Agent.java

/*
 * Copyright (c) 2016, 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.PrintStream;
import java.lang.instrument.*;
import java.lang.reflect.Field;

/**
  * @test
  * @bug 8160950
  * @summary test for custom system class loader
  *
  * @run build App Agent CustomLoader
  * @run shell ../MakeJAR3.sh Agent 'Can-Retransform-Classes: true'
  * @run main/othervm -javaagent:Agent.jar -Djava.system.class.loader=CustomLoader App
  */

public class Agent {
    private static PrintStream err = System.err;
    private static PrintStream out = System.out;
    public  static boolean failed = false;

    public static void premain(String agentArgs, Instrumentation instrumentation) {
        ClassLoader myClassLoader = Agent.class.getClassLoader();
        out.println("Agent: started; myClassLoader: " + myClassLoader);
        try {
            Field fld = myClassLoader.getClass().getField("agentClassLoader");
            fld.set(myClassLoader.getClass(), myClassLoader);
        } catch (Exception ex) {
            failed = true;
            ex.printStackTrace();
        }
        out.println("Agent: finished");
   }
}