https://openjdk.java.net/ 
/*
 * reserved comment block
 * DO NOT REMOVE OR ALTER!
 */
/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.sun.org.apache.bcel.internal.classfile;


import com.sun.org.apache.bcel.internal.Constants;
import java.io.*;
import java.util.*;


This class represents a reference to an unknown (i.e.,
application-specific) attribute of a class.  It is instantiated from the
Attribute.readAttribute() method.  Applications that need to
read in application-specific attributes should create an AttributeReader implementation and
attach it via Attribute.addAttributeReader.

Author: M. Dahm
See Also:
/**
 * This class represents a reference to an unknown (i.e.,
 * application-specific) attribute of a class.  It is instantiated from the
 * <em>Attribute.readAttribute()</em> method.  Applications that need to
 * read in application-specific attributes should create an <a
 * href="./AttributeReader.html">AttributeReader</a> implementation and
 * attach it via <a
 * href="./Attribute.html#addAttributeReader(java.lang.String,
 * com.sun.org.apache.bcel.internal.classfile.AttributeReader)">Attribute.addAttributeReader</a>.

 *
 * @see com.sun.org.apache.bcel.internal.classfile.Attribute
 * @see com.sun.org.apache.bcel.internal.classfile.AttributeReader
 * @author  <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A>
 */
public final class Unknown extends Attribute {
  private byte[] bytes;
  private String name;

  private static HashMap unknown_attributes = new HashMap();

  
Returns:array of unknown attributes, but just one for each kind.
/** @return array of unknown attributes, but just one for each kind.
   */
  static Unknown[] getUnknownAttributes() {
    Unknown[] unknowns = new Unknown[unknown_attributes.size()];
    Iterator  entries  = unknown_attributes.values().iterator();

    for(int i=0; entries.hasNext(); i++)
      unknowns[i] = (Unknown)entries.next();

    unknown_attributes.clear();
    return unknowns;
  }

  
Initialize from another object. Note that both objects use the same
references (shallow copy). Use clone() for a physical copy.

/**
   * Initialize from another object. Note that both objects use the same
   * references (shallow copy). Use clone() for a physical copy.
   */
  public Unknown(Unknown c) {
    this(c.getNameIndex(), c.getLength(), c.getBytes(), c.getConstantPool());
  }

  
Create a non-standard attribute.

Params:
  • name_index – Index in constant pool
  • length – Content length in bytes
  • bytes – Attribute contents
  • constant_pool – Array of constants
/**
   * Create a non-standard attribute.
   *
   * @param name_index Index in constant pool
   * @param length Content length in bytes
   * @param bytes Attribute contents
   * @param constant_pool Array of constants
   */
  public Unknown(int name_index, int length, byte[] bytes,
                 ConstantPool constant_pool)
  {
    super(Constants.ATTR_UNKNOWN, name_index, length, constant_pool);
    this.bytes = bytes;

    name = ((ConstantUtf8)constant_pool.getConstant(name_index,
                                                    Constants.CONSTANT_Utf8)).getBytes();
    unknown_attributes.put(name, this);
  }

  
Construct object from file stream.

Params:
  • name_index – Index in constant pool
  • length – Content length in bytes
  • file – Input stream
  • constant_pool – Array of constants
Throws:
/**
   * Construct object from file stream.
   * @param name_index Index in constant pool
   * @param length Content length in bytes
   * @param file Input stream
   * @param constant_pool Array of constants
   * @throws IOException
   */
  Unknown(int name_index, int length, DataInputStream file,
          ConstantPool constant_pool)
       throws IOException
  {
    this(name_index, length, (byte [])null, constant_pool);

    if(length > 0) {
      bytes = new byte[length];
      file.readFully(bytes);
    }
  }

  
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.

Params:
  • v – Visitor object
/**
   * 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.visitUnknown(this);
  }
  
Dump unknown bytes to file stream.

Params:
  • file – Output file stream
Throws:
/**
   * Dump unknown bytes to file stream.
   *
   * @param file Output file stream
   * @throws IOException
   */
  public final void dump(DataOutputStream file) throws IOException
  {
    super.dump(file);
    if(length > 0)
      file.write(bytes, 0, length);
  }
  
Returns:data bytes.
/**
   * @return data bytes.
   */
  public final byte[] getBytes() { return bytes; }

  
Returns:name of attribute.
/**
   * @return name of attribute.
   */
  public final String getName() { return name; }

  
@parambytes.
/**
   * @param bytes.
   */
  public final void setBytes(byte[] bytes) {
    this.bytes = bytes;
  }

  
Returns:String representation.
/**
   * @return String representation.
   */
  public final String toString() {
    if(length == 0 || bytes == null)
      return "(Unknown attribute " + name + ")";

    String hex;
    if(length > 10) {
      byte[] tmp = new byte[10];
      System.arraycopy(bytes, 0, tmp, 0, 10);
      hex = Utility.toHexString(tmp) + "... (truncated)";
    }
    else
      hex = Utility.toHexString(bytes);

    return "(Unknown attribute " + name + ": " + hex + ")";
  }

  
Returns:deep copy of this attribute
/**
   * @return deep copy of this attribute
   */
  public Attribute copy(ConstantPool constant_pool) {
    Unknown c = (Unknown)clone();

    if(bytes != null)
      c.bytes = (byte[])bytes.clone();

    c.constant_pool = constant_pool;
    return c;
  }
}