Javaweb过滤器Filter

public class CharacterEncodingFilter implements Filter {//导包javax.servlet.Filter
    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
        System.out.println("执行");
    }
    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
        servletRequest.setCharacterEncoding("UTF-8");
        servletResponse.setCharacterEncoding("UTF-8");
        servletResponse.setContentType("text/html;charset=UTF-8");
        filterChain.doFilter(servletRequest,servletResponse);//必须通过FilterChain调用doFilter之后过滤器才会生效
    }
    @Override
    public void destroy() {
        System.out.println("销毁");
    }
}