<filter>
와 <filter-mapping>
를 써야해요
<filter>
<filter-name>Set Character Encoding</filter-name>
<filter-class>org.apache.catalina.filters.SetCharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>utf-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>Set Character Encoding</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
이렇게 이제 쓰면 doPost( )메소드를 실행할 때마다
request.setCharacterEncoding("UTF-8");
을 안써도 된다.
❗중요
/*
: 모든 요청 원리