--- /dev/null	2019-03-13 11:16:31.764306451 +0800
+++ new/test/jdk/jfr/javaagent/JavaAgentBuilder.java	2019-09-27 13:25:33.209636982 +0800
@@ -0,0 +1,87 @@
+/*
+ * Copyright (c) 2019, 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.
+ */
+
+package jdk.test.lib.util;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.jar.Attributes;
+import java.util.jar.Manifest;
+
+import jdk.test.lib.Utils;
+import jdk.testlibrary.JarUtils;
+
+/**
+ * A builder for a common Java agent.
+ * Can be used directly from the jtreg test header to
+ * build a java agent before the test is executed.
+ *
+ * E.g.:
+ * @run driver jdk.test.lib.util.JavaAgentBuilder
+ *             jdk.jfr.javaagent.EventEmitterAgent EventEmitterAgent.jar
+ *
+ */
+public class JavaAgentBuilder {
+
+    /**
+     * Build a java agent jar file with a given agent class.
+     *
+     * @param args[0]    fully qualified name of an agent class
+     * @param args[1]    file name of the agent jar to be created
+     * @throws IOException
+     */
+    public static void main(String... args) throws IOException {
+        String agentClass = args[0];
+        String agentJar = args[1];
+        System.out.println("Building " + agentJar + " with agent class " + agentClass);
+        build(agentClass, agentJar);
+    }
+
+    /**
+     * Build a java agent jar file with a given agent class.
+     * The agent class will be added as both premain class and agent class.
+     *
+     * @param agentClass fully qualified name of an agent class
+     * @param agentJar   file name of the agent jar to be created
+     *                   the file will be placed in a current work directory
+     * @throws IOException
+     */
+    public static void build(String agentClass, String agentJar) throws IOException {
+        Manifest mf = new Manifest();
+        Attributes attrs = mf.getMainAttributes();
+        attrs.put(Attributes.Name.MANIFEST_VERSION, "1.0");
+        attrs.putValue("Premain-Class", agentClass);
+        attrs.putValue("Agent-Class", agentClass);
+
+        Path jarFile = Paths.get(".", agentJar);
+        String testClasses = Utils.TEST_CLASSES;
+        String agentPath = agentClass.replace(".", File.separator) + ".class";
+        Path agentFile = Paths.get(testClasses, agentPath);
+        Path dir = Paths.get(testClasses);
+        JarUtils.createJarFile(jarFile, mf, dir, agentFile);
+        System.out.println("Agent built:" + jarFile.toAbsolutePath());
+    }
+}