com.covisint.platform.oauth.client.token.sdk.AbstractClasspathPropertyLoader Maven / Gradle / Ivy
/*
* Copyright 2015 Covisint
*
* 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 com.covisint.platform.oauth.client.token.sdk;
import java.io.IOException;
import java.io.InputStream;
import java.util.Properties;
/** Abstract property loader. */
abstract class AbstractClasspathPropertyLoader {
/** The loaded properties. */
private final Properties properties;
/** Initializing constructor. */
public AbstractClasspathPropertyLoader() {
final String filename = getPropertyFileName();
InputStream input = getResource(filename);
if (input == null) {
// Retry previous attempts, but this time, from the root of the classpath.
input = getResource("/" + filename);
}
if (input == null) {
throw new IllegalStateException("Could not locate resource in classpath: " + filename);
}
properties = new Properties();
try {
properties.load(input);
} catch (final IOException e) {
throw new IllegalStateException(e);
}
}
/**
* Attempt to read an inputstream into the given resource.
*
* @param resource The resource to locate.
* @return Returns an inputstream into the given resource, or null if the resource couldn't be located.
*/
private InputStream getResource(String resource) {
// First try and load it from the current thread's classloaded.
InputStream input = Thread.currentThread().getContextClassLoader().getResourceAsStream(resource);
if (input == null) {
// Next, attempt to get it from the classloader of this static class.
input = AbstractClasspathPropertyLoader.class.getResourceAsStream(resource);
}
if (input == null) {
// Finally, try the classloader of the runtime instance of this class.
input = getClass().getResourceAsStream(resource);
}
return input;
}
/**
* Returns the name of the property file to load. Must exist in the classpath.
*
* @return Returns the name of the property file to load.
*/
protected abstract String getPropertyFileName();
/**
* Gets the properties loaded by this loader.
*
* @return Returns the loaded properties.
*/
protected final Properties getProperties() {
return properties;
}
}