Filter：
 //接受字符转码
        String charset = config.getInitParameter("charset");
        if(charset == null){
            charset = "UTF-8";
        }
        request.setCharacterEncoding(charset);

web.xml:
 <filter>
        <filter-name>LoginFilter</filter-name>
        <filter-class>com.lxj.filter.LoginFilter</filter-class>
        <init-param>
            <param-name>charset</param-name>
            <param-value>UTF-8</param-value>
        </init-param>
    </filter>
    <filter-mapping>
        <filter-name>LoginFilter</filter-name>
        <url-pattern>/*</url-pattern>
    </filter-mapping>