001/* 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 * 017 */ 018package org.apache.bcel.classfile; 019 020import java.io.DataInput; 021import java.io.DataOutputStream; 022import java.io.IOException; 023 024import org.apache.bcel.Const; 025 026/** 027 * This class is derived from the abstract {@link Constant} 028 * and represents a reference to a package. 029 * 030 * <p>Note: Early access Java 9 support- currently subject to change</p> 031 * 032 * @see Constant 033 * @since 6.1 034 */ 035public final class ConstantPackage extends Constant implements ConstantObject { 036 037 private int name_index; 038 039 040 /** 041 * Initialize from another object. 042 */ 043 public ConstantPackage(final ConstantPackage c) { 044 this(c.getNameIndex()); 045 } 046 047 048 /** 049 * Initialize instance from file data. 050 * 051 * @param file Input stream 052 * @throws IOException 053 */ 054 ConstantPackage(final DataInput file) throws IOException { 055 this(file.readUnsignedShort()); 056 } 057 058 059 /** 060 * @param name_index Name index in constant pool. Should refer to a 061 * ConstantUtf8. 062 */ 063 public ConstantPackage(final int name_index) { 064 super(Const.CONSTANT_Package); 065 this.name_index = name_index; 066 } 067 068 069 /** 070 * Called by objects that are traversing the nodes of the tree implicitly 071 * defined by the contents of a Java class. I.e., the hierarchy of methods, 072 * fields, attributes, etc. spawns a tree of objects. 073 * 074 * @param v Visitor object 075 */ 076 @Override 077 public void accept( final Visitor v ) { 078 v.visitConstantPackage(this); 079 } 080 081 082 /** 083 * Dump constant package to file stream in binary format. 084 * 085 * @param file Output file stream 086 * @throws IOException 087 */ 088 @Override 089 public void dump( final DataOutputStream file ) throws IOException { 090 file.writeByte(super.getTag()); 091 file.writeShort(name_index); 092 } 093 094 095 /** 096 * @return Name index in constant pool of package name. 097 */ 098 public int getNameIndex() { 099 return name_index; 100 } 101 102 103 /** 104 * @param name_index the name index in the constant pool of this Constant Package 105 */ 106 public void setNameIndex( final int name_index ) { 107 this.name_index = name_index; 108 } 109 110 111 /** @return String object 112 */ 113 @Override 114 public Object getConstantValue( final ConstantPool cp ) { 115 final Constant c = cp.getConstant(name_index, Const.CONSTANT_Utf8); 116 return ((ConstantUtf8) c).getBytes(); 117 } 118 119 120 /** @return dereferenced string 121 */ 122 public String getBytes( final ConstantPool cp ) { 123 return (String) getConstantValue(cp); 124 } 125 126 127 /** 128 * @return String representation. 129 */ 130 @Override 131 public String toString() { 132 return super.toString() + "(name_index = " + name_index + ")"; 133 } 134}