MySQL 5.5连接器/J字符集编码(utf8mb4)问题

Question

根据文档，ConnectorJ应根据character_set_server变量自动检测字符编码...

然而，据我所知，它总是默认

设置名称latin1而不是设置名称utf8mb4

Sat Jul 06 15:45:20 CDT 2013 INFO: Profiler Event: [QUERY]  at java.sql.DriverManager.getConnection(DriverManager.java:579) duration: 1 ms, connection-id: 57, statement-id: 3, resultset-id: 4, message: /* mysql-connector-java-5.1.18 ( Revision: [e-mail]-20110930151701-jfj14ddfq48ifkfq ) */SHOW VARIABLES WHERE Variable_name ='language' OR Variable_name = 'net_write_timeout' OR Variable_name = 'interactive_timeout' OR Variable_name = 'wait_timeout' OR Variable_name = 'character_set_client' OR Variable_name = 'character_set_connection' OR Variable_name = 'character_set' OR Variable_name = 'character_set_server' OR Variable_name = 'tx_isolation' OR Variable_name = 'transaction_isolation' OR Variable_name = 'character_set_results' OR Variable_name = 'timezone' OR Variable_name = 'time_zone' OR Variable_name = 'system_time_zone' OR Variable_name = 'lower_case_table_names' OR Variable_name = 'max_allowed_packet' OR Variable_name = 'net_buffer_length' OR Variable_name = 'sql_mode' OR Variable_name = 'query_cache_type' OR Variable_name = 'query_cache_size' OR Variable_name = 'init_connect'
Sat Jul 06 15:45:20 CDT 2013 INFO: Profiler Event: [FETCH]  at java.sql.DriverManager.getConnection(DriverManager.java:579) duration: 0 ms, connection-id: 57, statement-id: 3, resultset-id: 4
Sat Jul 06 15:45:20 CDT 2013 INFO: Profiler Event: [QUERY]  at java.sql.DriverManager.getConnection(DriverManager.java:579) duration: 0 ms, connection-id: 57, statement-id: 3, resultset-id: 5, message: /* mysql-connector-java-5.1.18 ( Revision: [e-mail]-20110930151701-jfj14ddfq48ifkfq ) */SELECT @@session.auto_increment_increment
Sat Jul 06 15:45:20 CDT 2013 INFO: Profiler Event: [FETCH]  at java.sql.DriverManager.getConnection(DriverManager.java:579) duration: 0 ms, connection-id: 57, statement-id: 3, resultset-id: 5
Sat Jul 06 15:45:20 CDT 2013 INFO: Profiler Event: [QUERY]  at java.sql.DriverManager.getConnection(DriverManager.java:579) duration: 0 ms, connection-id: 57, statement-id: 4, resultset-id: 6, message: SHOW COLLATION
Sat Jul 06 15:45:20 CDT 2013 INFO: Profiler Event: [FETCH]  at java.sql.DriverManager.getConnection(DriverManager.java:579) duration: 3 ms, connection-id: 57, statement-id: 4, resultset-id: 6
Sat Jul 06 15:45:20 CDT 2013 INFO: Profiler Event: [QUERY]  at java.sql.DriverManager.getConnection(DriverManager.java:579) duration: 1 ms, connection-id: 57, statement-id: 999, resultset-id: 0, message: SET NAMES latin1

character_set_client        utf8
character_set_connection    utf8
character_set_results       utf8
character_set_server        utf8mb4

SET GLOBAL

SET

更新：当我更改my.cnf中的character_set_server值并重新启动我的服务器时，ConnectorJ检测到utf8mb4与预期的完全一样。

当我使用set GLOBAL手动设置值时，ConnectorJ继续使用latin1。

有人知道为什么会这样吗？有没有什么方法可以用ConnectorJ会检测到的方式更新字符集，而不必让mysql脱机呢？

Answer 1

我也有类似的问题。ConnectorJ的客户端字符集握手通常使用常规/不完整的UTF8字符集，而不是UTF8MB4

https://dev.mysql.com/doc/relNotes/connector-j/en/news-5-1-13.html

修正自5.1.12版以来发现的错误。连接器/J现在自动检测使用character_set_server=utf8mb4配置的服务器，或处理使用characterencoding=...传递的Java编码utf-8。正如SET names=中的utf8mb4在建立连接时所做的那样。（错误#54175)