Question

I want to define a jsp tag, which can accept some extra attributes which are not declared in the .tld file. Is it possible?

I want this because I want to define a <cms:img> tag, which will generate a html img tag. User can pass some attributes to it, but I don’t want to limit user, I hope they can use it just as a normal html img tag.

For example, user can use this tag and pass some required information:

<cms:img id="111" />

Which will generate a html img tag as:

<img src="/show_images?id=111" />

All I need is a id attribute.

But user may treat it as a normal html img tag, and pass some extra attributes to it, like:

<cms:img id="111" width="100px" height="100px" style="..." more attributes .. />

I don’t want to declare the other attributes in my tag, because there are too many, and user may have their custom attributes.

So I want to know: Can I just declare the id attribute in the jsp tag, but let it accept all the other undeclared attributes?

Answer 1

Yes, it’s possible. These are called dynamic attributes. See http://docs.oracle.com/javaee/1.4/tutorial/doc/JSPTags5.html#wp89775:

dynamic-attributes (optional)

Indicates whether this tag supports
additional attributes with dynamic names. The value identifies a
scoped attribute in which to place a Map containing the names and
values of the dynamic attributes passed during invocation of the tag.
A translation error results if the value of the dynamic-attributes of
a tag directive is equal to the value of a name-given of a variable
directive or the value of a name attribute of an attribute directive.