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/*
* Copyright (c) 2013 Univocity Software Pty Ltd. All rights reserved.
* This file is subject to the terms and conditions defined in file
* 'LICENSE.txt', which is part of this source code package.
*/
package com.univocity.api;
import java.util.*;
import java.util.concurrent.*;
/**
* This is the entry point to univocity's internal implementation classes. It connects the resources in the public API to their actual implementations in univocity's jars.
*
* In some circumstances, you might need to configure the class loader before being able to obtain instances of {@link CommonFactoryProvider} from univocity.jar.
* If that is the case, use the {@link #setClassLoader(ClassLoader)} method before calling the {@link #build(Class, Object...)}} method.
*
* @author Univocity Software Pty Ltd - [email protected]
*/
public final class Builder {
private static ConcurrentHashMap providers = new ConcurrentHashMap();
private static ServiceLoader factoryProviderLoader = ServiceLoader.load(CommonFactoryProvider.class);
/**
* Defines the class loader to be used to load univocity implementation classes (from univocity.jar)
*
* @param classLoader The class loader to be used to load provider classes, or null if the system class loader is to be used.
*/
public static final synchronized void setClassLoader(ClassLoader classLoader) {
factoryProviderLoader = ServiceLoader.load(CommonFactoryProvider.class, classLoader);
providers.clear();
}
/**
* Creates a new instance of the given type, using the given arguments
*
* @param builderType the type whose instance must be created
* @param args the arguments to be used by the concrete implementation of the given type.
* @param the type of the object that will be returned by this method.
*
* @return an instance of the given type.
*/
public static final T build(Class builderType, Object... args) {
T out = null;
CommonFactoryProvider builder = providers.get(builderType);
if (builder == null && !providers.containsKey(builderType)) {
if (!providers.isEmpty()) {
for (Map.Entry e : providers.entrySet()) {
try {
out = e.getValue().build(builderType, args);
providers.put(builderType, e.getValue());
return out;
} catch (Throwable t) {
//ignore
}
}
}
for (CommonFactoryProvider provider : factoryProviderLoader) {
try {
out = provider.build(builderType, args);
providers.put(builderType, provider);
return out;
} catch (Throwable t) {
//ignore
}
}
if(builderType != null) {
providers.put(builderType, new CommonFactoryProvider() {
@Override
public T build(Class builderType, Object... args) {
return null;
}
});
}
} else if (builder != null){
out = builder.build(builderType, args);
}
if (out == null) {
throw new IllegalStateException("Unable to load implementation of " + builderType.getName() + ".");
}
return out;
}
}