Filter

package cong;

import java.io.IOException;
import java.util.regex.Pattern;

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;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

/**
 * @author E-mail:congpeixue@126.com
 * @version 创建时间：2008-6-18 下午09:09:30 类说明
 */
public class PaginationFilter implements Filter {
	private static Pattern pattern = Pattern.compile("\\d+");

	private static final Log log = LogFactory.getLog(PaginationFilter.class);

	@Override
	public void destroy() {
		// TODO Auto-generated method stub

	}

	@Override
	public void doFilter(ServletRequest request, ServletResponse response,
			FilterChain chain) throws IOException, ServletException {

		HttpServletRequest httpRequest = (HttpServletRequest) request;

		HttpServletResponse httpResponse = (HttpServletResponse) response;
		int offset = this.convertToInt(httpRequest, "pager.offset");
		int pagesize = (this.convertToInt(httpRequest, "pagesize") <= 0) ? 3
				: (this.convertToInt(httpRequest, "pagesize"));

		SystemContext.setParameter(offset, pagesize);

		chain.doFilter(httpRequest, httpResponse);
	}

	private int convertToInt(HttpServletRequest request, String name) {
		String temp = getParameter4Request(request, name);
		if (isInt(temp)) {
			return (Integer.parseInt(temp));
		}
		return 0;
	}

	private String getParameter4Request(HttpServletRequest request, String name) {
		String temp = request.getParameter(name);
		return temp;
	}

	private boolean isInt(String value) {
		if (value != null && pattern.matcher(value).matches()) {
			return true;
		}
		log.debug("PaginationFilter-->isInt:" + value + "is NULL!");
		return false;
	}

	@Override
	public void init(FilterConfig arg0) throws ServletException {
		// TODO Auto-generated method stub
	}

}