Hi all,
I'm going to writing some directives to extend Velocity. now I'm in lacking
of documents.
I've read the PPT 《Hacking Velocity》by Will Glass-Husain, and some souce
code of system directive such as "literal", "execute", but I don't
understand "foreach" till now.
I've written the following code(Mydd.java) and it can work as coded now:
-------------------file begin ------------------------------
import java.io.IOException;
import java.io.Writer;
import java.util.Iterator;
import org.apache.velocity.context.InternalContextAdapter;
import org.apache.velocity.exception.MethodInvocationException;
import org.apache.velocity.exception.ParseErrorException;
import org.apache.velocity.exception.ResourceNotFoundException;
import org.apache.velocity.runtime.directive.Directive;
import org.apache.velocity.runtime.RuntimeServices;
import org.apache.velocity.runtime.parser.node.Node;
import org.apache.velocity.exception.TemplateInitException;
import org.apache.log4j.Logger;
public class Mydd extends Directive {
private static Logger logger = Logger.getLogger(Mydd.class);
public void init(RuntimeServices rs, InternalContextAdapter context,
Node node)
throws TemplateInitException
{
super.init(rs, context, node);
}
@Override
public String getName() {
return "mydd";
}
@Override
public int getType() {
return LINE;
}
public boolean render(InternalContextAdapter context,
Writer writer, Node node) throws IOException
{
for (int i = 0; i < node.jjtGetNumChildren(); i ++) {
logger.debug("debug mydd parameter: " + node.jjtGetChild(i).
toString() + " (" + node.jjtGetChild(i).literal() + ")");
}
writer.write("Hello, world!");
return true;
}
}
-------------------file end ----------------------------------
What I want to know is:
1, the above directive's syntax in template is
#mydd(arg1 arg2 arg3 ...)
but system directives like "foreach" and "set" have COOL syntax like
"#foreach ($a in $set)", how to let my directive support syntax like this?
2, does the directive mechanism provided Velocity has other convenience or
power that I don't know ? what I know about is all in the above code :-)
Thanks in advance, any hint will be appreciated!
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