问题
When I tried to add <a4j:support> tag to JSF 2.0, I got the following error
Tag Library supports namespace: https://ajax4jsf.dev.java.net/ajax, but no tag was defined for name: support
How is this caused and how can I solve it?
回答1:
The namespace URI https://ajax4jsf.dev.java.net/ajax is recognizable as the one from Ajax4jsf 1.x which existed in the prehistory, long before Ajax4jsf was acquired by RichFaces 3.x at 2006. Ajax4jsf 1.x is an ancient tag library which was targeted at JSF 1.1 on JSP, long before JSF 2.0 was introduced with builtin ajax functionality.
Even more, currently with JSF 2.0, JSP is deprecated and succeeded by Facelets (which a lot of starters overgeneralize as "XHTML"). JSP targeted tag libraries like Ajax4jsf 1.x are not compatible with Facelets. You basically need a JSF 2.0 compatible tag library instead. If you're looking for Ajax4jsf functionality, then you should be looking for RichFaces 4.x. Note that <a4j:support> has since RichFaces 4.x been renamed to <a4j:ajax> to be in line with JSF 2.0 standard <f:ajax>.
However, as said, JSF 2.0 thus already offers builtin ajax functionality in flavor of <f:ajax>. Given that you're attempting to use Ajax4jsf 1.x on JSF 2.0, you were perhaps reading a hopelessly outdated JSF book/tutorial/resource. I strongly recommend to put that aside and look for a more recent one, preferably not older than 2010 if you want a JSF 2.0 targeted one. You can find several sane tutorials linked somewhere in the bottom of our JSF wiki page.
Good luck.
来源：https://stackoverflow.com/questions/16016501/tag-library-supports-namespace-https-ajax4jsf-dev-java-net-ajax-but-no-tag-w