遇到这个问题是在测试时发现用的是mysql，字符集为utf8，查到各路大神的办法，需要修改表的字符集为utf8mb4，但是试了很多次，无果~
于是尝试用java来实现，其实主要就是入库时用正则将表情转为字符，然后从库中取出时为string:

 1  /**
 2      * 将str中的emoji表情转为byte数组
 3      *
 4      * @param str
 5      * @return
 6      */
 7     public static String resolveToByteFromEmoji(String str) {
 8         Pattern pattern = Pattern
 9                 .compile("[^(\u2E80-\u9FFF\\w\\s`~!@#\\$%\\^&\\*\\(\\)_+-？（）——=\\[\\]{}\\|;。，、《》”：；“！……’:'\"<,>\\.?/\\\\*)]");
10         Matcher matcher = pattern.matcher(str);
11         StringBuffer sb2 = new StringBuffer();
12         while (matcher.find()) {
13             matcher.appendReplacement(sb2, resolveToByte(matcher.group(0)));
14         }
15         matcher.appendTail(sb2);
16         return sb2.toString();
17     }
18 
19     /**
20      * 将str中的byte数组类型的emoji表情转为正常显示的emoji表情
21      *
22      * @param str
23      * @return
24      */
25     public static String resolveToEmojiFromByte(String str) {
26         Pattern pattern2 = Pattern.compile("<:([[-]\\d*[,]]+):>");
27         Matcher matcher2 = pattern2.matcher(str);
28         StringBuffer sb3 = new StringBuffer();
29         while (matcher2.find()) {
30             matcher2.appendReplacement(sb3, resolveToEmoji(matcher2.group(0)));
31         }
32         matcher2.appendTail(sb3);
33         return sb3.toString();
34     }
35 
36     private static String resolveToByte(String str) {
37         byte[] b = str.getBytes();
38         StringBuffer sb = new StringBuffer();
39         sb.append("<:");
40         for (int i = 0; i < b.length; i++) {
41             if (i < b.length - 1) {
42                 sb.append(Byte.valueOf(b[i]).toString() + ",");
43             } else {
44                 sb.append(Byte.valueOf(b[i]).toString());
45             }
46         }
47         sb.append(":>");
48         return sb.toString();
49     }
50 
51     private static String resolveToEmoji(String str) {
52         str = str.replaceAll("<:", "").replaceAll(":>", "");
53         String[] s = str.split(",");
54         byte[] b = new byte[s.length];
55         for (int i = 0; i < s.length; i++) {
56             b[i] = Byte.valueOf(s[i]);
57         }
58         return new String(b);
59     }

因为表情都是有规律的，都是以<:开始:>结束~所以自然就有办法解决啦~~

————————————————
版权声明：本文为CSDN博主「wangdan199112」的原创文章，遵循CC 4.0 BY-SA版权协议，转载请附上原文出处链接及本声明。
原文链接：https://blog.csdn.net/wangdan199112/java/article/details/53290154