1 /*
   2  * Copyright (c) 2007, 2008, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 package com.sun.tools.classfile;
  27 
  28 import java.io.BufferedInputStream;
  29 import java.io.ByteArrayInputStream;
  30 import java.io.DataInputStream;
  31 import java.io.IOException;
  32 import java.io.InputStream;
  33 import java.util.Objects;
  34 
  35 /**
  36  *  <p><b>This is NOT part of any supported API.
  37  *  If you write code that depends on this, you do so at your own risk.
  38  *  This code and its internal interfaces are subject to change or
  39  *  deletion without notice.</b>
  40  */
  41 public class ClassReader {
  42     ClassReader(ClassFile classFile, InputStream in, Attribute.Factory attributeFactory) throws IOException {
  43         this.classFile = Objects.requireNonNull(classFile);
  44         this.attributeFactory = Objects.requireNonNull(attributeFactory);
  45         this.in = new DataInputStream(new BufferedInputStream(in));
  46     }
  47 
  48     ClassFile getClassFile() {
  49         return classFile;
  50     }
  51 
  52     ConstantPool getConstantPool() {
  53         return classFile.constant_pool;
  54     }
  55 
  56     public Attribute readAttribute() throws IOException {
  57         int name_index = readUnsignedShort();
  58         int length = readInt();
  59         byte[] data = new byte[length];
  60         readFully(data);
  61 
  62         DataInputStream prev = in;
  63         in = new DataInputStream(new ByteArrayInputStream(data));
  64         try {
  65             return attributeFactory.createAttribute(this, name_index, data);
  66         } finally {
  67             in = prev;
  68         }
  69     }
  70 
  71     public void readFully(byte[] b) throws IOException {
  72         in.readFully(b);
  73     }
  74 
  75     public int readUnsignedByte() throws IOException {
  76         return in.readUnsignedByte();
  77     }
  78 
  79     public int readUnsignedShort() throws IOException {
  80         return in.readUnsignedShort();
  81     }
  82 
  83     public int readInt() throws IOException {
  84         return in.readInt();
  85     }
  86 
  87     public long readLong() throws IOException {
  88         return in.readLong();
  89     }
  90 
  91     public float readFloat() throws IOException {
  92         return in.readFloat();
  93     }
  94 
  95     public double readDouble() throws IOException {
  96         return in.readDouble();
  97     }
  98 
  99     public String readUTF() throws IOException {
 100         return in.readUTF();
 101     }
 102 
 103     private DataInputStream in;
 104     private ClassFile classFile;
 105     private Attribute.Factory attributeFactory;
 106 }