過濾器

@WebFilter("/*")
public class File implements Filter {
public void init(FilterConfig filterConfig) throws ServletException {
System.out.println("初始化過濾器");
}

public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain filterChain) throws IOException, ServletException {
    System.out.println("執行過濾器");
    // TODO
    filterChain.doFilter(servletRequest,servletResponse);（必寫，不寫的話有可能會報錯）
}

public void destroy() {
    System.out.println("銷燬過濾器");
}

}