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Apache CXF example source code file (JDKBugHacks.java)

This example Apache CXF source code file (JDKBugHacks.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Apache CXF tags/keywords

class, classloader, classloader, documentbuilderfactory, image, imageio, jdkbughacks, jdkbughacks, method, net, network, parser, reflection, throwable, throwable, url, url, urlconnection

The Apache CXF JDKBugHacks.java source code

/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you 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.cxf.common.logging;

import java.lang.reflect.Method;
import java.net.URL;
import java.net.URLConnection;

import javax.imageio.ImageIO;
import javax.xml.parsers.DocumentBuilderFactory;

/**
 * This is called from LogUtils as LogUtils is almost always one of the VERY
 * first classes loaded in CXF so we can try and register to hacks/workarounds
 * for various bugs in the JDK.
 * 
 * Much of this is taken from work the Tomcat folks have done to find
 * places where memory leaks and jars are locked and such.
 * See:
 * http://svn.apache.org/viewvc/tomcat/trunk/java/org/apache/catalina/
 * core/JreMemoryLeakPreventionListener.java
 * 
 */
final class JDKBugHacks {
    private JDKBugHacks() {
        //not constructed
    }
    
    public static void doHacks() {
        ClassLoader orig = Thread.currentThread().getContextClassLoader();
        try {
            //set to the topmost non-null so things that grab the context classloader
            //won't get our classloader.
            ClassLoader ncl = orig;
            while (ncl.getParent() != null) {
                ncl = ncl.getParent();
            }
            Thread.currentThread().setContextClassLoader(ncl);
            
            try {
                //Trigger a call to sun.awt.AppContext.getAppContext()
                ImageIO.getCacheDirectory();
            } catch (Throwable t) {
                //ignore
            }
            try {
                // Several components end up opening JarURLConnections without first
                // disabling caching. This effectively locks the file.
                // JAXB does this and thus affects us pretty badly.
                // Doesn't matter that this JAR doesn't exist - just as long as
                // the URL is well-formed
                URL url = new URL("jar:file://dummy.jar!/");
                URLConnection uConn = url.openConnection();
                uConn.setDefaultUseCaches(false);
            } catch (Throwable e) {
                //ignore
            }
            try {
                //DocumentBuilderFactory seems to SOMETIMES pin the classloader
                DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
                factory.newDocumentBuilder();
            } catch (Throwable e) {
                //ignore
            }
            // Several components end up calling:
            // sun.misc.GC.requestLatency(long)
            //
            // Those libraries / components known to trigger memory leaks due to
            // eventual calls to requestLatency(long) are:
            // - javax.management.remote.rmi.RMIConnectorServer.start()
            try {
                Class<?> clazz = Class.forName("sun.misc.GC");
                Method method = clazz.getDeclaredMethod("requestLatency",
                        new Class[] {Long.TYPE});
                method.invoke(null, Long.valueOf(3600000));
            } catch (Throwable e) {
                //ignore
            }
        } finally {
            Thread.currentThread().setContextClassLoader(orig);
        }
        
    }

}

Other Apache CXF examples (source code examples)

Here is a short list of links related to this Apache CXF JDKBugHacks.java source code file:

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