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

import java.io.DataInput;
import java.io.DataOutputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

import com.sun.org.apache.bcel.internal.Const;

This class represents a reference to an unknown (i.e., application-specific) attribute of a class. It is instantiated from the Attribute.readAttribute(DataInput, ConstantPool) method. Applications that need to read in application-specific attributes should create an UnknownAttributeReader implementation and attach it via Attribute.addAttributeReader(String, UnknownAttributeReader).
See Also:
Version:$Id: Unknown.java 1749603 2016-06-21 20:50:19Z ggregory $
/** * This class represents a reference to an unknown (i.e., * application-specific) attribute of a class. It is instantiated from the * {@link Attribute#readAttribute(java.io.DataInput, ConstantPool)} method. * Applications that need to read in application-specific attributes should create an * {@link UnknownAttributeReader} implementation and attach it via * {@link Attribute#addAttributeReader(String, UnknownAttributeReader)}. * * @version $Id: Unknown.java 1749603 2016-06-21 20:50:19Z ggregory $ * @see Attribute * @see UnknownAttributeReader */
public final class Unknown extends Attribute { private byte[] bytes; private final String name; private static final Map<String, Unknown> 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() { final Unknown[] unknowns = new Unknown[unknown_attributes.size()]; unknown_attributes.values().toArray(unknowns); 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(final 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(final int name_index, final int length, final byte[] bytes, final ConstantPool constant_pool) { super(Const.ATTR_UNKNOWN, name_index, length, constant_pool); this.bytes = bytes; name = ((ConstantUtf8) constant_pool.getConstant(name_index, Const.CONSTANT_Utf8)) .getBytes(); unknown_attributes.put(name, this); }
Construct object from input stream.
Params:
  • name_index – Index in constant pool
  • length – Content length in bytes
  • input – Input stream
  • constant_pool – Array of constants
Throws:
/** * Construct object from input stream. * * @param name_index Index in constant pool * @param length Content length in bytes * @param input Input stream * @param constant_pool Array of constants * @throws IOException */
Unknown(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) throws IOException { this(name_index, length, (byte[]) null, constant_pool); if (length > 0) { bytes = new byte[length]; input.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 */
@Override public void accept( final 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 */
@Override public final void dump( final DataOutputStream file ) throws IOException { super.dump(file); if (super.getLength() > 0) { file.write(bytes, 0, super.getLength()); } }
Returns:data bytes.
/** * @return data bytes. */
public final byte[] getBytes() { return bytes; }
Returns:name of attribute.
/** * @return name of attribute. */
@Override public final String getName() { return name; }
Params:
  • bytes – the bytes to set
/** * @param bytes the bytes to set */
public final void setBytes( final byte[] bytes ) { this.bytes = bytes; }
Returns:String representation.
/** * @return String representation. */
@Override public final String toString() { if (super.getLength() == 0 || bytes == null) { return "(Unknown attribute " + name + ")"; } String hex; if (super.getLength() > 10) { final 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 */
@Override public Attribute copy( final ConstantPool _constant_pool ) { final Unknown c = (Unknown) clone(); if (bytes != null) { c.bytes = new byte[bytes.length]; System.arraycopy(bytes, 0, c.bytes, 0, bytes.length); } c.setConstantPool(_constant_pool); return c; } }