com.michellemay.config.ConfigReader.java Source code

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Here is the source code for com.michellemay.config.ConfigReader.java

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/*
 * Copyright 2015 Michel Lemay
 *
 * 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.michellemay.config;

import java.io.*;
import java.nio.charset.Charset;

import com.fasterxml.jackson.databind.ObjectMapper;

/**
 * Helper class used to read and create Config object.
 *
 * @author Michel Lemay
 */
public class ConfigReader {
    public static final String DEFAULT_CONFIG = "default-profiles.json";
    public static final String TEST_CONFIG = "test-profiles.json";

    /**
     * Read from an InputStream with given encoding.
     *
     * @param inputStream Config input stream.
     * @param encoding Text encoding in the stream.
     *
     * @return New {@link Config} object.
     *
     * @throws IOException if an error occurs while reading the configuration.
     */
    public static Config read(InputStream inputStream, String encoding) throws IOException {
        StringBuilder buffer = new StringBuilder();
        try (BufferedReader reader = new BufferedReader(
                new InputStreamReader(inputStream, Charset.forName(encoding)))) {
            String line;
            while ((line = reader.readLine()) != null) {
                if (buffer.length() > 0) {
                    buffer.append(' ');
                }
                buffer.append(line);
            }
        }

        return read(buffer.toString());
    }

    /**
     * Read from an InputStream in UTF-8.
     *
     * @param inputStream Config input stream.
     *
     * @return New {@link Config} object.
     *
     * @throws IOException if an error occurs while reading the configuration.
     */
    public static Config read(InputStream inputStream) throws IOException {
        return read(inputStream, "utf-8");
    }

    /**
     * Read from a String
     *
     * @param inputConfig Config input string as json.
     *
     * @return New {@link Config} object.
     *
     * @throws IOException if an error occurs while reading the configuration.
     */
    public static Config read(String inputConfig) throws IOException {
        return (new ObjectMapper()).readValue(inputConfig, Config.class);
    }

    /**
     * Load profiles configuration from the classpath in a specific directory.
     *
     * <p>This is usually used to load built-in profiles, shipped with the jar.</p>
     *
     * @param classLoader the ClassLoader to load the profiles from. Use {@code MyClass.class.getClassLoader()}
     * @param configName profile path inside the classpath.
     *
     * @return New {@link Config} object.
     *
     * @throws IOException if an error occurs while reading the configuration.
     */
    public static Config read(ClassLoader classLoader, String configName) throws IOException {
        try (InputStream in = classLoader.getResourceAsStream(configName)) {
            if (in == null) {
                throw new IOException("No config file available named at " + configName + "!");
            }
            return read(in);
        }
    }

    /**
     * Load builtin profiles configuration from the classpath.
     *
     * @return New {@link Config} object.
     *
     * @throws IOException if an error occurs while reading the configuration.
     */
    public static Config readBuiltIn() throws IOException {
        return readBuiltIn(DEFAULT_CONFIG);
    }

    /**
     * Load builtin profiles configuration from the classpath.
     *
     * @param configName profile path inside the classpath.
     *
     * @return New {@link Config} object.
     *
     * @throws IOException if an error occurs while reading the configuration.
     */
    public static Config readBuiltIn(String configName) throws IOException {
        return read(ConfigReader.class.getClassLoader(), configName);
    }
}