| Tag Attributes |
| Hello Tag |
| Mail Tag |
Tags become more useful once you add attributes. This example creates a tag.
With session rewriting, even browsers without cookies can support sessions. However, every needs a call to , which is annoying. With the tag, you get that for free.
| Using an attribute taglib |
<%@ taglib prefix="ct" uri="WEB-INF/tags.tld" %> Message: <ct:href href="test.jsp">test link</ct:href> |
Message: <a href="test.jsp;jsessionid=1234">test link</a> |
| Defining the tag |
The href tag has a single attribute . Corresponding to the attribute , the HrefTag class implements and methods.
package test;
import java.io.*;
import javax.servlet.jsp.*;
import javax.servlet.jsp.tagext.*;
public class HrefTag extends TagSupport {
private String href;
public String getHref()
{
return href;
}
public void setHref(String href)
{
this.href = href;
}
public int doStartTag() throws JspException
{
try {
JspWriter out = pageContext.getOut();
HttpServletResponse response;
response = (HttpServletResponse) pageContext.getResponse();
out.print("<a href=\"");
out.print(response.encodeURL(href));
out.print("\">");
} catch (IOException e) {
}
return EVAL_BODY;
}
public int doEndTag() throws JspException
{
try {
pageContext.getOut().print("</a>");
} catch (IOException e) {
}
return EVAL_PAGE;
}
}
|
| Attribute Configuration |
Each expected attribute needs an entry in the .tld. In this case, is a required attribute, so the configuration needs to set . By setting , the JSP parser can detect errors at parse-time, making it easier to develop JSP pages with the tag library.
<taglib>
<tag>
<name>href</name>
<tagclass>test.HrefTag</tagclass>
<attribute>
<name>href</name>
<required>true</required>
</attribute>
</tag>
</taglib>
|
| Hello Tag |
| Mail Tag |
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