WebappLoader.java
/*
* 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.catalina.loader;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
import java.io.File;
import java.io.FilePermission;
import java.io.IOException;
import java.lang.reflect.Constructor;
import java.net.URL;
import java.net.URLClassLoader;
import java.nio.charset.StandardCharsets;
import javax.management.ObjectName;
import javax.servlet.ServletContext;
import org.apache.catalina.Context;
import org.apache.catalina.Globals;
import org.apache.catalina.LifecycleException;
import org.apache.catalina.LifecycleState;
import org.apache.catalina.Loader;
import org.apache.catalina.util.LifecycleMBeanBase;
import org.apache.catalina.util.ToStringUtil;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.ExceptionUtils;
import org.apache.tomcat.util.buf.UDecoder;
import org.apache.tomcat.util.compat.JreCompat;
import org.apache.tomcat.util.modeler.Registry;
import org.apache.tomcat.util.res.StringManager;
/**
* Classloader implementation which is specialized for handling web applications in the most efficient way, while being
* Catalina aware (all accesses to resources are made through {@link org.apache.catalina.WebResourceRoot}). This class
* loader supports detection of modified Java classes, which can be used to implement auto-reload support.
* <p>
* This class loader is configured via the Resources children of its Context prior to calling <code>start()</code>. When
* a new class is required, these Resources will be consulted first to locate the class. If it is not present, the
* system class loader will be used instead.
*
* @author Craig R. McClanahan
* @author Remy Maucherat
*/
public class WebappLoader extends LifecycleMBeanBase implements Loader, PropertyChangeListener {
private static final Log log = LogFactory.getLog(WebappLoader.class);
// ----------------------------------------------------------- Constructors
/**
* Construct a new WebappLoader. The parent class loader will be defined by {@link Context#getParentClassLoader()}.
*/
public WebappLoader() {
this(null);
}
/**
* Construct a new WebappLoader with the specified class loader to be defined as the parent of the ClassLoader we
* ultimately create.
*
* @param parent The parent class loader
*
* @deprecated Use {@link Context#setParentClassLoader(ClassLoader)} to specify the required class loader. This
* method will be removed in Tomcat 10 onwards.
*/
@Deprecated
public WebappLoader(ClassLoader parent) {
super();
this.parentClassLoader = parent;
}
// ----------------------------------------------------- Instance Variables
/**
* The class loader being managed by this Loader component.
*/
private WebappClassLoaderBase classLoader = null;
/**
* The Context with which this Loader has been associated.
*/
private Context context = null;
/**
* The "follow standard delegation model" flag that will be used to configure our ClassLoader.
*/
private boolean delegate = false;
/**
* The Java class name of the ClassLoader implementation to be used. This class should extend WebappClassLoaderBase,
* otherwise, a different loader implementation must be used.
*/
private String loaderClass = ParallelWebappClassLoader.class.getName();
/**
* The parent class loader of the class loader we will create.
*/
private ClassLoader parentClassLoader = null;
/**
* The reloadable flag for this Loader.
*/
private boolean reloadable = false;
/**
* The string manager for this package.
*/
protected static final StringManager sm = StringManager.getManager(WebappLoader.class);
/**
* The property change support for this component.
*/
protected final PropertyChangeSupport support = new PropertyChangeSupport(this);
/**
* Classpath set in the loader.
*/
private String classpath = null;
// ------------------------------------------------------------- Properties
@Override
public ClassLoader getClassLoader() {
return classLoader;
}
@Override
public Context getContext() {
return context;
}
@Override
public void setContext(Context context) {
if (this.context == context) {
return;
}
if (getState().isAvailable()) {
throw new IllegalStateException(sm.getString("webappLoader.setContext.ise"));
}
// Deregister from the old Context (if any)
if (this.context != null) {
this.context.removePropertyChangeListener(this);
}
// Process this property change
Context oldContext = this.context;
this.context = context;
support.firePropertyChange("context", oldContext, this.context);
// Register with the new Container (if any)
if (this.context != null) {
setReloadable(this.context.getReloadable());
this.context.addPropertyChangeListener(this);
}
}
@Override
public boolean getDelegate() {
return this.delegate;
}
@Override
public void setDelegate(boolean delegate) {
boolean oldDelegate = this.delegate;
this.delegate = delegate;
support.firePropertyChange("delegate", Boolean.valueOf(oldDelegate), Boolean.valueOf(this.delegate));
}
/**
* @return the ClassLoader class name.
*/
public String getLoaderClass() {
return this.loaderClass;
}
/**
* Set the ClassLoader class name.
*
* @param loaderClass The new ClassLoader class name
*/
public void setLoaderClass(String loaderClass) {
this.loaderClass = loaderClass;
}
/**
* Set the ClassLoader instance, without relying on reflection This method will also invoke
* {@link #setLoaderClass(String)} with {@code loaderInstance.getClass().getName()} as an argument
*
* @param loaderInstance The new ClassLoader instance to use
*/
public void setLoaderInstance(WebappClassLoaderBase loaderInstance) {
this.classLoader = loaderInstance;
setLoaderClass(loaderInstance.getClass().getName());
}
/**
* Return the reloadable flag for this Loader.
*/
@Override
public boolean getReloadable() {
return this.reloadable;
}
/**
* Set the reloadable flag for this Loader.
*
* @param reloadable The new reloadable flag
*/
@Override
public void setReloadable(boolean reloadable) {
// Process this property change
boolean oldReloadable = this.reloadable;
this.reloadable = reloadable;
support.firePropertyChange("reloadable", Boolean.valueOf(oldReloadable), Boolean.valueOf(this.reloadable));
}
// --------------------------------------------------------- Public Methods
@Override
public void addPropertyChangeListener(PropertyChangeListener listener) {
support.addPropertyChangeListener(listener);
}
@Override
public void backgroundProcess() {
if (reloadable && modified()) {
Thread currentThread = Thread.currentThread();
try {
currentThread.setContextClassLoader(WebappLoader.class.getClassLoader());
if (context != null) {
context.reload();
}
} finally {
if (context != null && context.getLoader() != null) {
currentThread.setContextClassLoader(context.getLoader().getClassLoader());
}
}
}
}
public String[] getLoaderRepositories() {
if (classLoader == null) {
return new String[0];
}
URL[] urls = classLoader.getURLs();
String[] result = new String[urls.length];
for (int i = 0; i < urls.length; i++) {
result[i] = urls[i].toExternalForm();
}
return result;
}
public String getLoaderRepositoriesString() {
String repositories[] = getLoaderRepositories();
StringBuilder sb = new StringBuilder();
for (String repository : repositories) {
sb.append(repository).append(':');
}
return sb.toString();
}
/**
* Classpath, as set in org.apache.catalina.jsp_classpath context property
*
* @return The classpath
*/
public String getClasspath() {
return classpath;
}
@Override
public boolean modified() {
return classLoader != null ? classLoader.modified() : false;
}
@Override
public void removePropertyChangeListener(PropertyChangeListener listener) {
support.removePropertyChangeListener(listener);
}
@Override
public String toString() {
return ToStringUtil.toString(this, context);
}
/**
* Start associated {@link ClassLoader} and implement the requirements of
* {@link org.apache.catalina.util.LifecycleBase#startInternal()}.
*
* @exception LifecycleException if this component detects a fatal error that prevents this component from being
* used
*/
@Override
protected void startInternal() throws LifecycleException {
if (log.isDebugEnabled()) {
log.debug(sm.getString("webappLoader.starting"));
}
if (context.getResources() == null) {
log.info(sm.getString("webappLoader.noResources", context));
setState(LifecycleState.STARTING);
return;
}
// Construct a class loader based on our current repositories list
try {
classLoader = createClassLoader();
classLoader.setResources(context.getResources());
classLoader.setDelegate(this.delegate);
// Configure our repositories
setClassPath();
setPermissions();
classLoader.start();
String contextName = context.getName();
if (!contextName.startsWith("/")) {
contextName = "/" + contextName;
}
ObjectName cloname =
new ObjectName(context.getDomain() + ":type=" + classLoader.getClass().getSimpleName() + ",host=" +
context.getParent().getName() + ",context=" + contextName);
Registry.getRegistry(null, null).registerComponent(classLoader, cloname, null);
} catch (Throwable t) {
t = ExceptionUtils.unwrapInvocationTargetException(t);
ExceptionUtils.handleThrowable(t);
throw new LifecycleException(sm.getString("webappLoader.startError"), t);
}
setState(LifecycleState.STARTING);
}
/**
* Stop associated {@link ClassLoader} and implement the requirements of
* {@link org.apache.catalina.util.LifecycleBase#stopInternal()}.
*
* @exception LifecycleException if this component detects a fatal error that prevents this component from being
* used
*/
@Override
protected void stopInternal() throws LifecycleException {
if (log.isDebugEnabled()) {
log.debug(sm.getString("webappLoader.stopping"));
}
setState(LifecycleState.STOPPING);
// Remove context attributes as appropriate
ServletContext servletContext = context.getServletContext();
servletContext.removeAttribute(Globals.CLASS_PATH_ATTR);
// Throw away our current class loader if any
if (classLoader != null) {
try {
classLoader.stop();
} finally {
classLoader.destroy();
}
// classLoader must be non-null to have been registered
try {
String contextName = context.getName();
if (!contextName.startsWith("/")) {
contextName = "/" + contextName;
}
ObjectName cloname =
new ObjectName(context.getDomain() + ":type=" + classLoader.getClass().getSimpleName() +
",host=" + context.getParent().getName() + ",context=" + contextName);
Registry.getRegistry(null, null).unregisterComponent(cloname);
} catch (Exception e) {
log.warn(sm.getString("webappLoader.stopError"), e);
}
}
classLoader = null;
}
// ----------------------------------------- PropertyChangeListener Methods
/**
* Process property change events from our associated Context.
*
* @param event The property change event that has occurred
*/
@Override
public void propertyChange(PropertyChangeEvent event) {
// Validate the source of this event
if (!(event.getSource() instanceof Context)) {
return;
}
// Process a relevant property change
if (event.getPropertyName().equals("reloadable")) {
try {
setReloadable(((Boolean) event.getNewValue()).booleanValue());
} catch (NumberFormatException e) {
log.error(sm.getString("webappLoader.reloadable", event.getNewValue().toString()));
}
}
}
// ------------------------------------------------------- Private Methods
/**
* Create associated classLoader.
*/
private WebappClassLoaderBase createClassLoader() throws Exception {
if (classLoader != null) {
return classLoader;
}
if (parentClassLoader == null) {
parentClassLoader = context.getParentClassLoader();
} else {
context.setParentClassLoader(parentClassLoader);
}
if (ParallelWebappClassLoader.class.getName().equals(loaderClass)) {
return new ParallelWebappClassLoader(parentClassLoader);
}
Class<?> clazz = Class.forName(loaderClass);
WebappClassLoaderBase classLoader = null;
Class<?>[] argTypes = { ClassLoader.class };
Object[] args = { parentClassLoader };
Constructor<?> constr = clazz.getConstructor(argTypes);
classLoader = (WebappClassLoaderBase) constr.newInstance(args);
return classLoader;
}
/**
* Configure associated class loader permissions.
*/
private void setPermissions() {
if (!Globals.IS_SECURITY_ENABLED) {
return;
}
if (context == null) {
return;
}
// Tell the class loader the root of the context
ServletContext servletContext = context.getServletContext();
// Assigning permissions for the work directory
File workDir = (File) servletContext.getAttribute(ServletContext.TEMPDIR);
if (workDir != null) {
try {
String workDirPath = workDir.getCanonicalPath();
classLoader.addPermission(new FilePermission(workDirPath, "read,write"));
classLoader.addPermission(new FilePermission(workDirPath + File.separator + "-", "read,write,delete"));
} catch (IOException e) {
// Ignore
}
}
for (URL url : context.getResources().getBaseUrls()) {
classLoader.addPermission(url);
}
}
/**
* Set the appropriate context attribute for our class path. This is required only because Jasper depends on it.
*/
private void setClassPath() {
// Validate our current state information
if (context == null) {
return;
}
ServletContext servletContext = context.getServletContext();
if (servletContext == null) {
return;
}
StringBuilder classpath = new StringBuilder();
// Assemble the class path information from our class loader chain
ClassLoader loader = getClassLoader();
if (delegate && loader != null) {
// Skip the webapp loader for now as delegation is enabled
loader = loader.getParent();
}
while (loader != null) {
if (!buildClassPath(classpath, loader)) {
break;
}
loader = loader.getParent();
}
if (delegate) {
// Delegation was enabled, go back and add the webapp paths
loader = getClassLoader();
if (loader != null) {
buildClassPath(classpath, loader);
}
}
this.classpath = classpath.toString();
// Store the assembled class path as a servlet context attribute
servletContext.setAttribute(Globals.CLASS_PATH_ATTR, this.classpath);
}
private boolean buildClassPath(StringBuilder classpath, ClassLoader loader) {
if (loader instanceof URLClassLoader) {
URL repositories[] = ((URLClassLoader) loader).getURLs();
for (URL url : repositories) {
String repository = url.toString();
if (repository.startsWith("file://")) {
repository = UDecoder.URLDecode(repository.substring(7), StandardCharsets.UTF_8);
} else if (repository.startsWith("file:")) {
repository = UDecoder.URLDecode(repository.substring(5), StandardCharsets.UTF_8);
} else {
continue;
}
if (repository == null) {
continue;
}
if (classpath.length() > 0) {
classpath.append(File.pathSeparator);
}
classpath.append(repository);
}
} else if (loader == ClassLoader.getSystemClassLoader()) {
// Java 9 onwards. The internal class loaders no longer extend
// URLCLassLoader
String cp = System.getProperty("java.class.path");
if (cp != null && cp.length() > 0) {
if (classpath.length() > 0) {
classpath.append(File.pathSeparator);
}
classpath.append(cp);
}
return false;
} else {
// Ignore Graal "unknown" classloader
if (!JreCompat.isGraalAvailable()) {
log.info(sm.getString("webappLoader.unknownClassLoader", loader, loader.getClass()));
}
return false;
}
return true;
}
@Override
protected String getDomainInternal() {
return context.getDomain();
}
@Override
protected String getObjectNameKeyProperties() {
StringBuilder name = new StringBuilder("type=Loader");
name.append(",host=");
name.append(context.getParent().getName());
name.append(",context=");
String contextName = context.getName();
if (!contextName.startsWith("/")) {
name.append('/');
}
name.append(contextName);
return name.toString();
}
}