se.curity.examples.oauth.ExternalResourceLoader.java Source code

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Here is the source code for se.curity.examples.oauth.ExternalResourceLoader.java

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/*
 * Copyright (C) 2016 Curity AB.
 * 
 * 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 se.curity.examples.oauth;

import org.apache.http.client.HttpClient;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.*;
import java.util.Properties;
import java.util.function.Supplier;

final class ExternalResourceLoader {
    private static final Logger _logger = LoggerFactory.getLogger(ExternalResourceLoader.class);

    static final String PROPS_FILE_NAME = "OAuthFilter.properties";
    static final String PROPERTIES_LOCATION = "/META-INF/services/" + PROPS_FILE_NAME;
    static final String HTTP_CLIENT_PROPERTY = "openid.httpClientSupplier.className";

    private static ExternalResourceLoader instance;

    private final Properties _properties;

    public static synchronized ExternalResourceLoader getInstance() {
        if (instance == null) {
            instance = new ExternalResourceLoader();
        }
        return instance;
    }

    private ExternalResourceLoader() {
        _properties = new Properties(defaultProperties());

        InputStream stream = getClass().getResourceAsStream(PROPERTIES_LOCATION);
        if (stream == null) {
            try {
                stream = new BufferedInputStream(new FileInputStream(PROPS_FILE_NAME));
                _logger.info("Found properties file in the working directory");
            } catch (FileNotFoundException e) {
                // not a problem
            }
        }
        if (stream == null) {
            _logger.info("No external config found, using defaults");
        } else {
            try (InputStream input = stream) {
                _properties.load(input);
            } catch (IOException e) {
                _logger.warn("Problem loading properties at " + PROPERTIES_LOCATION, e);
            }
        }
    }

    private static Properties defaultProperties() {
        Properties properties = new Properties();
        properties.put(HTTP_CLIENT_PROPERTY, DefaultJwkHttpClientSupplier.class.getName());
        return properties;
    }

    HttpClient loadJwkHttpClient() {
        String httpClientSupplierClassName = _properties.getProperty(HTTP_CLIENT_PROPERTY);
        try {
            Class<? extends Supplier> supplierType = Class.forName(httpClientSupplierClassName)
                    .asSubclass(Supplier.class);
            _logger.info("Using HttpClientSupplier of type {}", supplierType.getName());
            Supplier<?> supplier = supplierType.newInstance();
            Object httpClient = supplier.get();
            return HttpClient.class.cast(httpClient);
        } catch (Exception e) {
            _logger.warn("Unable to load httpClientSupplier from " + PROPERTIES_LOCATION
                    + "\nWill fallback to the default HTTP Client", e);
            return new DefaultJwkHttpClientSupplier().get();
        }
    }

}