mysql存储emoji表情报错的处理方法【更改编码为utf8mb4】

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
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1073)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3593)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3525)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:1986)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2140)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2620)
at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1662)
at com.mysql.jdbc.StatementImpl.executeUpdate(StatementImpl.java:1581)

可以对4字节的字符进行编码存储，然后取出来的时候，再进行解码。但是这样做会使得任何使用该字符的地方都要进行编码与解码。

utf8mb4编码是utf8编码的超集，兼容utf8，并且能存储4字节的表情字符。
采用utf8mb4编码的好处是：存储与获取数据的时候，不用再考虑表情字符的编码与解码问题。

更改数据库的编码为utf8mb4:

1. MySQL的版本

utf8mb4的最低mysql版本支持版本为5.5.3+，若不是，请升级到较新版本。

2. MySQL驱动

5.1.34可用,最低不能低于5.1.13

3.修改MySQL配置文件

修改mysql配置文件my.cnf（windows为my.ini）

my.cnf一般在etc/mysql/my.cnf位置。找到后请在以下三部分里添加如下内容：

[client]
default-character-set = utf8mb4
[mysql]
default-character-set = utf8mb4
[mysqld]
character-set-client-handshake = FALSE
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci
init_connect='SET NAMES utf8mb4'

4. 重启数据库，检查变量

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	utf8
collation_connection	utf8mb4_unicode_ci
collation_database	utf8mb4_unicode_ci
collation_server	utf8mb4_unicode_ci

collation_connection 、collation_database 、collation_server是什么没关系。

但必须保证

系统变量	描述
character_set_client	(客户端来源数据使用的字符集)
character_set_connection	(连接层字符集)
character_set_database	(当前选中数据库的默认字符集)
character_set_results	(查询结果字符集)
character_set_server	(默认的内部操作字符集)

这几个变量必须是utf8mb4。

5. 数据库连接的配置

数据库连接参数中:

characterEncoding=utf8会被自动识别为utf8mb4，也可以不加这个参数，会自动检测。

而autoReconnect=true是必须加上的。

6. 将数据库和已经建好的表也转换成utf8mb4

更改数据库编码：

ALTER DATABASE caitu99 CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci;

更改表编码：

ALTER TABLE TABLE_NAME CONVERT TO CHARACTER SET utf8mb4 COLLATEutf8mb4_general_ci;

如有必要，还可以更改列的编码

7、在第3步设置character_set_database，character_set_server不成功的可以试下直接在mysql.exe下

set @@character_set_server='utf8mb4';
set @@character_set_database='utf8mb4';

# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.6/en/server-configuration-defaults.html
# *** DO NOT EDIT THIS FILE. It's a template which will be copied to the
# *** default location during install, and will be replaced if you
# *** upgrade to a newer version of MySQL.
[client]
default-character-set = utf8mb4
[mysql]
default-character-set = utf8mb4
[mysqld]
character-set-client-handshake = FALSE
character-set-server = utf8mb4
collation-server = utf8mb4_unicode_ci
init_connect='SET NAMES utf8mb4'
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
# These are commonly set, remove the # and set as required.
# basedir = .....
# datadir = .....
# port = .....
# server_id = .....
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES

这下数据库就可以存下emoji表情的编码了。

附上我的my.ini