- /*
- * Copyright 2000,2002,2004 The Apache Software Foundation
- *
- * Licensed 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.tools.ant.taskdefs.optional.jlink;
-
- import java.io.DataInput;
- import java.io.DataInputStream;
- import java.io.IOException;
- import java.io.InputStream;
-
- /**
- * Reads just enough of a class file to determine the class' full name.
- *
- * <p>Extremely minimal constant pool implementation, mainly to support extracting
- * strings from a class file.
- */
- class ConstantPool {
-
- static final
- byte UTF8 = 1, UNUSED = 2, INTEGER = 3, FLOAT = 4, LONG = 5, DOUBLE = 6,
- CLASS = 7, STRING = 8, FIELDREF = 9, METHODREF = 10,
- INTERFACEMETHODREF = 11, NAMEANDTYPE = 12;
-
- byte[] types;
-
- Object[] values;
-
- ConstantPool(DataInput data) throws IOException {
- super();
-
- int count = data.readUnsignedShort();
- types = new byte [ count ];
- values = new Object [ count ];
- // read in all constant pool entries.
- for (int i = 1; i < count; i++) {
- byte type = data.readByte();
- types[i] = type;
- switch (type) {
- case UTF8 :
- values[i] = data.readUTF();
- break;
-
- case UNUSED :
- break;
-
- case INTEGER :
- values[i] = new Integer(data.readInt());
- break;
-
- case FLOAT :
- values[i] = new Float(data.readFloat());
- break;
-
- case LONG :
- values[i] = new Long(data.readLong());
- ++i;
- break;
-
- case DOUBLE :
- values[i] = new Double(data.readDouble());
- ++i;
- break;
-
- case CLASS :
- case STRING :
- values[i] = new Integer(data.readUnsignedShort());
- break;
-
- case FIELDREF :
- case METHODREF :
- case INTERFACEMETHODREF :
- case NAMEANDTYPE :
- values[i] = new Integer(data.readInt());
- break;
- }
- }
- }
- }
-
- /**
- * Provides a quick and dirty way to determine the true name of a class
- * given just an InputStream. Reads in just enough to perform this
- * minimal task only.
- */
- public class ClassNameReader extends Object {
-
- public static String getClassName(InputStream input) throws IOException {
- DataInputStream data = new DataInputStream(input);
- // verify this is a valid class file.
- int cookie = data.readInt();
- if (cookie != 0xCAFEBABE) {
- return null;
- }
- /* int version = */ data.readInt();
- // read the constant pool.
- ConstantPool constants = new ConstantPool(data);
- Object[] values = constants.values;
- // read access flags and class index.
- /* int accessFlags = */ data.readUnsignedShort();
- int classIndex = data.readUnsignedShort();
- Integer stringIndex = (Integer) values[classIndex];
- String className = (String) values[stringIndex.intValue()];
- return className;
- }
-
-
- }
-
-