EncodingKit.java

/**
 * Copyright (c) 2015-2016, BruceZCQ (zcq@zhucongqi.cn).
 *
 * 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.jfinal.ext2.kit;

import java.io.UnsupportedEncodingException;

/**
 * @author BruceZCQ
 *
 */
final public class EncodingKit {

	/** 7位ASCII字符，也叫作ISO646-US、Unicode字符集的基本拉丁块 */
	public static final String US_ASCII = "US-ASCII";

	/** ISO 拉丁字母表 No.1，也叫作 ISO-LATIN-1 */
	public static final String ISO_8859_1 = "ISO-8859-1";

	/** 8 位 UCS 转换格式 */
	public static final String UTF_8 = "UTF-8";

	/** 16 位 UCS 转换格式，Big Endian（最低地址存放高位字节）字节顺序 */
	public static final String UTF_16BE = "UTF-16BE";

	/** 16 位 UCS 转换格式，Little-endian（最高地址存放低位字节）字节顺序 */
	public static final String UTF_16LE = "UTF-16LE";

	/** 16 位 UCS 转换格式，字节顺序由可选的字节顺序标记来标识 */
	public static final String UTF_16 = "UTF-16";

	/** 中文超大字符集 */
	public static final String GBK = "GBK";

	/**
	 * 将字符编码转换成US-ASCII码
	 */
	public static String toASCII(String str) {
		return changeCharset(str, US_ASCII);
	}

	/**
	 * 将字符编码转换成ISO-8859-1码
	 */
	public static String toISO_8859_1(String str) {
		return changeCharset(str, ISO_8859_1);
	}

	/**
	 * 将字符编码转换成UTF-8码
	 */
	public static String toUTF_8(String str){
		return changeCharset(str, UTF_8);
	}

	/**
	 * 将字符编码转换成UTF-16BE码
	 */
	public static String toUTF_16BE(String str) {
		return changeCharset(str, UTF_16BE);
	}

	/**
	 * 将字符编码转换成UTF-16LE码
	 */
	public static String toUTF_16LE(String str) {
		return changeCharset(str, UTF_16LE);
	}

	/**
	 * 将字符编码转换成UTF-16码
	 */
	public static String toUTF_16(String str) {
		return changeCharset(str, UTF_16);
	}

	/**
	 * 将字符编码转换成GBK码
	 */
	public static String toGBK(String str) {
		return changeCharset(str, GBK);
	}

	/**
	 * 字符串编码转换的实现方法
	 * 
	 * @param str
	 *            待转换编码的字符串
	 * @param newCharset
	 *            目标编码
	 * @return
	 */
	public static String changeCharset(String str, String newCharset) {
		if (str != null) {
			// 用默认字符编码解码字符串。
			byte[] bs = str.getBytes();
			// 用新的字符编码生成字符串
			try {
				return new String(bs, newCharset);
			} catch (UnsupportedEncodingException e) {}
		}
		return "";
	}

	/**
	 * 字符串编码转换的实现方法
	 * 
	 * @param str
	 *            待转换编码的字符串
	 * @param oldCharset
	 *            原编码
	 * @param newCharset
	 *            目标编码
	 * @return
	 */
	public static String changeCharset(String str, String oldCharset, String newCharset) {
		if (str != null) {
			try {
				// 用旧的字符编码解码字符串。解码可能会出现异常。
				byte[] bs = str.getBytes(oldCharset);
				// 用新的字符编码生成字符串
				return new String(bs, newCharset);
			} catch (UnsupportedEncodingException e) {
			}
		}
		return "";
	}
}