JAVA 查找并移除字符串中的Emoji 😊

一、基础知识

Emoji 实际上是 UTF-8 (Unicode) 字符集上的特殊字符，多数基本 Emoji 都被分配到 Unicode 编码表 1 号平面的 U+1F300--1F6FF 和 U+1F900--1FAFF 两个区域，由2个字符组成。
肤色修饰：大多数与人相关的 Emoji 默认是黄色的，所以后来引入了五个新码点作为修饰符：U+1F3FB、U+1F3FC、U+1F3FD、U+1F3FE、U+1F3FF。肤色修饰符追加到现有的 Emoji 后形成新的样式： U+1F44B(👋 ) + U+1F3FD= 👋🏽
符号变体或组合：一个普通的字后连接一个或多个变体、组合标识(字符)，组合形成的 Emoji ： U+25C0+U+FE0F= ◀️ U+27A1+U+FE0F= ➡️ 1+U+FE0F+U+20E3= 1️⃣
国旗：每个国旗由2个地区标识符组合而成，地区标识符的对应码点范围为U+1F1E6~U+1F1FF，等同于2个指定范围的普通 Emoji 字符组成。 U+1F1E8+U+1F1F3= 🇨🇳
零宽度连接符（ZWJ）：多个基础 Emoji 通过零宽度连接符（U+200D）形成的复杂 Emoji： 👩+U+200D+🌾= 👩‍🌾 👩+U+200D+❤️‍+U+200D+👩= 👩‍❤️‍👩 👨+U+200D+❤️‍+U+200D+💋+U+200D+👨= 👨‍❤️‍💋‍👨
序列：一个基础 Emoji 加上多个标签字符 (U+E0020~ U+E007F )并以 Tag Cancel(U+E007)结尾，组合形成一个复杂 Emoji： U+1F3F4(🏴) +U+E0067+U+E0062+U+E0065+U+E006E+U+E0067+U+E007F= 🏴󠁧󠁢󠁥󠁮󠁧󠁿
特殊符号：特殊符号只有1个字符，有些符号在某些环境下会被当做Emoj处理：⏯、⏫、⏹;

Unicode 只是约定了码点到 emoji 的映射关系，并没有约定 Emoji 图形，每个 Emoji 字体文件可以按照自己的想法设计 Emoji。

二、解决方案

除了一些特殊符号形式的 Emoji，其他Emoji至少有2个字符，所以先根据第二个字符类型判断是否为Emoji，使用Character.UnicodeBlock.of和Character.getType方法判定每个字符的类型。
通过第二个字符类型判断当前2个字符为 Emoji 后： 1）判断是否有后续修饰 2）判断处理国旗类型；判断处理肤色修饰；判断处理 Emoji 序列标签；判断处理零宽度连接符；判断处理连续变体、组合标识；按照普通 Emoji 处理；
处理单字符的特殊符号，这一类型内有的属于 Emoji，有的不是，目前全部简单的按照普通 Emoji 处理；

三、完整代码

ini 复制代码

package com.zpf.tool;

import java.util.List;

public class EmojiUtil {

    public static boolean isEmojiNationalFlag(int codePoint) {
        return codePoint >= 127462 && codePoint <= 127487;
    }

    // String str = new String(new int[]{0x1F44B, 0x1F3FD}, 0, 2);
    public static boolean isEmojiSkinColor(int codePoint) {
        return codePoint >= 127995 && codePoint <= 127999;
    }

    // String str = new String(new int[]{0x1F3F4, 0xE0067, 0xE0062, 0xE0065, 0xE006E, 0xE0067, 0xE007F}, 0, 7);
    public static boolean isEmojiTagEnd(int codePoint) {
        return codePoint == 917631;
    }

    public static boolean isEmojiTagSpec(int codePoint) {
        return codePoint >= 917536 && codePoint <= 917630;
    }

    public static boolean isEmojiDecorateBlock(Character.UnicodeBlock block) {
        if (block == null) {
            return false;
        }
        return block.equals(Character.UnicodeBlock.VARIATION_SELECTORS)
                || block.equals(Character.UnicodeBlock.VARIATION_SELECTORS_SUPPLEMENT)
                || block.equals(Character.UnicodeBlock.COMBINING_HALF_MARKS)
                || block.equals(Character.UnicodeBlock.COMBINING_MARKS_FOR_SYMBOLS)
                || block.equals(Character.UnicodeBlock.COMBINING_DIACRITICAL_MARKS)
                || block.equals(Character.UnicodeBlock.COMBINING_DIACRITICAL_MARKS_SUPPLEMENT);
    }

    public static void pickAllEmoji(CharSequence data, StringBuilder removeResult, List<String> emojiList) {
        if (removeResult == null && emojiList == null) {
            return;
        }
        if (removeResult != null) {
            removeResult.delete(0, removeResult.length());
        }
        if (emojiList != null) {
            emojiList.clear();
        }
        if (data == null || data.length() == 0) {
            return;
        }
        StringBuilder emojiBuilder = new StringBuilder();
        int i = 0;
        int j;
        Character.UnicodeBlock block;
        while (i < data.length()) {
            if (i + 1 < data.length()) {
                block = Character.UnicodeBlock.of(data.charAt(i + 1));
                if (isEmojiDecorateBlock(block) || Character.UnicodeBlock.LOW_SURROGATES.equals(block)) {
                    if (i + 2 >= data.length()) {
                        emojiBuilder.append(data, i, i + 2);
                        break;
                    }
                    j = handleNationalFlag(data, i, emojiBuilder, emojiList);
                    if (i != j) {
                        i = j;
                        continue;
                    }
                    j = handleHumanSkin(data, i, emojiBuilder, emojiList);
                    if (i != j) {
                        i = j;
                        continue;
                    }
                    j = handleTagSequence(data, i, emojiBuilder, emojiList);
                    if (i != j) {
                        i = j;
                        continue;
                    }
                    emojiBuilder.append(data, i, i + 2);
                    i = handleNextChar(data, i + 2, emojiBuilder, emojiList);
                    continue;
                }
            }
            recordEmoji(emojiBuilder, emojiList);
            int type = Character.getType(data.charAt(i));
            if (type == (int) Character.OTHER_SYMBOL) {//特殊符号一律按照Emoji处理
                if (emojiList != null) {
                    emojiList.add(String.valueOf(data.charAt(i)));
                }
            } else if (removeResult != null) {
                removeResult.append(data.charAt(i));
            }
            i++;
        }
        recordEmoji(emojiBuilder, emojiList);
    }

    private static int handleNextChar(CharSequence data, int i, StringBuilder emojiBuilder, List<String> emojiList) {
        if (i >= data.length()) {
            return i;
        }
        char nextChar = data.charAt(i);
        if (nextChar == '\u200D') {//零宽度连接符
            emojiBuilder.append(nextChar);
            return i + 1;
        }
        int j = i;
        Character.UnicodeBlock block;
        while (j < data.length()) {
            nextChar = data.charAt(j);
            block = Character.UnicodeBlock.of(nextChar);
            if (isEmojiDecorateBlock(block)) {
                emojiBuilder.append(nextChar);
                j++;
            } else {
                break;
            }
        }
        if (i != j) {
            recordEmoji(emojiBuilder, emojiList);
        }
        return j;
    }

    private static int handleNationalFlag(CharSequence data, int i, StringBuilder emojiBuilder, List<String> emojiList) {
        int codePoint = Character.codePointAt(data, i);
        if (isEmojiNationalFlag(codePoint)) {//处理国旗类型
            recordEmoji(emojiBuilder, emojiList);//提交未处理
            if (i + 3 < data.length()) {
                codePoint = Character.codePointAt(data, i + 2);
                if (isEmojiNationalFlag(codePoint)) {
                    emojiBuilder.append(data, i, i + 4);
                    recordEmoji(emojiBuilder, emojiList);
                    i = i + 4;
                }
            }
            i = i + 2;
        }
        return i;
    }

    private static int handleHumanSkin(CharSequence data, int i, StringBuilder emojiBuilder, List<String> emojiList) {
        if (i + 3 >= data.length()) {
            return i;
        }
        int codePoint = Character.codePointAt(data, i + 2);
        if (isEmojiSkinColor(codePoint)) {//肤色修饰
            emojiBuilder.append(data, i, i + 4);
            recordEmoji(emojiBuilder, emojiList);
            i = i + 4;
        }
        return i;
    }

    private static int handleTagSequence(CharSequence data, int i, StringBuilder emojiBuilder, List<String> emojiList) {
        if (i + 3 >= data.length()) {
            return i;
        }
        int codePoint = Character.codePointAt(data, i + 2);
        if (isEmojiTagSpec(codePoint)) {
            emojiBuilder.append(data, i, i + 4);
            i = i + 4;
            while (i < data.length()) {
                codePoint = Character.codePointAt(data, i);
                if (isEmojiTagSpec(codePoint)) {
                    emojiBuilder.append(data, i, i + 2);
                    i = i + 2;
                } else if (isEmojiTagEnd(codePoint)) {
                    emojiBuilder.append(data, i, i + 2);
                    recordEmoji(emojiBuilder, emojiList);
                    i = i + 2;
                    break;
                } else { //error
                    break;
                }
            }
            emojiBuilder.delete(0, emojiBuilder.length());
        } else if (isEmojiTagEnd(codePoint)) {
            emojiBuilder.append(data, i, i + 4);
            recordEmoji(emojiBuilder, emojiList);
            i = i + 4;
        }
        return i;
    }

    private static void recordEmoji(StringBuilder builder, List<String> emojiList) {
        if (builder != null && builder.length() > 0) {
            if (emojiList != null) {
                emojiList.add(builder.toString());
            }
            builder.delete(0, builder.length());
        }
    }

}