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。
