com.github.datalking.io.SpringFactoriesLoader Maven / Gradle / Ivy
package com.github.datalking.io;
import com.github.datalking.util.ClassUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* @author yaoo on 5/28/18
*/
public abstract class SpringFactoriesLoader {
/**
* The location to look for the factories. Can be present in multiple JAR files.
*/
private static final String FACTORIES_RESOURCE_LOCATION = "META-INF/spring.factories";
private static final Logger logger = LoggerFactory.getLogger(SpringFactoriesLoader.class);
/**
* Load the factory implementations of the given type from the default location,
* using the given class loader.
* The returned factories are ordered in accordance with the OrderComparator.
*
* @param factoryClass the interface or abstract class representing the factory
* @param classLoader the ClassLoader to use for loading (can be {@code null} to use the default)
*/
// public static List loadFactories(Class factoryClass, ClassLoader classLoader) {
// Assert.notNull(factoryClass, "'factoryClass' must not be null");
// ClassLoader classLoaderToUse = classLoader;
// if (classLoaderToUse == null) {
// classLoaderToUse = SpringFactoriesLoader.class.getClassLoader();
// }
// List factoryNames = loadFactoryNames(factoryClass, classLoaderToUse);
// if (logger.isTraceEnabled()) {
// logger.trace("Loaded [" + factoryClass.getName() + "] names: " + factoryNames);
// }
// List result = new ArrayList(factoryNames.size());
// for (String factoryName : factoryNames) {
// result.add(instantiateFactory(factoryName, factoryClass, classLoaderToUse));
// }
// OrderComparator.sort(result);
// return result;
// }
//
// public static List loadFactoryNames(Class factoryClass, ClassLoader classLoader) {
// String factoryClassName = factoryClass.getName();
// try {
// Enumeration urls = (classLoader != null ? classLoader.getResources(FACTORIES_RESOURCE_LOCATION) :
// ClassLoader.getSystemResources(FACTORIES_RESOURCE_LOCATION));
// List result = new ArrayList();
// while (urls.hasMoreElements()) {
// URL url = urls.nextElement();
// Properties properties = PropertiesLoaderUtils.loadProperties(new UrlResource(url));
// String factoryClassNames = properties.getProperty(factoryClassName);
// result.addAll(Arrays.asList(StringUtils.commaDelimitedListToStringArray(factoryClassNames)));
// }
// return result;
// }
// catch (IOException ex) {
// throw new IllegalArgumentException("Unable to load [" + factoryClass.getName() +
// "] factories from location [" + FACTORIES_RESOURCE_LOCATION + "]", ex);
// }
// }
private static T instantiateFactory(String instanceClassName, Class factoryClass, ClassLoader classLoader) {
try {
Class instanceClass = ClassUtils.forName(instanceClassName, classLoader);
if (!factoryClass.isAssignableFrom(instanceClass)) {
throw new IllegalArgumentException("Class [" + instanceClassName + "] is not assignable to [" + factoryClass.getName() + "]");
}
return (T) instanceClass.newInstance();
} catch (Throwable ex) {
throw new IllegalArgumentException("Cannot instantiate factory class: " + factoryClass.getName(), ex);
}
}
}