彻底解决乱码问题JAVA

真是很有用的一篇文章，转自：http://xupo.iteye.com/blog/1135891，解决了我的数据库乱码问题，其它还没有试过，保留下来。

每次做中文项目时，必定会遇到的一个问题，就是中文显示乱码问题，每次的解决方式都不太相同。 这次将GK项目过程中遇到乱码问题及解决方式记录下来，以备忘。 乱码的可以有多个环节，如页面提交到tomcat乱码，tomcat到数据库乱码，数据库提取显示乱码。

一、页面提交到tomcat乱码 解决方法是在tomcat/conf/server.xml中进行配置， 以tomcat6.0.32为例，需将以下代码：

<Connectorport="8080"protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443"/>

<Connector port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" />

 

改为：

<Connectorport="8080"protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443"URIEncoding="UTF-8"/>

<Connector port="8080" protocol="HTTP/1.1"
               connectionTimeout="20000"
               redirectPort="8443" URIEncoding="UTF-8" />

 

如果tomcat前端有Apache或是Nginx转发，则还需将：

<Connectorport="8009"protocol="AJP/1.3"redirectPort="8443"/>

<Connector port="8009" protocol="AJP/1.3" redirectPort="8443" />

 

改为：

<Connectorport="8009"protocol="AJP/1.3"redirectPort="8443"URIEncoding="UTF-8"/>

<Connector port="8009" protocol="AJP/1.3" redirectPort="8443" URIEncoding="UTF-8" />

 

二、tomcat到数据库乱码 如果通过tomcat远程调试，发现tomcat端接受到的数据不乱码，入库后乱码，则有可能是数据库设置造成的（同时也要检查操作系统

的字符集）。 对于Mysql数据库不同的版本配置也不一样。 安装完数据库后，登录数据库，通过如下命令查看，看数据库的字符集是否正确：

 

mysql> show variables like 'collation_%';
+----------------------+-----------------+
| Variable_name        | Value           |
+----------------------+-----------------+
| collation_connection | utf8_general_ci |
| collation_database   | utf8_general_ci |
| collation_server     | utf8_general_ci |
+----------------------+-----------------+
3 rows in set (0.00 sec)
mysql> show variables like 'character_set_%';
+--------------------------+----------------------------+
| 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/ |
+--------------------------+----------------------------+

mysql> show variables like 'collation_%';
+----------------------+-----------------+
| Variable_name        | Value           |
+----------------------+-----------------+
| collation_connection | utf8_general_ci |
| collation_database   | utf8_general_ci |
| collation_server     | utf8_general_ci |
+----------------------+-----------------+
3 rows in set (0.00 sec)
mysql> show variables like 'character_set_%';
+--------------------------+----------------------------+
| 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/ |
+--------------------------+----------------------------+

 

如果不是像上面显示的那样，则需要设置数据库的字符集。步骤如下： 查找安装完成后的数据库cnf文件

#find / -name *.cnf
/usr/share/mysql/my-large.cnf
/usr/share/mysql/my-small.cnf
/usr/share/mysql/my-innodb-heavy-4G.cnf
/usr/share/mysql/my-medium.cnf
/usr/share/mysql/my-huge.cnf
#cp /usr/share/mysql/my-medium.cnf /etc/my.cnf
#vim /etc/my.cnf

#find / -name *.cnf
/usr/share/mysql/my-large.cnf
/usr/share/mysql/my-small.cnf
/usr/share/mysql/my-innodb-heavy-4G.cnf
/usr/share/mysql/my-medium.cnf
/usr/share/mysql/my-huge.cnf
#cp /usr/share/mysql/my-medium.cnf /etc/my.cnf
#vim /etc/my.cnf

 

在[client]下增加default-character-set=utf8 在[mysqld]下增加character_set_server=utf8

一定注意，这里不是default-character-set=utf8（对于5.5以前的版本应该写

default-character-set=utf8, 5.5以后必须写character_set_server=utf8,否则无效

设置完时内容如下：（注：这里的其他数值未根据实际情况修改）

[client]
#password       = your_password
port            = 3306
socket          = /var/lib/mysql/mysql.sock
default-character-set=utf8

# Here follows entries for some specific programs

# The MySQL server
[mysqld]
character_set_server=utf8
port            = 3306
socket          = /var/lib/mysql/mysql.sock
skip-external-locking
key_buffer_size = 16M
max_allowed_packet = 1M
table_open_cache = 64
sort_buffer_size = 512K
net_buffer_length = 8K
read_buffer_size = 256K
read_rnd_buffer_size = 512K
myisam_sort_buffer_size = 8M

[client]
#password       = your_password
port            = 3306
socket          = /var/lib/mysql/mysql.sock
default-character-set=utf8

# Here follows entries for some specific programs

# The MySQL server
[mysqld]
character_set_server=utf8
port            = 3306
socket          = /var/lib/mysql/mysql.sock
skip-external-locking
key_buffer_size = 16M
max_allowed_packet = 1M
table_open_cache = 64
sort_buffer_size = 512K
net_buffer_length = 8K
read_buffer_size = 256K
read_rnd_buffer_size = 512K
myisam_sort_buffer_size = 8M

 

修改完成后，可以通过以下命令重启mysql:

#/etc/init.d/mysql restart

#/etc/init.d/mysql restart

 

如果在重启过程中看到如下错误信息：

Can’t connect to local MySQL server through socket ‘/var/lib/mysql/mysql.sock’

 

或是其他类似The server quit without updating PID file 之类的错误，都可以通过进一步查看详细错误信息：

#more /var/lib/mysql/...err

#more /var/lib/mysql/...err

 

也许你会看到类似如下的错误信息：

unknown variable 'default-character-set=utf8'

 

这说明/etc/my.cnf配置出错了。 所以并不是/var/lib/mysql/mysql.sock不存在造成的，如果/etc/my.cnf正确无误， 则执行/etc/init.d/mysql restart的时候mysql.sock会自动生成的，mysql.sock无法查看，无法修改，即便是用root用户。 此时就要检查/etc/my.cnf设置是否正确，比如上文提到过的mysql不同版本对于[mysqld]节点的字符集设置是default-character-

set=utf8还是character_set_server=utf8，这是不一样的。 正确设置后，再运行/etc/init.d/mysql restart，提示成功，系统会自动在/var/lib/mysql下生成一个mysql.sock文件。 此时再进入到mysql中，通过 show variables like 'collation_%';和show variables like 'character_set_%';结果是否正确。

有时候，在linux SHELL中输入mysql会有类似mysql无法识别OS Characterset GB18030，

mysql: Unknown OS character set 'GB18030'. mysql: Switching to the default character set 'latin1'.

 

采用默认的latin1之类的信息，表明操作系统的编码设置需要修改，描述如下： 查看操作系统的字符集

#locale
LANG=utf8
LC_CTYPE="utf8"
LC_NUMERIC="utf8"
LC_TIME="utf8"
LC_COLLATE="utf8"
LC_MONETARY="utf8"
LC_MESSAGES="utf8"
LC_PAPER="utf8"
LC_NAME="utf8"
LC_ADDRESS="utf8"
LC_TELEPHONE="utf8"
LC_MEASUREMENT="utf8"
LC_IDENTIFICATION="utf8"
LC_ALL=

#locale
LANG=utf8
LC_CTYPE="utf8"
LC_NUMERIC="utf8"
LC_TIME="utf8"
LC_COLLATE="utf8"
LC_MONETARY="utf8"
LC_MESSAGES="utf8"
LC_PAPER="utf8"
LC_NAME="utf8"
LC_ADDRESS="utf8"
LC_TELEPHONE="utf8"
LC_MEASUREMENT="utf8"
LC_IDENTIFICATION="utf8"
LC_ALL=

 

如果不是这样，则需要对操作系统字符集进行修改：

#vim /etc/syconfig/i18n

#vim /etc/syconfig/i18n

 

修改成：LANG="zh_CN.UTF-8"即可 另外，再查看一下环境变量的设置

#vim /etc/profile

#vim /etc/profile

 

里面可以没有字符集的设置，如果有，应类似如下设置：

export LC_ALL="C" #export LANG="zh_CN.UTF-8"

 

设置完成后，

#source /etc/profile

#source /etc/profile

 

使环境变量生效，如果不放心，可以reboot

三、hibernate设置 如果hibernate中文乱码，可以尝试在persistence.xml中增加 hibernate配置文件中,加上属性

<propertyname="connection.useUnicode">true</property>
<propertyname="connection.characterEncoding">UTF-8</property>

<property name="connection.useUnicode">true</property> 
<property name="connection.characterEncoding">UTF-8</property>

 

URL连接可以设置成：jdbc:mysql://localhost:3306/workshopdb?useUnicode=true&characterEncoding=UTF-8(如果其他方式能解决

乱码，就不这么设置）

乱码的可能性还很多，具体问题还得具体分析。

 

补充、数据库相关

如果要通过命令创建UTF-8格式的数据库，需通过如下方式：

CREATEDATABASE `test2` DEFAULTCHARACTERSET utf8 COLLATE utf8_general_ci

CREATE DATABASE `test2` DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci

 

如果是GBK，则用

createdatabase test2 DEFAULTCHARACTERSET gbk COLLATE gbk_chinese_ci;）

create database test2 DEFAULT CHARACTER SET gbk COLLATE gbk_chinese_ci;）

 

如果需要为Mysql增加用户

 

shell> mysql --user=root mysql
mysql> GRANT ALL PRIVILEGES ON *(or DBName).* TO monty@localhost
IDENTIFIED BY 'something' WITH GRANT OPTION;
mysql> GRANT ALL PRIVILEGES ON *(or DBName).* TO monty@"%"
IDENTIFIED BY 'something' WITH GRANT OPTION;
mysql> GRANT RELOAD,PROCESS ON *(or DBName).* TO admin@localhost;
mysql> GRANT USAGE ON *.* TO dummy@localhost