javax.xml.bind.ContextFinder Maven / Gradle / Ivy
/*
* Copyright 2008 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/
package javax.xml.bind;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.net.URL;
import java.util.Map;
import java.util.Properties;
import java.util.StringTokenizer;
import java.util.logging.ConsoleHandler;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.security.AccessController;
import java.security.PrivilegedAction;
import static javax.xml.bind.JAXBContext.JAXB_CONTEXT_FACTORY;
//import java.lang.reflect.InvocationTargetException;
/**
* This class is package private and therefore is not exposed as part of the
* JAXB API.
*
* This code is designed to implement the JAXB 1.0 spec pluggability feature
*
* @author - Ryan Shoemaker, Sun Microsystems, Inc.
* @see JAXBContext
*/
class ContextFinder {
private static final Logger logger;
static {
logger = Logger.getLogger("javax.xml.bind");
try {
if (AccessController.doPrivileged(new GetPropertyAction("jaxb.debug")) != null) {
// disconnect the logger from a bigger framework (if any)
// and take the matters into our own hands
logger.setUseParentHandlers(false);
logger.setLevel(Level.ALL);
ConsoleHandler handler = new ConsoleHandler();
handler.setLevel(Level.ALL);
logger.addHandler(handler);
} else {
// don't change the setting of this logger
// to honor what other frameworks
// have done on configurations.
}
} catch(Throwable t) {
// just to be extra safe. in particular System.getProperty may throw
// SecurityException.
}
}
/**
* If the {@link InvocationTargetException} wraps an exception that shouldn't be wrapped,
* throw the wrapped exception.
*/
private static void handleInvocationTargetException(InvocationTargetException x) throws JAXBException {
Throwable t = x.getTargetException();
if( t != null ) {
if( t instanceof JAXBException )
// one of our exceptions, just re-throw
throw (JAXBException)t;
if( t instanceof RuntimeException )
// avoid wrapping exceptions unnecessarily
throw (RuntimeException)t;
if( t instanceof Error )
throw (Error)t;
}
}
/**
* Determine if two types (JAXBContext in this case) will generate a ClassCastException.
*
* For example, (targetType)originalType
*
* @param originalType
* The Class object of the type being cast
* @param targetType
* The Class object of the type that is being cast to
* @return JAXBException to be thrown.
*/
private static JAXBException handleClassCastException(Class originalType, Class targetType) {
final URL targetTypeURL = which(targetType);
return new JAXBException(Messages.format(Messages.ILLEGAL_CAST,
// we don't care where the impl class is, we want to know where JAXBContext lives in the impl
// class' ClassLoader
originalType.getClassLoader().getResource("javax/xml/bind/JAXBContext.class"),
targetTypeURL));
}
/**
* Create an instance of a class using the specified ClassLoader
*/
static JAXBContext newInstance( String contextPath,
String className,
ClassLoader classLoader,
Map properties )
throws JAXBException
{
try {
Class spiClass = safeLoadClass(className,classLoader);
/*
* javax.xml.bind.context.factory points to a class which has a
* static method called 'createContext' that
* returns a javax.xml.JAXBContext.
*/
Object context = null;
// first check the method that takes Map as the third parameter.
// this is added in 2.0.
try {
Method m = spiClass.getMethod("createContext",String.class,ClassLoader.class,Map.class);
// any failure in invoking this method would be considered fatal
context = m.invoke(null,contextPath,classLoader,properties);
} catch (NoSuchMethodException e) {
// it's not an error for the provider not to have this method.
}
if(context==null) {
// try the old method that doesn't take properties. compatible with 1.0.
// it is an error for an implementation not to have both forms of the createContext method.
Method m = spiClass.getMethod("createContext",String.class,ClassLoader.class);
// any failure in invoking this method would be considered fatal
context = m.invoke(null,contextPath,classLoader);
}
if(!(context instanceof JAXBContext)) {
// the cast would fail, so generate an exception with a nice message
throw handleClassCastException(context.getClass(), JAXBContext.class);
}
return (JAXBContext)context;
} catch (ClassNotFoundException x) {
throw new JAXBException(
Messages.format( Messages.PROVIDER_NOT_FOUND, className ),
x);
} catch (InvocationTargetException x) {
handleInvocationTargetException(x);
// for other exceptions, wrap the internal target exception
// with a JAXBException
Throwable e = x;
if(x.getTargetException()!=null)
e = x.getTargetException();
throw new JAXBException( Messages.format( Messages.COULD_NOT_INSTANTIATE, className, e ), e );
} catch (RuntimeException x) {
// avoid wrapping RuntimeException to JAXBException,
// because it indicates a bug in this code.
throw x;
} catch (Exception x) {
// can't catch JAXBException because the method is hidden behind
// reflection. Root element collisions detected in the call to
// createContext() are reported as JAXBExceptions - just re-throw it
// some other type of exception - just wrap it
throw new JAXBException(
Messages.format( Messages.COULD_NOT_INSTANTIATE, className, x ),
x);
}
}
/**
* Create an instance of a class using the specified ClassLoader
*/
static JAXBContext newInstance(
Class[] classes,
Map properties,
String className) throws JAXBException {
ClassLoader cl = Thread.currentThread().getContextClassLoader();
Class spi;
try {
spi = safeLoadClass(className,cl);
} catch (ClassNotFoundException e) {
throw new JAXBException(e);
}
if(logger.isLoggable(Level.FINE)) {
// extra check to avoid costly which operation if not logged
logger.fine("loaded "+className+" from "+which(spi));
}
Method m;
try {
m = spi.getMethod("createContext", Class[].class, Map.class);
} catch (NoSuchMethodException e) {
throw new JAXBException(e);
}
try {
Object context = m.invoke(null, classes, properties);
if(!(context instanceof JAXBContext)) {
// the cast would fail, so generate an exception with a nice message
throw handleClassCastException(context.getClass(), JAXBContext.class);
}
return (JAXBContext)context;
} catch (IllegalAccessException e) {
throw new JAXBException(e);
} catch (InvocationTargetException e) {
handleInvocationTargetException(e);
Throwable x = e;
if (e.getTargetException() != null)
x = e.getTargetException();
throw new JAXBException(x);
}
}
static JAXBContext find(String factoryId, String contextPath, ClassLoader classLoader, Map properties ) throws JAXBException {
// TODO: do we want/need another layer of searching in $java.home/lib/jaxb.properties like JAXP?
final String jaxbContextFQCN = JAXBContext.class.getName();
// search context path for jaxb.properties first
StringBuilder propFileName;
StringTokenizer packages = new StringTokenizer( contextPath, ":" );
String factoryClassName;
if(!packages.hasMoreTokens())
// no context is specified
throw new JAXBException(Messages.format(Messages.NO_PACKAGE_IN_CONTEXTPATH));
logger.fine("Searching jaxb.properties");
while( packages.hasMoreTokens() ) {
String packageName = packages.nextToken(":").replace('.','/');
// com.acme.foo - > com/acme/foo/jaxb.properties
propFileName = new StringBuilder().append(packageName).append("/jaxb.properties");
Properties props = loadJAXBProperties( classLoader, propFileName.toString() );
if (props != null) {
if (props.containsKey(factoryId)) {
factoryClassName = props.getProperty(factoryId);
return newInstance( contextPath, factoryClassName, classLoader, properties );
} else {
throw new JAXBException(Messages.format(Messages.MISSING_PROPERTY, packageName, factoryId));
}
}
}
logger.fine("Searching the system property");
// search for a system property second (javax.xml.bind.JAXBContext)
factoryClassName = AccessController.doPrivileged(new GetPropertyAction(jaxbContextFQCN));
if( factoryClassName != null ) {
return newInstance( contextPath, factoryClassName, classLoader, properties );
}
logger.fine("Searching META-INF/services");
// search META-INF services next
BufferedReader r;
try {
final StringBuilder resource = new StringBuilder().append("META-INF/services/").append(jaxbContextFQCN);
final InputStream resourceStream =
classLoader.getResourceAsStream(resource.toString());
if (resourceStream != null) {
r = new BufferedReader(new InputStreamReader(resourceStream, "UTF-8"));
factoryClassName = r.readLine().trim();
r.close();
return newInstance(contextPath, factoryClassName, classLoader, properties);
} else {
logger.fine("Unable to load:" + resource.toString());
}
} catch (UnsupportedEncodingException e) {
// should never happen
throw new JAXBException(e);
} catch (IOException e) {
throw new JAXBException(e);
}
// else no provider found
logger.fine("Trying to create the platform default provider");
return newInstance(contextPath, PLATFORM_DEFAULT_FACTORY_CLASS, classLoader, properties);
}
// TODO: log each step in the look up process
static JAXBContext find( Class[] classes, Map properties ) throws JAXBException {
// TODO: do we want/need another layer of searching in $java.home/lib/jaxb.properties like JAXP?
final String jaxbContextFQCN = JAXBContext.class.getName();
String factoryClassName;
// search for jaxb.properties in the class loader of each class first
for (final Class c : classes) {
// this classloader is used only to load jaxb.properties, so doing this should be safe.
ClassLoader classLoader = AccessController.doPrivileged(new PrivilegedAction() {
public ClassLoader run() {
return c.getClassLoader();
}
});
Package pkg = c.getPackage();
if(pkg==null)
continue; // this is possible for primitives, arrays, and classes that are loaded by poorly implemented ClassLoaders
String packageName = pkg.getName().replace('.', '/');
// TODO: do we want to optimize away searching the same package? org.Foo, org.Bar, com.Baz
// classes from the same package might come from different class loades, so it might be a bad idea
// TODO: it's easier to look things up from the class
// c.getResourceAsStream("jaxb.properties");
// build the resource name and use the property loader code
String resourceName = packageName+"/jaxb.properties";
logger.fine("Trying to locate "+resourceName);
Properties props = loadJAXBProperties(classLoader, resourceName);
if (props == null) {
logger.fine(" not found");
} else {
logger.fine(" found");
if (props.containsKey(JAXB_CONTEXT_FACTORY)) {
// trim() seems redundant, but adding to satisfy customer complaint
factoryClassName = props.getProperty(JAXB_CONTEXT_FACTORY).trim();
return newInstance(classes, properties, factoryClassName);
} else {
throw new JAXBException(Messages.format(Messages.MISSING_PROPERTY, packageName, JAXB_CONTEXT_FACTORY));
}
}
}
// search for a system property second (javax.xml.bind.JAXBContext)
logger.fine("Checking system property "+jaxbContextFQCN);
factoryClassName = AccessController.doPrivileged(new GetPropertyAction(jaxbContextFQCN));
if( factoryClassName != null ) {
logger.fine(" found "+factoryClassName);
return newInstance( classes, properties, factoryClassName );
}
logger.fine(" not found");
// search META-INF services next
logger.fine("Checking META-INF/services");
BufferedReader r;
try {
final String resource = new StringBuilder("META-INF/services/").append(jaxbContextFQCN).toString();
ClassLoader classLoader = Thread.currentThread().getContextClassLoader();
URL resourceURL;
if(classLoader==null)
resourceURL = ClassLoader.getSystemResource(resource);
else
resourceURL = classLoader.getResource(resource);
if (resourceURL != null) {
logger.fine("Reading "+resourceURL);
r = new BufferedReader(new InputStreamReader(resourceURL.openStream(), "UTF-8"));
factoryClassName = r.readLine().trim();
return newInstance(classes, properties, factoryClassName);
} else {
logger.fine("Unable to find: " + resource);
}
} catch (UnsupportedEncodingException e) {
// should never happen
throw new JAXBException(e);
} catch (IOException e) {
throw new JAXBException(e);
}
// else no provider found
logger.fine("Trying to create the platform default provider");
return newInstance(classes, properties, PLATFORM_DEFAULT_FACTORY_CLASS);
}
private static Properties loadJAXBProperties( ClassLoader classLoader,
String propFileName )
throws JAXBException {
Properties props = null;
try {
URL url;
if(classLoader==null)
url = ClassLoader.getSystemResource(propFileName);
else
url = classLoader.getResource( propFileName );
if( url != null ) {
logger.fine("loading props from "+url);
props = new Properties();
InputStream is = url.openStream();
props.load( is );
is.close();
}
} catch( IOException ioe ) {
logger.log(Level.FINE,"Unable to load "+propFileName,ioe);
throw new JAXBException( ioe.toString(), ioe );
}
return props;
}
/**
* Search the given ClassLoader for an instance of the specified class and
* return a string representation of the URL that points to the resource.
*
* @param clazz
* The class to search for
* @param loader
* The ClassLoader to search. If this parameter is null, then the
* system class loader will be searched
* @return
* the URL for the class or null if it wasn't found
*/
static URL which(Class clazz, ClassLoader loader) {
String classnameAsResource = clazz.getName().replace('.', '/') + ".class";
if(loader == null) {
loader = ClassLoader.getSystemClassLoader();
}
return loader.getResource(classnameAsResource);
}
/**
* Get the URL for the Class from it's ClassLoader.
*
* Convenience method for {@link #which(Class, ClassLoader)}.
*
* Equivalent to calling: which(clazz, clazz.getClassLoader())
*
* @param clazz
* The class to search for
* @return
* the URL for the class or null if it wasn't found
*/
static URL which(Class clazz) {
return which(clazz, clazz.getClassLoader());
}
/**
* When JAXB is in J2SE, rt.jar has to have a JAXB implementation.
* However, rt.jar cannot have META-INF/services/javax.xml.bind.JAXBContext
* because if it has, it will take precedence over any file that applications have
* in their jar files.
*
*
* When the user bundles his own JAXB implementation, we'd like to use it, and we
* want the platform default to be used only when there's no other JAXB provider.
*
*
* For this reason, we have to hard-code the class name into the API.
*/
private static final String PLATFORM_DEFAULT_FACTORY_CLASS = "com.sun.xml.internal.bind.v2.ContextFactory";
/**
* Loads the class, provided that the calling thread has an access to the class being loaded.
*/
private static Class safeLoadClass(String className, ClassLoader classLoader) throws ClassNotFoundException {
logger.fine("Trying to load "+className);
try {
// make sure that the current thread has an access to the package of the given name.
SecurityManager s = System.getSecurityManager();
if (s != null) {
int i = className.lastIndexOf('.');
if (i != -1) {
s.checkPackageAccess(className.substring(0,i));
}
}
if (classLoader == null) {
return Class.forName(className);
} else {
return classLoader.loadClass(className);
}
} catch (SecurityException se) {
// anyone can access the platform default factory class without permission
if (PLATFORM_DEFAULT_FACTORY_CLASS.equals(className)) {
return Class.forName(className);
}
throw se;
}
}
}
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