we're in the process of migrating a web app from Weblogic 5.1 to JBoss 3.2.3/Tomcat 4.1.29 and we've come across an issue caused by a change in the JSPWriter between the JSP 1.1 and JSP 1.2 specifications. We need to support both app servers.
Here's the issue: on Weblogic 5.1, the JSPWriter will implicitly convert nulls to "", whereas in Tomcat the nulls are not getting converted and we see "null" in our textfields.
This is as expected in Tomcat 4, since according to the JSP 1.2 spec:
public abstract void print(java.lang.String s) throws java.io.IOException Print a string. If the argument is null then the string "null" is printed. Otherwise, the string's characters are converted into bytes according to the platform's default character encoding, and these bytes are written in exactly the manner of the Writer.write(int) method.