今天遇到一堆MySQL 中文乱码的问题 ，总体来说分为数据库层面，Tomcat层面，web表示层面。

数据库层面

先是MySQL数据库中文乱码问题，大概样子如下：

然后自我感觉这件事情不就是改下字段的编码吗，那就改一下呗
如图，我更改了Encoding

然后发现事情并没有那简单，于是开始上网查解决方案，网上说需要修改/etc/my.cnf(此配置文件对于mac后缀是.cnf，对于Windows是.ini)。所以漫漫找寻之路开始了，最后连Linux查询find语句也试了就是找不到，终于在几篇文章里查到Mac上的MySQL没有my.cnf配置文件，好吧，继续寻找解决方案，有人说MySQL下的support-file中找一个.cnf复制一下再改；里面的东西，然而我连.cnf文件都没有找到。最后采用一位网友的办法，直接在/etc目录下 vim my.cnf新建一个文件，在此附上我修改过的文件里面内容，在[mysqld] 之后增加了一行 collation-server = utf8_general_ci

# Example MySQL config file for medium systems.
  #
  # This is for a system with little memory (32M - 64M) where MySQL plays
  # an important part, or systems up to 128M where MySQL is used together with
  # other programs (such as a web server)
  #
  # MySQL programs look for option files in a set of
  # locations which depend on the deployment platform.
  # You can copy this option file to one of those
  # locations. For information about these locations, see:
  # http://dev.mysql.com/doc/mysql/en/option-files.html
  #
  # In this file, you can use all long options that a program supports.
  # If you want to know which options a program supports, run the program
  # with the "--help" option.
  # The following options will be passed to all MySQL clients
  [client]
  default-character-set=utf8
  #password   = your_password
  port        = 3306
  socket      = /tmp/mysql.sock
  # Here follows entries for some specific programs
  # The MySQL server
  [mysqld]
  character-set-server=utf8
  default-storage-engine = INNODB
  collation-server = utf8_general_ci
  init_connect='SET NAMES utf8'
  port        = 3306
  socket      = /tmp/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
  character-set-server=utf8
  init_connect='SET NAMES utf8'
# Don't listen on a TCP/IP port at all. This can be a security enhancement,
# if all processes that need to connect to mysqld run on the same host.
# All interaction with mysqld must be made via Unix sockets or named pipes.
# Note that using this option without enabling named pipes on Windows
# (via the "enable-named-pipe" option) will render mysqld useless!
#
#skip-networking

  # Replication Master Server (default)
  # binary logging is required for replication
  log-bin=mysql-bin

    # binary logging format - mixed recommended
    binlog_format=mixed

      # required unique id between 1 and 2^32 - 1
      # defaults to 1 if master-host is not set
      # but will not function as a master if omitted
      server-id   = 1

    # Replication Slave (comment out master section to use this)
    #
    # To configure this host as a replication slave, you can choose between
    # two methods :
    #
    # 1) Use the CHANGE MASTER TO command (fully described in our manual) -
    #    the syntax is:
    #
    #    CHANGE MASTER TO MASTER_HOST=<host>, MASTER_PORT=<port>,
    #    MASTER_USER=<user>, MASTER_PASSWORD=<password> ;
    #
    #    where you replace <host>, <user>, <password> by quoted strings and
    #    <port> by the master's port number (3306 by default).
    #
    #    Example:
    #
    #    CHANGE MASTER TO MASTER_HOST='125.564.12.1', MASTER_PORT=3306,
    #    MASTER_USER='joe', MASTER_PASSWORD='secret';
    #
    # OR
    #
    # 2) Set the variables below. However, in case you choose this method, then
    #    start replication for the first time (even unsuccessfully, for example
    #    if you mistyped the password in master-password and the slave fails to
    #    connect), the slave will create a master.info file, and any later
    #    change in this file to the variables' values below will be ignored and
    #    overridden by the content of the master.info file, unless you shutdown
    #    the slave server, delete master.info and restart the slaver server.
    #    For that reason, you may want to leave the lines below untouched
    #    (commented) and instead use CHANGE MASTER TO (see above)
    #
    # required unique id between 2 and 2^32 - 1
    # (and different from the master)
    # defaults to 2 if master-host is set
    # but will not function as a slave if omitted
    #server-id       = 2
    #
    # The replication master for this slave - required
    #master-host     =   <hostname>
    #
    # The username the slave will use for authentication when connecting
    # to the master - required
    #master-user     =   <username>
    #
    # The password the slave will authenticate with when connecting to
    # the master - required
    #master-password =   <password>
    #
    # The port the master is listening on.
    # optional - defaults to 3306
    #master-port     =  <port>
    #
    # binary logging - not required for slaves, but recommended
    #log-bin=mysql-bin

      # Uncomment the following if you are using InnoDB tables
      #innodb_data_home_dir = /usr/local/mysql/data
      #innodb_data_file_path = ibdata1:10M:autoextend
      #innodb_log_group_home_dir = /usr/local/mysql/data
      # You can set .._buffer_pool_size up to 50 - 80 %
      # of RAM but beware of setting memory usage too high
      #innodb_buffer_pool_size = 16M
      #innodb_additional_mem_pool_size = 2M
      # Set .._log_file_size to 25 % of buffer pool size
      #innodb_log_file_size = 5M
      #innodb_log_buffer_size = 8M
      #innodb_flush_log_at_trx_commit = 1
      #innodb_lock_wait_timeout = 50

        [mysqldump]
        quick
        max_allowed_packet = 16M

          [mysql]
          no-auto-rehash
          # Remove the next comment character if you are not familiar with SQL
          #safe-updates
          default-character-set=utf8

        [myisamchk]
        key_buffer_size = 20M
        sort_buffer_size = 20M
        read_buffer = 2M
        write_buffer = 2M

          [mysqlhotcopy]
          interactive-timeout

此时保存文件，再修改文件读写权限，将权限修改为664

sudo chmod 664 /etc/my.cnf

之后再重启MySQL和配置文件就可以生效了。
然后完成之后，确实，如果你查一下MySQL的各种编码，确实都变成了UTF-8
通过以下命令

然而~输入不了中文了，报错

---

最后将当前数据库以及所有表所有字段都设置为UTF-8

惊喜的发现可以愉快的输入中文了~~
至此，数据库层面告一段落

---

Tomcat层面

接下来我说的简略一些，如果URL请求采取GET方法，那么你的URL中可能会出现中文，所以需要在Tomcat配置文件里面设置编码方式。

修改Tomcat下的conf/server.xml文件，找到如下代码：

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

这段代码规定了Tomcat监听HTTP请求的端口号等信息。可以在这里添加一个属性：URIEncoding，将该属性值设置为UTF-8，
即可让Tomcat（默认ISO-8859-1编码）以UTF-8的编码处理get请求。更改后的代码如下所示：

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

---

Web显示层面

这里主要针对请求为POST方法的时候，你需要设置web.xml 文件，设置字符串过滤器

<filter>
   <filter-name>characterEncodingFilter</filter-name>
   <filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
   <init-param>
       <param-name>encoding</param-name>
       <param-value>UTF-8</param-value>
   </init-param>
   <init-param>
       <param-name>forceEncoding</param-name>
       <param-value>true</param-value>
   </init-param>
</filter>
<filter-mapping>
   <filter-name>characterEncodingFilter</filter-name>
   <url-pattern>/*</url-pattern>
</filter-mapping>

最后如果你要回显到页面上打印中文的话需要设置一下response
如果你使用springMVC可以设置

@RequestMapping(value = "/XX.do", produces="text/html;charset=UTF-8")