| /* |
| * 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 org.apache.tomcat.util.bcel.classfile; |
| |
| import java.io.DataInputStream; |
| import java.io.DataOutputStream; |
| import java.io.IOException; |
| import java.io.Serializable; |
| |
| import org.apache.tomcat.util.bcel.Constants; |
| import org.apache.tomcat.util.bcel.util.BCELComparator; |
| |
| /** |
| * Abstract superclass for classes to represent the different constant types |
| * in the constant pool of a class file. The classes keep closely to |
| * the JVM specification. |
| * |
| * @version $Id: Constant.java,v 1.1 2011/06/28 21:08:23 rherrmann Exp $ |
| * @author <A HREF="mailto:m.dahm@gmx.de">M. Dahm</A> |
| */ |
| public abstract class Constant implements Cloneable, Serializable { |
| |
| private static final long serialVersionUID = 2827409182154809454L; |
| private static BCELComparator _cmp = new BCELComparator() { |
| |
| @Override |
| public boolean equals( Object o1, Object o2 ) { |
| Constant THIS = (Constant) o1; |
| Constant THAT = (Constant) o2; |
| return THIS.toString().equals(THAT.toString()); |
| } |
| |
| |
| @Override |
| public int hashCode( Object o ) { |
| Constant THIS = (Constant) o; |
| return THIS.toString().hashCode(); |
| } |
| }; |
| /* In fact this tag is redundant since we can distinguish different |
| * `Constant' objects by their type, i.e., via `instanceof'. In some |
| * places we will use the tag for switch()es anyway. |
| * |
| * First, we want match the specification as closely as possible. Second we |
| * need the tag as an index to select the corresponding class name from the |
| * `CONSTANT_NAMES' array. |
| */ |
| protected byte tag; |
| |
| |
| Constant(byte tag) { |
| this.tag = tag; |
| } |
| |
| |
| public abstract void dump( DataOutputStream file ) throws IOException; |
| |
| |
| /** |
| * @return Tag of constant, i.e., its type. No setTag() method to avoid |
| * confusion. |
| */ |
| public final byte getTag() { |
| return tag; |
| } |
| |
| |
| /** |
| * @return String representation. |
| */ |
| @Override |
| public String toString() { |
| return Constants.CONSTANT_NAMES[tag] + "[" + tag + "]"; |
| } |
| |
| |
| @Override |
| public Object clone() throws CloneNotSupportedException { |
| return super.clone(); |
| } |
| |
| |
| /** |
| * Read one constant from the given file, the type depends on a tag byte. |
| * |
| * @param file Input stream |
| * @return Constant object |
| */ |
| static final Constant readConstant( DataInputStream file ) throws IOException, |
| ClassFormatException { |
| byte b = file.readByte(); // Read tag byte |
| switch (b) { |
| case Constants.CONSTANT_Class: |
| return new ConstantClass(file); |
| case Constants.CONSTANT_Fieldref: |
| return new ConstantFieldref(file); |
| case Constants.CONSTANT_Methodref: |
| return new ConstantMethodref(file); |
| case Constants.CONSTANT_InterfaceMethodref: |
| return new ConstantInterfaceMethodref(file); |
| case Constants.CONSTANT_String: |
| return new ConstantString(file); |
| case Constants.CONSTANT_Integer: |
| return new ConstantInteger(file); |
| case Constants.CONSTANT_Float: |
| return new ConstantFloat(file); |
| case Constants.CONSTANT_Long: |
| return new ConstantLong(file); |
| case Constants.CONSTANT_Double: |
| return new ConstantDouble(file); |
| case Constants.CONSTANT_NameAndType: |
| return new ConstantNameAndType(file); |
| case Constants.CONSTANT_Utf8: |
| return new ConstantUtf8(file); |
| default: |
| throw new ClassFormatException("Invalid byte tag in constant pool: " + b); |
| } |
| } |
| |
| |
| /** |
| * Return value as defined by given BCELComparator strategy. |
| * By default two Constant objects are said to be equal when |
| * the result of toString() is equal. |
| * |
| * @see java.lang.Object#equals(java.lang.Object) |
| */ |
| @Override |
| public boolean equals( Object obj ) { |
| return _cmp.equals(this, obj); |
| } |
| |
| |
| /** |
| * Return value as defined by given BCELComparator strategy. |
| * By default return the hashcode of the result of toString(). |
| * |
| * @see java.lang.Object#hashCode() |
| */ |
| @Override |
| public int hashCode() { |
| return _cmp.hashCode(this); |
| } |
| } |