constant pool
   * @param signature_index Points to encoded signature
   * @param attributes Collection of attributes
   * @param constant_pool Array of constants
   */
  protected FieldOrMethod(int access_flags, int name_index, int signature_index,
			  Attribute[] attributes, ConstantPool constant_pool)
  {
    this.access_flags    = access_flags;
    this.name_index      = name_index;
    this.signature_index = signature_index;
    this.constant_pool   = constant_pool;

    setAttributes(attributes);
  }

  /**
   * Dump object to file stream on binary format.
   *
   * @param file Output file stream
   * @throw IOException
   */ 
  public final void dump(DataOutputStream file) throws IOException
  {
    file.writeShort(access_flags);
    file.writeShort(name_index);
    file.writeShort(signature_index);
    file.writeShort(attributes_count);

    for(int i=0; i < attributes_count; i++)
      attributes[i].dump(file);
  }

  /**
   * @return Collection of object attributes.
   */   
  public final Attribute[] getAttributes() { return attributes; }

  /**
   * @param attributes Collection of object attributes.
   */
  public final void setAttributes(Attribute[] attributes) {
    this.attributes  = attributes;
    attributes_count = (attributes == null)? 0 : attributes.length;
  }

  /**
   * @return Constant pool used by this object.
   */   
  public final ConstantPool getConstantPool() { return constant_pool; }

  /**
   * @param constant_pool Constant pool to be used for this object.
   */   
  public final void setConstantPool(ConstantPool constant_pool) {
    this.constant_pool = constant_pool;
  }

  /**
   * @return Index in constant pool of object's name.
   */   
  public final int getNameIndex() { return name_index; }

  /**
   * @param name_index Index in constant pool of object's name.
   */
  public final void setNameIndex(int name_index) {
    this.name_index = name_index;
  }

  /**
   * @return Index in constant pool of field signature.
   */   
  public final int getSignatureIndex() { return signature_index; }    

  /**
   * @param signature_index Index in constant pool of field signature.
   */
  public final void setSignatureIndex(int signature_index) {
    this.signature_index = signature_index;
  }

  /**
   * @return Name of object, i.e., method name or field name
   */   
  public final String getName() {
    ConstantUtf8  c;
    c = (ConstantUtf8)constant_pool.getConstant(name_index, 
						Constants.CONSTANT_Utf8);
    return c.getBytes();
  }

  /**
   * @return String representation of object's type signature (java style)
   */   
  public final String getSignature() {
    ConstantUtf8  c;
    c = (ConstantUtf8)constant_pool.getConstant(signature_index,
						Constants.CONSTANT_Utf8);
    return c.getBytes();
  }

  /**
   * @return deep copy of this field
   */
  protected FieldOrMethod copy_(ConstantPool constant_pool) {
    FieldOrMethod c = null;

    try {
      c = (FieldOrMethod)clone();
    } catch(CloneNotSupportedException e) {}

    c.constant_pool    = constant_pool;
    c.attributes       = new Attribute[attributes_count];

    for(int i=0; i < attributes_count; i++)
      c.attributes[i] = attributes[i].copy(constant_pool);

    return c;
  }
}