Codepage support for J2SE 1.3 is broken (as documented in HPSF HOW-TO). However, IMO it doesn't have to be. For example, the encoding "cp1252" will raise a java.io.UnsupportedEncodingException on J2SE 1.3 but "Cp1252" (with a capitalized C) will not. I've successfully tested this patch on the following Sun VMs: 1.3.1_08-b03, 1.4.2_06-b03, 1.5.0_03-b07, 1.6.0-ea-b34.
Created attachment 15586 [details] Patch (unified diff) VariantSupport.java 1.15
Doing something for J2SE 1.3 isn't worth the effort especially if the risk remains that applications under younger JREs break.