过滤器代码求解释

Question

麻烦大大们帮我解释下着个过滤器代码，FilterConfig 是什么？ 还有encoding怎么获得的？重点是 init（）方法
public class EncodingFilter implements Filter {    private FilterConfig filterConfig = null;
    private String encoding = null;     public void destroy() {
         filterConfig = null;
         encoding = null;
     }     public void doFilter(ServletRequest request, ServletResponse response,
             FilterChain filterChain) throws IOException, ServletException {
        if (request.getCharacterEncoding() == null) {
            if (encoding != null) {
                 request.setCharacterEncoding(encoding);
             }
             filterChain.doFilter(request, response);
         }
     }
     
     public void init(FilterConfig filterConfig) throws ServletException {
        this.filterConfig = filterConfig;
        this.encoding = filterConfig.getInitParameter("encoding");
     }
}

Answer 1

在web.xml里面配置
给你看看 Spring的例子
<!-- Character Encoding filter -->
<filter>
<filter-name>encodingFilter</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</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>param-name 的值就是你代码里面的get set属性
param-value 就是你要设置的值

Answer 2

看了下 web.xml 果然跟你讲的一样 谢谢了

Answer 3

确实不熟，老师讲的时候都是直接在 doFilter()方法里面直接设置编码，所以这个不懂  呵呵