用来POST方法汉字解码的过滤器

过滤器中Filter：

package filter;

import java.io.IOException;
import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

/**
 * 用于POST方法汉字解码的过滤器
 * 使用后所有的POST提交的Servlet都无需解码
 * @author miao
 *
 */
public class SetEncodingFilter implements Filter {

	String code = null;
	
	public void init(FilterConfig config) throws ServletException {
		//从init-param中得到所需的编码
		code = config.getInitParameter("code");
		if (code == null) {
			//默认设置成utf-8
			code = "utf-8";
		}
	}

	public void doFilter(ServletRequest req, ServletResponse resp, FilterChain filterChain)
		throws IOException, ServletException {
		HttpServletRequest request = (HttpServletRequest) req;
		request.setCharacterEncoding(code);
		filterChain.doFilter(req, resp);
	}

	public void destroy() {
		code = null;
	}

}

在web.xml中的配置：

<filter>
  	<display-name>汉字的解码器</display-name>
  	<filter-name>SetEncodingFilter</filter-name>
  	<filter-class>filter.SetEncodingFilter</filter-class>
  	<init-param>
  		<param-name>code</param-name>
  		<param-value>GBK</param-value>
  	</init-param>
  </filter>
  <filter-mapping>
  	<filter-name>SetEncodingFilter</filter-name>
  	<url-pattern>/*</url-pattern>
  </filter-mapping>