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/*
* Copyright (c) 2004, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
import java.io.*;
import java.nio.*;
import java.nio.channels.*;
public class CheckClassFileVersion {
static String get(String fn) throws IOException {
ByteBuffer bb = ByteBuffer.allocate(1024);
FileChannel fc = new FileInputStream(fn).getChannel();
try {
bb.clear();
if (fc.read(bb) < 0)
throw new IOException("Could not read any bytes");
bb.flip();
int minor = bb.getShort(4);
int major = bb.getShort(6);
return major + "." + minor;
} finally {
fc.close();
}
}
public static void main(String[] args) throws IOException {
String cfv = get(args[0]);
if (args.length == 1) {
System.out.println(cfv);
return;
}
if (!cfv.equals(args[1])) {
System.err.println("Class-file version mismatch: Expected "
+ args[1] + ", got " + cfv);
System.exit(1);
}
}
}
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