org.apache.log4j.helpers.Loader Maven / Gradle / Ivy
/*
* 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.log4j.helpers;
import java.io.InterruptedIOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.URL;
/**
* Load resources (or images) from various sources.
*
* @author Ceki Gülcü
*/
public class Loader {
static final String TSTR = "Caught Exception while in Loader.getResource. This may be innocuous.";
// Assume we're not using Java 1.1
static private boolean java1 = false;
static private boolean ignoreTCL = false;
static {
String prop = OptionConverter.getSystemProperty("java.version", null);
if (prop != null) {
int i = prop.indexOf('.');
if (prop.charAt(0) == '1' && i != -1) {
if (prop.charAt(i + 1) == '1')
java1 = true;
}
}
String ignoreTCLProp = OptionConverter.getSystemProperty("log4j.ignoreTCL", null);
if (ignoreTCLProp != null) {
ignoreTCL = OptionConverter.toBoolean(ignoreTCLProp, true);
}
}
/**
* Get a resource by delegating to getResource(String).
*
* @param resource resource name
* @param clazz class, ignored.
*
* @return URL to resource or null.
*
* @deprecated as of 1.2.
*/
public static URL getResource(String resource, Class clazz) {
return getResource(resource);
}
/**
* This method will search for resource in different
* places. The search order is as follows:
*
*
*
* - Search for
resource using the thread context
* class loader under Java2. If that fails, search for
* resource using the class loader that loaded this
* class (Loader). Under JDK 1.1, only the the class
* loader that loaded this class (Loader) is used.
*
* - Try one last time with
*
ClassLoader.getSystemResource(resource), that is is
* using the system class loader in JDK 1.2 and virtual machine's
* built-in class loader in JDK 1.1.
*
*
*/
static public URL getResource(String resource) {
ClassLoader classLoader = null;
URL url = null;
try {
if (!java1 && !ignoreTCL) {
classLoader = getTCL();
if (classLoader != null) {
LogLog.debug("Trying to find [" + resource + "] using context classloader "
+ classLoader + ".");
url = classLoader.getResource(resource);
if (url != null) {
return url;
}
}
}
// We could not find resource. Ler us now try with the
// classloader that loaded this class.
classLoader = Loader.class.getClassLoader();
if (classLoader != null) {
LogLog.debug("Trying to find [" + resource + "] using " + classLoader
+ " class loader.");
url = classLoader.getResource(resource);
if (url != null) {
return url;
}
}
} catch (IllegalAccessException t) {
LogLog.warn(TSTR, t);
} catch (InvocationTargetException t) {
if (t.getTargetException() instanceof InterruptedException
|| t.getTargetException() instanceof InterruptedIOException) {
Thread.currentThread().interrupt();
}
LogLog.warn(TSTR, t);
} catch (Throwable t) {
//
// can't be InterruptedException or InterruptedIOException
// since not declared, must be error or RuntimeError.
LogLog.warn(TSTR, t);
}
// Last ditch attempt: get the resource from the class path. It
// may be the case that clazz was loaded by the Extentsion class
// loader which the parent of the system class loader. Hence the
// code below.
LogLog.debug("Trying to find [" + resource +
"] using ClassLoader.getSystemResource().");
return ClassLoader.getSystemResource(resource);
}
/**
* Are we running under JDK 1.x?
*/
public
static boolean isJava1() {
return java1;
}
/**
* Get the Thread Context Loader which is a JDK 1.2 feature. If we
* are running under JDK 1.1 or anything else goes wrong the method
* returns null.
*/
private static ClassLoader getTCL() throws IllegalAccessException,
InvocationTargetException {
// Are we running on a JDK 1.2 or later system?
Method method = null;
try {
method = Thread.class.getMethod("getContextClassLoader", null);
} catch (NoSuchMethodException e) {
// We are running on JDK 1.1
return null;
}
return (ClassLoader) method.invoke(Thread.currentThread(), null);
}
/**
* If running under JDK 1.2 load the specified class using the
* Thread contextClassLoader if that
* fails try Class.forname. Under JDK 1.1 only Class.forName is
* used.
*/
static public Class loadClass(String clazz) throws ClassNotFoundException {
// Just call Class.forName(clazz) if we are running under JDK 1.1
// or if we are instructed to ignore the TCL.
if (java1 || ignoreTCL) {
return Class.forName(clazz);
} else {
try {
return getTCL().loadClass(clazz);
}
// we reached here because tcl was null or because of a
// security exception, or because clazz could not be loaded...
// In any case we now try one more time
catch (InvocationTargetException e) {
if (e.getTargetException() instanceof InterruptedException
|| e.getTargetException() instanceof InterruptedIOException) {
Thread.currentThread().interrupt();
}
} catch (Throwable t) {
}
}
return Class.forName(clazz);
}
}