View Javadoc
1 package org.apache.bcel.classfile; 2 3 /* ==================================================================== 4 * The Apache Software License, Version 1.1 5 * 6 * Copyright (c) 2001 The Apache Software Foundation. All rights 7 * reserved. 8 * 9 * Redistribution and use in source and binary forms, with or without 10 * modification, are permitted provided that the following conditions 11 * are met: 12 * 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 16 * 2. Redistributions in binary form must reproduce the above copyright 17 * notice, this list of conditions and the following disclaimer in 18 * the documentation and/or other materials provided with the 19 * distribution. 20 * 21 * 3. The end-user documentation included with the redistribution, 22 * if any, must include the following acknowledgment: 23 * "This product includes software developed by the 24 * Apache Software Foundation (http://www.apache.org/)." 25 * Alternately, this acknowledgment may appear in the software itself, 26 * if and wherever such third-party acknowledgments normally appear. 27 * 28 * 4. The names "Apache" and "Apache Software Foundation" and 29 * "Apache BCEL" must not be used to endorse or promote products 30 * derived from this software without prior written permission. For 31 * written permission, please contact apache@apache.org. 32 * 33 * 5. Products derived from this software may not be called "Apache", 34 * "Apache BCEL", nor may "Apache" appear in their name, without 35 * prior written permission of the Apache Software Foundation. 36 * 37 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED 38 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 39 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 40 * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR 41 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 42 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 43 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF 44 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 45 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 46 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 47 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 48 * SUCH DAMAGE. 49 * ==================================================================== 50 * 51 * This software consists of voluntary contributions made by many 52 * individuals on behalf of the Apache Software Foundation. For more 53 * information on the Apache Software Foundation, please see 54 * <http://www.apache.org/>;. 55 */ 56 57 import org.apache.bcel.Constants; 58 import java.io.*; 59 60 /*** 61 * Abstract superclass for classes to represent the different constant types 62 * in the constant pool of a class file. The classes keep closely to 63 * the JVM specification. 64 * 65 * @version $Id: Constant.java,v 1.3 2002/07/11 19:39:04 mdahm Exp $ 66 * @author <A HREF="mailto:markus.dahm@berlin.de">M. Dahm</A> 67 */ 68 public abstract class Constant implements Cloneable, Node, Serializable { 69 /* In fact this tag is redundant since we can distinguish different 70 * `Constant' objects by their type, i.e., via `instanceof'. In some 71 * places we will use the tag for switch()es anyway. 72 * 73 * First, we want match the specification as closely as possible. Second we 74 * need the tag as an index to select the corresponding class name from the 75 * `CONSTANT_NAMES' array. 76 */ 77 protected byte tag; 78 79 Constant(byte tag) { this.tag = tag; } 80 81 /*** 82 * Called by objects that are traversing the nodes of the tree implicitely 83 * defined by the contents of a Java class. I.e., the hierarchy of methods, 84 * fields, attributes, etc. spawns a tree of objects. 85 * 86 * @param v Visitor object 87 */ 88 public abstract void accept(Visitor v); 89 90 public abstract void dump(DataOutputStream file) throws IOException; 91 92 /*** 93 * @return Tag of constant, i.e., its type. No setTag() method to avoid 94 * confusion. 95 */ 96 public final byte getTag() { return tag; } 97 98 /*** 99 * @return String representation. 100 */ 101 public String toString() { 102 return Constants.CONSTANT_NAMES[tag] + "[" + tag + "]"; 103 } 104 105 /*** 106 * @return deep copy of this constant 107 */ 108 public Constant copy() { 109 try { 110 return (Constant)super.clone(); 111 } catch(CloneNotSupportedException e) {} 112 113 return null; 114 } 115 116 public Object clone() throws CloneNotSupportedException { 117 return super.clone(); 118 } 119 120 /*** 121 * Read one constant from the given file, the type depends on a tag byte. 122 * 123 * @param file Input stream 124 * @return Constant object 125 */ 126 static final Constant readConstant(DataInputStream file) 127 throws IOException, ClassFormatException 128 { 129 byte b = file.readByte(); // Read tag byte 130 131 switch(b) { 132 case Constants.CONSTANT_Class: return new ConstantClass(file); 133 case Constants.CONSTANT_Fieldref: return new ConstantFieldref(file); 134 case Constants.CONSTANT_Methodref: return new ConstantMethodref(file); 135 case Constants.CONSTANT_InterfaceMethodref: return new 136 ConstantInterfaceMethodref(file); 137 case Constants.CONSTANT_String: return new ConstantString(file); 138 case Constants.CONSTANT_Integer: return new ConstantInteger(file); 139 case Constants.CONSTANT_Float: return new ConstantFloat(file); 140 case Constants.CONSTANT_Long: return new ConstantLong(file); 141 case Constants.CONSTANT_Double: return new ConstantDouble(file); 142 case Constants.CONSTANT_NameAndType: return new ConstantNameAndType(file); 143 case Constants.CONSTANT_Utf8: return new ConstantUtf8(file); 144 default: 145 throw new ClassFormatException("Invalid byte tag in constant pool: " + b); 146 } 147 } 148 }

This page was automatically generated by Maven