1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one or more 3 * contributor license agreements. See the NOTICE file distributed with 4 * this work for additional information regarding copyright ownership. 5 * The ASF licenses this file to You under the Apache License, Version 2.0 6 * (the "License"); you may not use this file except in compliance with 7 * the License. You may obtain a copy of the License at 8 * 9 * http://www.apache.org/licenses/LICENSE-2.0 10 * 11 * Unless required by applicable law or agreed to in writing, software 12 * distributed under the License is distributed on an "AS IS" BASIS, 13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 14 * See the License for the specific language governing permissions and 15 * limitations under the License. 16 * 17 */ 18 package org.apache.bcel.classfile; 19 20 import java.io.DataInput; 21 import java.io.DataOutputStream; 22 import java.io.IOException; 23 24 import org.apache.bcel.Const; 25 26 /** 27 * This class is derived from the abstract {@link Constant} 28 * and represents a reference to a (external) class. 29 * 30 * @see Constant 31 */ 32 public final class ConstantClass extends Constant implements ConstantObject { 33 34 private int name_index; // Identical to ConstantString except for the name 35 36 37 /** 38 * Initialize from another object. 39 */ ConstantClass(final ConstantClass c)40 public ConstantClass(final ConstantClass c) { 41 this(c.getNameIndex()); 42 } 43 44 45 /** 46 * Constructs an instance from file data. 47 * 48 * @param dataInput Input stream 49 * @throws IOException if an I/O error occurs reading from the given {@code dataInput}. 50 */ ConstantClass(final DataInput dataInput)51 ConstantClass(final DataInput dataInput) throws IOException { 52 this(dataInput.readUnsignedShort()); 53 } 54 55 56 /** 57 * @param name_index Name index in constant pool. Should refer to a 58 * ConstantUtf8. 59 */ ConstantClass(final int name_index)60 public ConstantClass(final int name_index) { 61 super(Const.CONSTANT_Class); 62 this.name_index = name_index; 63 } 64 65 66 /** 67 * Called by objects that are traversing the nodes of the tree implicitely 68 * defined by the contents of a Java class. I.e., the hierarchy of methods, 69 * fields, attributes, etc. spawns a tree of objects. 70 * 71 * @param v Visitor object 72 */ 73 @Override accept( final Visitor v )74 public void accept( final Visitor v ) { 75 v.visitConstantClass(this); 76 } 77 78 79 /** 80 * Dumps constant class to file stream in binary format. 81 * 82 * @param file Output file stream 83 * @throws IOException if an I/O error occurs writing to the DataOutputStream. 84 */ 85 @Override dump( final DataOutputStream file )86 public final void dump( final DataOutputStream file ) throws IOException { 87 file.writeByte(super.getTag()); 88 file.writeShort(name_index); 89 } 90 91 92 /** 93 * @return Name index in constant pool of class name. 94 */ getNameIndex()95 public final int getNameIndex() { 96 return name_index; 97 } 98 99 100 /** 101 * @param name_index the name index in the constant pool of this Constant Class 102 */ setNameIndex( final int name_index )103 public final void setNameIndex( final int name_index ) { 104 this.name_index = name_index; 105 } 106 107 108 /** @return String object 109 */ 110 @Override getConstantValue( final ConstantPool cp )111 public Object getConstantValue( final ConstantPool cp ) { 112 final Constant c = cp.getConstant(name_index, Const.CONSTANT_Utf8); 113 return ((ConstantUtf8) c).getBytes(); 114 } 115 116 117 /** @return dereferenced string 118 */ getBytes( final ConstantPool cp )119 public String getBytes( final ConstantPool cp ) { 120 return (String) getConstantValue(cp); 121 } 122 123 124 /** 125 * @return String representation. 126 */ 127 @Override toString()128 public final String toString() { 129 return super.toString() + "(name_index = " + name_index + ")"; 130 } 131 } 132