Java处理emoji

package com.mojxtang;

import org.apache.commons.lang3.StringUtils;

/**
 * <pre>
 * 本类的主要功能是将带有emoji的字符串，格式化成unicode字符串，并且提供可见unicode字符反解成emoji字符
 *  
 * 
 * 相关识知点：
 * <b>
 * Unicode平面，
 * BMP的字符可以使用charAt(index)来处理,计数可以使用length()
 * 其它平面字符，需要用codePointAt(index),计数可以使用codePointCount(0,str.lenght())</b>
 * 
 * Unicode可以逻辑分为17平面（Plane），每个平面拥有65536（ = 216）个代码点，虽然目前只有少数平面被使
 * 用。
 * 平面0 (0000–FFFF): 基本多文种平面（Basic Multilingual Plane, BMP）.
 * 平面1 (10000–1FFFF): 多文种补充平面（Supplementary Multilingual Plane, SMP）.
 * 平面2 (20000–2FFFF): 表意文字补充平面（Supplementary Ideographic Plane, SIP）.
 * 平面3 (30000–3FFFF): 表意文字第三平面（Tertiary Ideographic Plane, TIP）.
 * 平面4 to 13 (40000–DFFFF)尚未使用
 * 平面14 (E0000–EFFFF): 特别用途补充平面（Supplementary Special-purpose Plane, SSP）
 * 平面15 (F0000–FFFFF)保留作为私人使用区（Private Use Area, PUA）
 * 平面16 (100000–10FFFF)，保留作为私人使用区（Private Use Area, PUA）
 * 
 * 参考：
 * 百度百科: https://baike.baidu.com/item/emoji/8154456?fr=aladdin
*emoji表情:http://www.fhdq.net/emoji/emojifuhao.html
 * 杂项象形符号:1F300-1F5FF
 * 表情符号：1F600-1F64F
 * 交通和地图符号:1F680-1F6FF
 * 杂项符号：2600-26FF
 * 符号字体:2700-27BF
 * 国旗：1F100-1F1FF
 * 箭头：2B00-2BFF 2900-297F
 * 各种技术符号：2300-23FF
 * 字母符号: 2100–214F
 * 中文符号： 303D 3200–32FF 2049 203C
 *  Private Use Area:E000-F8FF;
 *  High Surrogates D800..DB7F; 
 *  High Private Use Surrogates  DB80..DBFF
 *  Low Surrogates DC00..DFFF  D800-DFFF E000-F8FF
 *  标点符号：2000-200F 2028-202F 205F 2065-206F
 *  变异选择器：IOS独有 FE00-FE0F
 * </pre>
 */
public class EmojiCharacterUtil {

	// 转义时标识
	private static final char unicode_separator = '&';
	private static final char unicode_prefix = 'u';
	private static final char separator = ':';

	private static boolean isEmojiCharacter(int codePoint) {
		return (codePoint >= 0x2600 && codePoint <= 0x27BF) // 杂项符号与符号字体
				|| codePoint == 0x303D || codePoint == 0x2049 || codePoint == 0x203C
				|| (codePoint >= 0x2000 && codePoint <= 0x200F)//
				|| (codePoint >= 0x2028 && codePoint <= 0x202F)//
				|| codePoint == 0x205F //
				|| (codePoint >= 0x2065 && codePoint <= 0x206F)//
				/* 标点符号占用区域 */
				|| (codePoint >= 0x2100 && codePoint <= 0x214F)// 字母符号
				|| (codePoint >= 0x2300 && codePoint <= 0x23FF)// 各种技术符号
				|| (codePoint >= 0x2B00 && codePoint <= 0x2BFF)// 箭头A
				|| (codePoint >= 0x2900 && codePoint <= 0x297F)// 箭头B
				|| (codePoint >= 0x3200 && codePoint <= 0x32FF)// 中文符号
				|| (codePoint >= 0xD800 && codePoint <= 0xDFFF)// 高低位替代符保留区域
				|| (codePoint >= 0xE000 && codePoint <= 0xF8FF)// 私有保留区域
				|| (codePoint >= 0xFE00 && codePoint <= 0xFE0F)// 变异选择器
				|| codePoint >= 0x10000; // Plane在第二平面以上的，char都不可以存，全部都转
	}

	/**
	 * 将带有emoji字符的字符串转换成可见字符标识
	 */
	public static String escape(String src) {
		if (StringUtils.isBlank(src)) {
			return src;
		}
		int cpCount = src.codePointCount(0, src.length());
		int firCodeIndex = src.offsetByCodePoints(0, 0);
		int lstCodeIndex = src.offsetByCodePoints(0, cpCount - 1);
		StringBuilder sb = new StringBuilder(src.length());
		for (int index = firCodeIndex; index <= lstCodeIndex; index++) {
			int codepoint = src.codePointAt(index);
			if (isEmojiCharacter(codepoint)) {
				String hash = Integer.toHexString(codepoint);
				sb.append(unicode_separator).append(hash.length()).append(unicode_prefix).append(separator)
						.append(hash);
				// hash 长度，4位1个字节
				index += (hash.length() - 1) / 4;
			} else {
				sb.append((char) codepoint);
			}
		}
		return sb.toString();
	}

	/** 解析可见字符标识字符串 */
	public static String reverse(String src) {
		// 查找对应编码的标识位
		if (StringUtils.isBlank(src)) {
			return src;
		}
		StringBuilder sb = new StringBuilder(src.length());
		char[] sourceChar = src.toCharArray();
		int index = 0;
		while (index < sourceChar.length) {
			if (sourceChar[index] == unicode_separator) {
				if (index + 6 >= sourceChar.length) {
					sb.append(sourceChar[index]);
					index++;
					continue;
				}
				// 自已的格式，与通用unicode格式不能互转
				if (sourceChar[index + 1] >= '4' && sourceChar[index + 1] <= '6'
						&& sourceChar[index + 2] == unicode_prefix && sourceChar[index + 3] == separator) {
					int length = Integer.parseInt(String.valueOf(sourceChar[index + 1]));
					char[] hexchars = new char[length]; // 创建一个4至六位的数组，来存储uncode码的HEX值
					for (int j = 0; j < length; j++) {
						char ch = sourceChar[index + 4 + j];// 4位识别码
						if ((ch >= '0' && ch <= '9') || (ch >= 'a' && ch <= 'f')) {
							hexchars[j] = ch;

						} else { // 字符范围不对
							sb.append(sourceChar[index]);
							index++;
							break;
						}
					}
					sb.append(Character.toChars(Integer.parseInt(new String(hexchars), 16)));
					index += (4 + length);// 4位前缀+4-6位字符码
				} else if (sourceChar[index + 1] == unicode_prefix) { // 通用字符的反转
					// 因为第二平面之上的，已经采用了我们自己转码格式，所以这里是固定的长度4
					char[] hexchars = new char[4];
					for (int j = 0; j < 4; j++) {
						char ch = sourceChar[index + 2 + j]; // 两位识别码要去掉
						if ((ch >= '0' && ch <= '9') || (ch >= 'a' && ch <= 'f')) {
							hexchars[j] = ch; // 4位识别码
						} else { // 字符范围不对
							sb.append(sourceChar[index]);
							index++;
							break;
						}
						sb.append(Character.toChars(Integer.parseInt(String.valueOf(hexchars), 16)));
						index += (2 + 4);// 2位前缀+4位字符码
					}
				} else {
					sb.append(sourceChar[index]);
					index++;
					continue;
				}
			} else {
				sb.append(sourceChar[index]);
				index++;
				continue;
			}
		}

		return sb.toString();
	}

	public static String filter(String src) {
		if (src == null) {
			return null;
		}
		int cpCount = src.codePointCount(0, src.length());
		int firCodeIndex = src.offsetByCodePoints(0, 0);
		int lstCodeIndex = src.offsetByCodePoints(0, cpCount - 1);
		StringBuilder sb = new StringBuilder(src.length());
		for (int index = firCodeIndex; index <= lstCodeIndex;) {
			int codepoint = src.codePointAt(index);
			if (!isEmojiCharacter(codepoint)) {
				System.err.println("codepoint:" + Integer.toHexString(codepoint));
				sb.append((char) codepoint);
			}
			index += ((Character.isSupplementaryCodePoint(codepoint)) ? 2 : 1);

		}
		return sb.toString();
	}
}