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 }