fieldinfo.java

已经移植好的java虚拟机

/*
 *  Copyright (c) 2000 Sun Microsystems, Inc., 901 San Antonio Road,
 *  Palo Alto, CA 94303, U.S.A.  All Rights Reserved.
 *
 *  Sun Microsystems, Inc. has intellectual property rights relating
 *  to the technology embodied in this software.  In particular, and
 *  without limitation, these intellectual property rights may include
 *  one or more U.S. patents, foreign patents, or pending
 *  applications.  Sun, Sun Microsystems, the Sun logo, Java, KJava,
 *  and all Sun-based and Java-based marks are trademarks or
 *  registered trademarks of Sun Microsystems, Inc.  in the United
 *  States and other countries.
 *
 *  This software is distributed under licenses restricting its use,
 *  copying, distribution, and decompilation.  No part of this
 *  software may be reproduced in any form by any means without prior
 *  written authorization of Sun and its licensors, if any.
 *
 *  FEDERAL ACQUISITIONS:  Commercial Software -- Government Users
 *  Subject to Standard License Terms and Conditions
 */
package kdp.classparser;

import kdp.classparser.attributes.*;
import kdp.classparser.constantpoolclasses.*;

import java.io.*;

/**
 * Encapsulates a field of a Java class file.
 *
 * @author 			Aaron Dietrich
 * @version			$Id: FieldInfo.java,v 1.1.1.1 2000/07/07 13:34:23 jrv Exp $
 *
 * Revision History
 *   $Log: FieldInfo.java,v $
 *   Revision 1.1.1.1  2000/07/07 13:34:23  jrv
 *   Initial import of kdp code
 *
 *   Revision 1.1.1.1  2000/05/31 19:14:47  ritsun
 *   Initial import of kvmdt to CVS
 *
 *   Revision 1.1  2000/04/25 00:36:43  ritsun
 *   Initial revision
 *
 */
public class FieldInfo
  {
   /** Access flag for a public class field */
   private static final int 	ACC_PUBLIC		= 0x0001;
   /** Access flag for a private class field */
   private static final int	ACC_PRIVATE		= 0x0002;
   /** Access flag for a protected class field */
   private static final int	ACC_PROTECTED		= 0x0004;
   /** Access flag for a static class field */
   private static final int	ACC_STATIC		= 0x0008;
   /** Access flag for a final class field */
   private static final int	ACC_FINAL			= 0x0010;
   /** Access flag for a volatile class field */
   private static final int	ACC_VOLATILE		= 0x0040;
   /** Access flag for a transient class field */
   private static final int	ACC_TRANSIENT		= 0x0080;

   /** access flags for this field */
   private int				accessFlags;
   /** index into constant pool with name of this field */
   private int				nameIndex;
   /** index into constant pool with type of this field */
   private int				descriptorIndex;
   /** number of attributes this field has */
   private int				attributesCount;
   /** array holding attributes of this field */
   private AttributeInfo		attributes[];

   /** the constant pool for this class */
   private ConstantPoolInfo[] constantPool;

   /**
    * Constructor.
    *
    * @param        iStream        input stream to read from
    * @param        constantPool   this classes constant pool
    *
    * @exception    IOException    just pass IO exceptions up
    */
   public FieldInfo (DataInputStream iStream,
                     final ConstantPoolInfo[] constantPool)	throws IOException
     {
      accessFlags = iStream.readUnsignedShort ();
      nameIndex = iStream.readUnsignedShort ();
      descriptorIndex = iStream.readUnsignedShort ();
      attributesCount = iStream.readUnsignedShort ();

      //allocate space for the attributes and read them in
      attributes = new AttributeInfo[attributesCount];

      for (int lcv = 0; lcv < attributesCount; ++lcv)
        attributes[lcv] = new AttributeInfo (iStream, constantPool);

      this.constantPool = constantPool;
     }

   /**
    * Returns the access permissions of this field in a text form.
    *
    * @return       String         access permissions of this field as text
    */
   public String getAccess ()
     {
      String        s = new String ("");

      if ((accessFlags & ACC_PUBLIC) > 0)
        s = s + "public ";

      if ((accessFlags & ACC_PRIVATE) > 0)
        s = s + "private ";

      if ((accessFlags & ACC_PROTECTED) > 0)
        s = s + "protected ";

      if ((accessFlags & ACC_STATIC) > 0)
        s = s + "static ";

      if ((accessFlags & ACC_FINAL) > 0)
        s = s + "final ";

      if ((accessFlags & ACC_VOLATILE) > 0)
        s = s + "volatile ";

      if ((accessFlags & ACC_TRANSIENT) > 0)
        s = s + "transient";

      if (s.length () == 0)
        s = "Not explicitly specified.";
        
      return s;
     }

   /**
    * Query the type of this field (int, float, etc)
    *
    * @return       String         full form of this field's type
    */
   public String getType ()
     {
      //look up the encoded type in the constant pool and parse it into
      //it's full form
      ConstantUtf8Info		utf8Info;

      utf8Info = (ConstantUtf8Info) constantPool[descriptorIndex];

      return (utf8Info.toString ());
     }

   /**
    * Query the name of this field.
    *
    * @return       String         the name of this field
    */
   public String getName ()
     {
      //look up in the constant pool and return the name of this field
      ConstantUtf8Info		utf8Info;

      utf8Info = (ConstantUtf8Info) constantPool[nameIndex];

      return utf8Info.toString ();
     }

   /**
    * Converts this field into a nice easy to read format for
    * displaying.
    *
    * @return       String         this field as a nice easy to read string
    */
   public String toString ()
     {
      String				s = new String ("");
      ConstantUtf8Info		utf8Info;

      //first determine what access flags are set for this field
      s = s + "Field:\n\tAccess Flags=\t";
      s = s + getAccess ();

      //get the name of this field
      s = s + "\n\tName=\t\t" + getName ();

      //get the type of this field
      s = s + "\n\tClass=\t\t" + getType ();

      //display all the attributes
      for (int lcv = 0; lcv < attributesCount; ++lcv)
        s = s + "\n\t" + attributes[lcv].toString ();

      return s;
     }
    public int getAccessFlags() {
	return accessFlags;
    }
  }