Enhance toString() to return structured info, for certificate and probably more

[Weijun Wang]

Hi All

I was talking with Xuelei on how to better display certificate info. 
There are 3 cases we can currently think of:

1. debug output
2. keytool/jarsigner output
3. Java plugin display

The 1st one is the most primitive one and can be a single string, the 
2nd is also a string but have some format and needs to localized, the 
third is a series of Swing controls.

But the contents of all 3 are the same, and hopefully can be provided in 
a single method. Each consumer can just display it in its own style, 
with no need to understand Certificate fields, OIDs, etc. It's just like 
XSLT transformation of XML files.

So what shall I do? Let toString() outputs a long string in XML or JSON?

Or, create a new method describe() or toDescription() that returns a 
UnmodifiableMap (based on a LinkedHashMap to preserve order)?

I prefer the latter because there is no need to parse the output, and at 
least in the case of certificate, since a certificate contains 
extensions, it's very easy to stuff several maps inside another one. The 
map's keys are strings, and values can be another map or a simple data 
object, say, primitive, string, or Date.

So this needs a new interface Descriptable. It can either be:

    interface sun.security.util.Descriptable;
    sun.security.x509.X509CertImpl implements Descriptable;
    sun.security.x509.Extension implements Descriptable;

or

    interface java.security.Descriptable;
    java.security.cert.X509Certificate implements Descriptable;
    java.security.cert.Extension implements Descriptable;

or if there are other people find it useful, it can be inside the 
java.util package.

What's your ideas? Do you also need such a method?

Thanks
Max