ResolverFactory.java
/*
* Copyright (c) 2018, WSO2 Inc. (http://www.wso2.org) All Rights Reserved.
*
* Licensed 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.synapse.config.xml.endpoints.resolvers;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.synapse.config.xml.MediatorFactoryFinder;
import java.util.ServiceLoader;
import java.util.HashMap;
import java.util.Map;
import java.util.Objects;
import java.util.regex.Matcher;
import java.util.regex.Pattern;
/**
* Resolver Factory which can be used to register resolvers and retrieve a resolver for a given type.
*/
public class ResolverFactory {
private final int RESOLVER_INDEX = 2;
private static ResolverFactory resolverFactory = new ResolverFactory();
private final Pattern startPattern = Pattern.compile("(^[a-zA-Z0-9])|(^$)|(^\\{)");
private final Pattern rePattern = Pattern.compile("(\\$)([a-zA-Z0-9]+):([_a-zA-Z0-9]+)");
private static final Log log = LogFactory.getLog(MediatorFactoryFinder.class);
private Map<String, Class<? extends Resolver>> resolverMap = new HashMap<>();
/**
* This function return an object of Resolver factory
* @return resolverFactory
*/
public static ResolverFactory getInstance() {
return resolverFactory;
}
private ResolverFactory() {
registerResolvers();
registerExterns();
}
/**
* This function returns a resolver based on the variable passed
* @param input variable which is used decode and retrieve the resolver
* @return resolver object
*/
public Resolver getResolver(String input) {
Matcher matcher = startPattern.matcher(input);
if (matcher.find()) {
Resolver resolver = new DefaultResolver();
resolver.setVariable(input);
return resolver;
}
matcher = rePattern.matcher(input);
Resolver resolverObject = null;
if (matcher.find()) {
Class<? extends Resolver> resolverClass = resolverMap.get(matcher.group(RESOLVER_INDEX).toLowerCase());
if (resolverClass != null) {
try {
resolverObject = resolverClass.newInstance();
resolverObject.setVariable(matcher.group(3));
} catch (IllegalAccessException | InstantiationException e) {
throw new ResolverException("Resolver could not be found");
}
}
}
if (resolverObject != null) {
return resolverObject;
}
else {
throw new ResolverException("Resolver could not be found");
}
}
private void registerResolvers() {
resolverMap.put("system", SystemResolver.class);
}
private void registerExterns() {
ServiceLoader<Resolver> loaders = ServiceLoader.load(Resolver.class);
for (Resolver resolver : loaders) {
String className = resolver.getClass().getName();
String[] packageList = className.split(".");
className = packageList[packageList.length - 1];
if (resolverMap.get(className.toLowerCase()) == null) {
resolverMap.put(className.toLowerCase(), resolver.getClass());
if (log.isDebugEnabled()) {
log.debug("Added Resolver " + className + " to resolver factory ");
}
}
else {
if (log.isDebugEnabled()) {
log.debug("Failed to Resolver " + className + " to resolver factory. Already exist");
}
}
}
}
}