現在時刻を偽装するJava Agent

Java
作ってみたはいいが、実行するとJDK/JREの使用許諾に違反するようです。
現時点では著作権は放棄していませんしライセンスは未整理です。
javassist に依存しています。
matobaa
2011/8/12 0:07
タグ：
タグはありません
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package org.ocharake.matobaa.utlib;
import java.io.ByteArrayInputStream;
import java.lang.instrument.ClassFileTransformer;
import java.lang.instrument.IllegalClassFormatException;
import java.lang.instrument.Instrumentation;
import java.security.ProtectionDomain;
import java.util.Calendar;
import java.util.Date;
import javassist.ClassPool;
import javassist.CtBehavior;
import javassist.CtClass;
public class NowDateMockAgent {
    /**
     * An entry point for insert NowDateMockAgent functionality to
     * java.util.Date and java.util.GregorianCalendar.
     * 
     * This method will be invoked before enter the main mathod with VM's
     * runtime argument as follows: -javaagent:nowdateagent.jar
     * 
     * @param agentArgs
     *            ignored. don't care.
     * @param instrumentation
     *            ignored. don't care.
     */
    public static void premain(String agentArgs, Instrumentation instrumentation) {
        instrumentation.addTransformer(new DateTransformer());
    }
    private static final class DateTransformer implements ClassFileTransformer {
        static String expected = "Long.parseLong(System.getProperty(\""
                + NowDateMockAgent.class.getCanonicalName() + "\"));";
        public byte[] transform(ClassLoader loader, String className,
                Class<?> void1, ProtectionDomain void2, byte[] classfileBuffer)
                throws IllegalClassFormatException {
            try {
                // insert "time=0" at end of
                // GregorianCalengar.<init>(TimeZone,Locale)
                if (className.equals("java/util/GregorianCalendar")) {
                    ClassPool pool = ClassPool.getDefault();
                    ByteArrayInputStream stream = new ByteArrayInputStream(
                            classfileBuffer);
                    CtClass targetType = pool.makeClass(stream);
                    CtClass[] paramTypes = pool.get(new String[] {
                            "java/util/TimeZone", "java/util/Locale" });
                    CtBehavior constructor = targetType
                            .getDeclaredConstructor(paramTypes);
                    constructor.insertAfter("time = " + expected);
                    return targetType.toBytecode();
                }
                // insert "fastTime=0" at end of java.util.Date.<init>()
                if (className.equals("java/util/Date")) {
                    ClassPool pool = ClassPool.getDefault();
                    ByteArrayInputStream stream = new ByteArrayInputStream(
                            classfileBuffer);
                    CtClass targetType = pool.makeClass(stream);
                    targetType.getDeclaredConstructor(new CtClass[0])
                            .insertAfter("fastTime = " + expected);
                    return targetType.toBytecode();
                }
            } catch (Exception initCause) {
                IllegalClassFormatException e = new IllegalClassFormatException();
                e.initCause(initCause);
                throw e;
            }
            return null;
        }
    }
    static {
        System.setProperty(NowDateMockAgent.class.getCanonicalName(), "0");
    }
    /**
     * Set the date value you expected.
     * 
     * @param dateExpected
     *            expected date as long
     */
    public static void setExpected(long dateExpected) {
        System.setProperty(NowDateMockAgent.class.getCanonicalName(),
                Long.toString(dateExpected));
    }
    /**
     * Set the date value you expected
     * 
     * @param dateExpected
     *            expected date as java.util.Date
     */
    public static void setExpected(Date dateExpected) {
        setExpected(dateExpected.getTime());
    }
    /**
     * Set the date value you expected
     * 
     * @param dateExpected
     *            expected date as java.util.Calendar
     */
    public static void setExpected(Calendar dateExpected) {
        setExpected(dateExpected.getTime().getTime());
    }
}
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