/**
* 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.camel.impl.converter;
import org.apache.camel.Converter;
import org.apache.camel.TypeConverter;
import org.apache.camel.impl.CachingInjector;
import org.apache.camel.util.ObjectHelper;
import org.apache.camel.util.ResolverUtil;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.lang.reflect.Method;
import static java.lang.reflect.Modifier.*;
import java.net.URL;
import java.util.Enumeration;
import java.util.HashSet;
import java.util.Set;
import java.util.StringTokenizer;
/**
* A class which will auto-discover converter objects and methods to pre-load
* the registry of converters on startup
*
* @version $Revision: 573793 $
*/
public class AnnotationTypeConverterLoader implements TypeConverterLoader {
public static final String META_INF_SERVICES = "META-INF/services/org/apache/camel/TypeConverter";
private static final transient Log LOG = LogFactory.getLog(AnnotationTypeConverterLoader.class);
private ResolverUtil resolver = new ResolverUtil();
private Set<Class> visitedClasses = new HashSet<Class>();
public void load(TypeConverterRegistry registry) throws Exception {
String[] packageNames = findPackageNames();
resolver.findAnnotated(Converter.class, packageNames);
Set<Class> classes = resolver.getClasses();
for (Class type : classes) {
if (LOG.isDebugEnabled()) {
LOG.debug("Loading converter class: " + ObjectHelper.name(type));
}
loadConverterMethods(registry, type);
}
}
/**
* Finds the names of the packages to search for on the classpath looking
* for text files on the classpath at the
*
* @return a collection of packages to search for
* @throws IOException
* @{link #META_INF_SERVICES} location
*/
protected String[] findPackageNames() throws IOException {
Set<String> packages = new HashSet<String>();
findPackages(packages, Thread.currentThread().getContextClassLoader());
findPackages(packages, getClass().getClassLoader());
return packages.toArray(new String[packages.size()]);
}
protected void findPackages(Set<String> packages, ClassLoader classLoader) throws IOException {
Enumeration<URL> resources = classLoader.getResources(META_INF_SERVICES);
while (resources.hasMoreElements()) {
URL url = resources.nextElement();
if (url != null) {
BufferedReader reader = new BufferedReader(new InputStreamReader(url.openStream()));
try {
while (true) {
String line = reader.readLine();
if (line == null) {
break;
}
line = line.trim();
if (line.startsWith("#") || line.length() == 0) {
continue;
}
tokenize(packages, line);
}
}
finally {
try {
reader.close();
}
catch (IOException e) {
LOG.warn("Caught exception closing stream: " + e, e);
}
}
}
}
}
/**
* Tokenizes the line from the META-IN/services file using commas and
* ignoring whitespace between packages
*/
protected void tokenize(Set<String> packages, String line) {
StringTokenizer iter = new StringTokenizer(line, ",");
while (iter.hasMoreTokens()) {
String name = iter.nextToken().trim();
if (name.length() > 0) {
packages.add(name);
}
}
}
/**
* Loads all of the converter methods for the given type
*/
protected void loadConverterMethods(TypeConverterRegistry registry, Class type) {
if (visitedClasses.contains(type)) {
return;
}
visitedClasses.add(type);
try {
Method[] methods = type.getDeclaredMethods();
CachingInjector injector = null;
for (Method method : methods) {
Converter annotation = method.getAnnotation(Converter.class);
if (annotation != null) {
Class<?>[] parameterTypes = method.getParameterTypes();
if (parameterTypes == null || parameterTypes.length != 1) {
LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " + method
+ " as a converter method should have one parameter");
}
else {
int modifiers = method.getModifiers();
if (isAbstract(modifiers) || !isPublic(modifiers)) {
LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: " + method
+ " as a converter method is not a public and concrete method");
}
else {
Class toType = method.getReturnType();
if (toType.equals(Void.class)) {
LOG.warn("Ignoring bad converter on type: " + type.getName() + " method: "
+ method + " as a converter method returns a void method");
}
else {
Class fromType = parameterTypes[0];
if (isStatic(modifiers)) {
registerTypeConverter(registry, method, toType, fromType,
new StaticMethodTypeConverter(method));
}
else {
if (injector == null) {
injector = new CachingInjector(registry, type);
}
registerTypeConverter(registry, method, toType, fromType,
new InstanceMethodTypeConverter(injector, method));
}
}
}
}
}
}
Class superclass = type.getSuperclass();
if (superclass != null && !superclass.equals(Object.class)) {
loadConverterMethods(registry, superclass);
}
}
catch (NoClassDefFoundError e) {
LOG.debug("Ignoring converter type: " + type.getName() + " as a dependent class could not be found: " + e, e);
}
}
protected void registerTypeConverter(TypeConverterRegistry registry, Method method,
Class toType, Class fromType, TypeConverter typeConverter) {
registry.addTypeConverter(toType, fromType, typeConverter);
}
}