java - 为什么 java 字符串在 MYSQL 中没有保存为 UTF-8？

Question

message = new String(("round " + id).getBytes("UTF-8"));

conn = DriverManager.getConnection("jdbc:mysql://" + host + "/" + db + "?useUnicode=true&characterEncoding=UTF-8&"
              + "user=" + login + "&password=" + password);

当我插入编码为UTF-8 CI的数据库时，得到类似这样的内容������������������ ���� 179，java文件编码是utf-8，我哪里做错了？

+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | utf8                       |
| character_set_connection | utf8                       |
| character_set_database   | utf8                       |
| character_set_filesystem | binary                     |
| character_set_results    | utf8                       |
| character_set_server     | utf8                       |
| character_set_system     | utf8                       |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+

Answer 1

通常，MySQL 带有一个预定义的系统变量列表。如果要列出它们，可以打开 MySQL 提示符并键入:

mysql> SHOW VARIABLES LIKE  'char%';
+--------------------------+----------------------------+
| Variable_name            | Value                      |
+--------------------------+----------------------------+
| character_set_client     | latin1                     |
| character_set_connection | latin1                     |
| character_set_database   | latin1                     |
| character_set_filesystem | binary                     |
| character_set_results    | latin1                     |
| character_set_server     | latin1                     |
| character_set_system     | latin1                     |
| character_sets_dir       | /usr/share/mysql/charsets/ |
+--------------------------+----------------------------+

如图所示，MySQL的默认编码是latin1。为了更改它，您需要稍微编辑一下您的 my.cnf 文件并添加以下行:

[client]
default-character-set=utf8

[mysql]
default-character-set=utf8


[mysqld]
collation-server = utf8_unicode_ci
init-connect='SET NAMES utf8'
character-set-server = utf8

当您配置my.cnf 文件并重新启动MySQL 服务器时，您会注意到不同之处。

编辑: 您可以像这样为 JDBC 的 DriverManager 设置编码:

DriverManager.getConnection("jdbc:mysql://" + host + "/" + db + "?useUnicode=true&"
              + "user=" + login + "&password=" + password + "&characterEncoding=utf8");