APP表情存入mysql数据库失败处理

一、问题

手机端APP添加表情后端报错，典型错误如下：

查看tomcat后台日志，核心报错信息如下： 
 Caused by: java.sql.SQLException: Incorrect string value: '\xF0\x9F\x98\x97\xF0\x9F...' for column 'CONTENT' at row 1
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1074)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4096)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:4028)
at com.mysql.jdbc.MysqlIO.sendCommand(MysqlIO.java:2490)
at com.mysql.jdbc.MysqlIO.sqlQueryDirect(MysqlIO.java:2651)
at com.mysql.jdbc.ConnectionImpl.execSQL(ConnectionImpl.java:2734)
at com.mysql.jdbc.PreparedStatement.executeInternal(PreparedStatement.java:2155)
at com.mysql.jdbc.PreparedStatement.execute(PreparedStatement.java:1379)
at org.apache.commons.dbcp.DelegatingPreparedStatement.execute(DelegatingPreparedStatement.java:172)
at org.apache.commons.dbcp.DelegatingPreparedStatement.execute(DelegatingPreparedStatement.java:172)
at com.ibatis.sqlmap.engine.execution.SqlExecutor.executeUpdate(SqlExecutor.java:80)
at com.ibatis.sqlmap.engine.mapping.statement.MappedStatement.sqlExecuteUpdate(MappedStatement.java:216)
at com.ibatis.sqlmap.engine.mapping.statement.MappedStatement.executeUpdate(MappedStatement.java:94)
... 46 more

二、问题原因

㈠ 原因
        普通的字符串或者表情都是占位3个字节，所以utf8足够用了，但是移动端的表情符号占位是4个字节，普通的utf8就不够用了，为了应对无线互联网的机遇和挑战、避免 emoji 表情符号带来的问题、涉及无线相关的 MySQL 数据库建议都提前采用 utf8mb4 字符集，这必须要作为移动互联网行业的一个技术选型的要点
    ㈡ 限制
        需要 >= MySQL 5.5.3版本、从库也必须是5.5的了、低版本不支持这个字符集、复制报错。

三、解决办法

1、修改mysql数据库字符为utf8mb4

修改数据库实例字符集

ALTER DATABASE database_name CHARACTER SET = utf8mb4 COLLATE = utf8mb4_unicode_ci;

相应表的字符集也需要重新修改

ALTER TABLE table_name CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

相应表字段的字符集也需要修改

ALTER TABLE table_name CHANGE column_name column_name VARCHAR(191) CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;

2、修改mysql配置参数

linux下修改/etc/my.cnf下新增以下内容

[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

修改好后重启下mysql

service mysql restart

查看数据库字符集

mysql -uroot -p

MariaDB [msjc]> show variables like '%char%';                                   +--------------------------+----------------------------+
| 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                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+

设置好之后，手机端就能正常保存表情字符了。

参考地址：https://mathiasbynens.be/notes/mysql-utf8mb4#utf8-to-utf8mb4