作为servlet而不是java类工作。 为什么？

Question

I am working on SAML SSO Authentication. I have created a servlet to generate SAML metadata and i deployed it and run it and I got the output. Same time I have created a java class to generate SAML Metadata with the same code and tried to run it independently. I have added the same Jar files that I have used for that servlet application. But I got the Exception given below. Can anybody help me to find the difference between running an application independently and by using java servlet?? Thanks in advance.

Exception:

Answer 1

Running as servlet in a web container means all sorts of stuff is on the classpath that is automatically provided by the servlet container.

Running using main() means you have to put all needed stuff on the classpath yourself. The ClassNotFoundException you got should be clear enough in that respect.

(Pls note that although I did say "the" classpath, in a servlet container things are typically not quite that simple. But that's not the point. Also note that running as a servlet, and using features of libraries provided for the container, may even mean your stuff cannot run as an independent java program simply because the library stuff was deliberately intended for servlet container use exclusively.)