constantclass.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.*;

/** 
 * This class is derived from the abstract 
 * <A HREF="de.fub.bytecode.classfile.Constant.html">Constant</A> class 
 * and represents a reference to a (external) class.
 *
 * @version $Id: ConstantClass.java,v 1.4 2001/08/08 14:01:11 dahm Exp $
 * @author  <A HREF="http://www.berlin.de/~markus.dahm/">M. Dahm</A>
 * @see     Constant
 */
public final class ConstantClass extends Constant implements ConstantObject {
  private int name_index; // Identical to ConstantString except for the name

  /**
   * Initialize from another object.
   */
  public ConstantClass(ConstantClass c) {
    this(c.getNameIndex());
  }    

  /**
   * Initialize instance from file data.
   *
   * @param file Input stream
   * @throw IOException
   */
  ConstantClass(DataInputStream file) throws IOException
  {    
    this(file.readUnsignedShort());
  }    

  /**
   * @param name_index Name index in constant pool
   */
  public ConstantClass(int name_index) {
    super(Constants.CONSTANT_Class);
    this.name_index = name_index;
  }    

  /**
   * Called by objects that are traversing the nodes of the tree implicitely
   * defined by the contents of a Java class. I.e., the hierarchy of methods,
   * fields, attributes, etc. spawns a tree of objects.
   *
   * @param v Visitor object
   */
  public void accept(Visitor v) {
    v.visitConstantClass(this);
  }    

  /** 
   * Dump constant class to file stream in binary format.
   *
   * @param file Output file stream
   * @throw IOException
   */ 
  public final void dump(DataOutputStream file) throws IOException
  {
    file.writeByte(tag);
    file.writeShort(name_index);
  }    

  /**
   * @return Name index in constant pool of class name.
   */  
  public final int getNameIndex() { return name_index; }    

  /**
   * @param name_index.
   */
  public final void setNameIndex(int name_index) {
    this.name_index = name_index;
  }    


  /** @return String object
   */
  public Object getConstantValue(ConstantPool cp) {
    Constant c = cp.getConstant(name_index, Constants.CONSTANT_Utf8);
    return ((ConstantUtf8)c).getBytes();
  }

  /** @return dereferenced string
   */
  public String getBytes(ConstantPool cp) {
    return (String)getConstantValue(cp);
  }

  /**
   * @return String representation.
   */
  public final String toString() {
    return super.toString() + "(name_index = " + name_index + ")";
  }
}