    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 represents the table of exceptions that are thrown by a
    028 * method. This attribute may be used once per method.  The name of
    029 * this class is <em>ExceptionTable</em> for historical reasons; The
    030 * Java Virtual Machine Specification, Second Edition defines this
    031 * attribute using the name <em>Exceptions</em> (which is inconsistent
    032 * with the other classes).
    033 *
    034 * @see     Code
    035 */
    036public final class ExceptionTable extends Attribute {
    037
    038    private int[] exception_index_table; // constant pool
    039
    040
    041    /**
    042     * Initialize from another object. Note that both objects use the same
    043     * references (shallow copy). Use copy() for a physical copy.
    044     */
    045    public ExceptionTable(final ExceptionTable c) {
    046        this(c.getNameIndex(), c.getLength(), c.getExceptionIndexTable(), c.getConstantPool());
    047    }
    048
    049
    050    /**
    051     * @param name_index Index in constant pool
    052     * @param length Content length in bytes
    053     * @param exception_index_table Table of indices in constant pool
    054     * @param constant_pool Array of constants
    055     */
    056    public ExceptionTable(final int name_index, final int length, final int[] exception_index_table,
    057            final ConstantPool constant_pool) {
    058        super(Const.ATTR_EXCEPTIONS, name_index, length, constant_pool);
    059        this.exception_index_table = exception_index_table != null ? exception_index_table : new int[0];
    060    }
    061
    062
    063    /**
    064     * Construct object from input stream.
    065     * @param name_index Index in constant pool
    066     * @param length Content length in bytes
    067     * @param input Input stream
    068     * @param constant_pool Array of constants
    069     * @throws IOException
    070     */
    071    ExceptionTable(final int name_index, final int length, final DataInput input, final ConstantPool constant_pool) throws IOException {
    072        this(name_index, length, (int[]) null, constant_pool);
    073        final int number_of_exceptions = input.readUnsignedShort();
    074        exception_index_table = new int[number_of_exceptions];
    075        for (int i = 0; i < number_of_exceptions; i++) {
    076            exception_index_table[i] = input.readUnsignedShort();
    077        }
    078    }
    079
    080
    081    /**
    082     * Called by objects that are traversing the nodes of the tree implicitely
    083     * defined by the contents of a Java class. I.e., the hierarchy of methods,
    084     * fields, attributes, etc. spawns a tree of objects.
    085     *
    086     * @param v Visitor object
    087     */
    088    @Override
    089    public void accept( final Visitor v ) {
    090        v.visitExceptionTable(this);
    091    }
    092
    093
    094    /**
    095     * Dump exceptions attribute to file stream in binary format.
    096     *
    097     * @param file Output file stream
    098     * @throws IOException
    099     */
    100    @Override
    101    public void dump( final DataOutputStream file ) throws IOException {
    102        super.dump(file);
    103        file.writeShort(exception_index_table.length);
    104        for (final int index : exception_index_table) {
    105            file.writeShort(index);
    106        }
    107    }
    108
    109
    110    /**
    111     * @return Array of indices into constant pool of thrown exceptions.
    112     */
    113    public int[] getExceptionIndexTable() {
    114        return exception_index_table;
    115    }
    116
    117
    118    /**
    119     * @return Length of exception table.
    120     */
    121    public int getNumberOfExceptions() {
    122        return exception_index_table == null ? 0 : exception_index_table.length;
    123    }
    124
    125
    126    /**
    127     * @return class names of thrown exceptions
    128     */
    129    public String[] getExceptionNames() {
    130        final String[] names = new String[exception_index_table.length];
    131        for (int i = 0; i < exception_index_table.length; i++) {
    132            names[i] = super.getConstantPool().getConstantString(exception_index_table[i],
    133                    Const.CONSTANT_Class).replace('/', '.');
    134        }
    135        return names;
    136    }
    137
    138
    139    /**
    140     * @param exception_index_table the list of exception indexes
    141     * Also redefines number_of_exceptions according to table length.
    142     */
    143    public void setExceptionIndexTable( final int[] exception_index_table ) {
    144        this.exception_index_table = exception_index_table != null ? exception_index_table : new int[0];
    145    }
    146
    147
    148    /**
    149     * @return String representation, i.e., a list of thrown exceptions.
    150     */
    151    @Override
    152    public String toString() {
    153        final StringBuilder buf = new StringBuilder();
    154        String str;
    155        buf.append("Exceptions: ");
    156        for (int i = 0; i < exception_index_table.length; i++) {
    157            str = super.getConstantPool().getConstantString(exception_index_table[i], Const.CONSTANT_Class);
    158            buf.append(Utility.compactClassName(str, false));
    159            if (i < exception_index_table.length - 1) {
    160                buf.append(", ");
    161            }
    162        }
    163        return buf.toString();
    164    }
    165
    166
    167    /**
    168     * @return deep copy of this attribute
    169     */
    170    @Override
    171    public Attribute copy( final ConstantPool _constant_pool ) {
    172        final ExceptionTable c = (ExceptionTable) clone();
    173        if (exception_index_table != null) {
    174            c.exception_index_table = new int[exception_index_table.length];
    175            System.arraycopy(exception_index_table, 0, c.exception_index_table, 0,
    176                    exception_index_table.length);
    177        }
    178        c.setConstantPool(_constant_pool);
    179        return c;
    180    }
    181}