EncodingUtils.java

/* 
 * 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 org.ngrinder.common.util;

import com.ibm.icu.text.CharsetDetector;
import com.ibm.icu.text.CharsetMatch;
import org.apache.commons.lang.StringUtils;

import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.nio.charset.Charset;

import static org.ngrinder.common.util.ExceptionUtils.processException;

/**
 * Automatic encoding detection utility.
 * 
 * @author JunHo Yoon
 * @since 3.0
 */
public abstract class EncodingUtils {

	private static final int MINIMAL_CONFIDENCE_LEVEL = 70;

	/**
	 * Decode the byte array with auto encoding detection feature.
	 * 
	 * @param data
	 *            byte array
	 * @param defaultEncoding
	 *            the default encoding if no encoding is sure.
	 * @return decoded string
	 * @throws IOException
	 *             occurs when the decoding is failed.
	 */
	public static String getAutoDecodedString(byte[] data, String defaultEncoding) throws IOException {
		return new String(data, detectEncoding(data, defaultEncoding));
	}

	/**
	 * Detect encoding of given data.
	 * 
	 * @param data
	 *            byte array
	 * @param defaultEncoding
	 *            the default encoding if no encoding is sure.
	 * @return encoding name detected encoding name
	 * @throws IOException
	 *             occurs when the detection is failed.
	 */
	public static String detectEncoding(byte[] data, String defaultEncoding) throws IOException {
		CharsetDetector detector = new CharsetDetector();
		detector.setText(data);
		CharsetMatch cm = detector.detect();
		String estimatedEncoding = cm.getName();
		boolean isReliable = Charset.isSupported(estimatedEncoding) && cm.getConfidence() >= MINIMAL_CONFIDENCE_LEVEL;
		return isReliable ? estimatedEncoding : defaultEncoding;
	}

	/**
	 * Encode the given path with UTF-8.
	 *
	 * "/" is not encoded.
	 * @param path path
	 * @return encoded path
	 */
	public static String encodePathWithUTF8(String path) {
		try {
			StringBuilder result = new StringBuilder();
			for (char each : path.toCharArray()) {
				if (each == '/') {
					result.append("/");
				} else {
					result.append(URLEncoder.encode(String.valueOf(each), "UTF-8"));
				}
			}
			return result.toString();
		} catch (UnsupportedEncodingException e) {
			throw processException(e);
		}
	}
}