MySQL emoji支持

概述

utf-8编码可能2个字节、3个字节、4个字节的字符，但是MySQL的utf8编码只支持3字节的数据，而移动端的表情数据是4个字节的字符。如果直接往采用utf-8编码的数据库中插入表情数据，Java程序中将报SQL异常：

java.sql.SQLException: Incorrect string value: ‘\xF0\x9F\x92\x94’ for column ‘name’ at row 1

针对该问题处理最简单的方式是更改数据库的编码为utf8mb4，直接将问题扼杀在摇篮中。

前置条件

• MySQL服务器版本不能低于5.5.3;
• MySQL驱动版本不能低于5.1.13;

my.cnf

[client] 
default-character-set = utf8mb4 
[mysql] 
default-character-set = utf8mb4 
[mysqld] 
character-set-client-handshake = FALSE 
character-set-server = utf8mb4 
collation-server = utf8mb4_general_ci 
init_connect='SET NAMES utf8mb4'

重启数据库。

检查数据库变量

SHOW VARIABLES WHERE Variable_name LIKE 'character_set_%' OR Variable_name LIKE 'collation%';

Variable_name	Value
character_set_client	utf8mb4
character_set_connection	utf8mb4
character_set_database	utf8mb4
character_set_filesystem	binary
character_set_results	utf8mb4
character_set_server	utf8mb4
character_set_system	utf8mb4
collation_connection	utf8mb4_general_ci
collation_database	utf8mb4_general_ci
collation_server	utf8mb4_general_ci

更改现有数据库、表、字段编码

ALTER DATABASE `ticketdb` CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;
ALTER TABLE `ticket_description` CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;
ALTER TABLE `ticket_description`
MODIFY COLUMN `description`  text CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NULL COMMENT '工单描述' AFTER `id`;

如此一来，emoji表情应该不是问题了。