jdbc连接mysql报null问题解决

<!-- 统一编码 --> <filter> <filter-name>charsetEncoding</filter-name> <filter-class></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>charsetEncoding</filter-name> <url-pattern>/*</url-pattern> </filter-mapping>