validatetag.java

JavaWeb高级特性书中源代码

package org.it315;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.tagext.TagSupport;
public class ValidateTag extends TagSupport
{
	private String url;

	public void setUrl(String url)
	{
		this.url = url;
	}

	public int doEndTag() throws JspException
	{
		HttpServletRequest req = (HttpServletRequest)pageContext.getRequest();
		String referrer = req.getHeader("referer");
		String sitePart = "http://" + req.getServerName();
		if(referrer!=null && referrer.startsWith(sitePart))
		{
			return EVAL_PAGE;
		}
		else
		{
			try 
			{
				pageContext.forward(url);
			} 
			catch (Exception e) 
			{
				e.printStackTrace();
			}
			return SKIP_PAGE;
		}
	}
}