groovy - problem parsing xml

I am new to Groovy and I am trying to parse both a valid rest resource and an invalid one. For example:

this code works fine -

def entity = new XmlSlurper().parse('http://api.twitter.com/1/users/show/slashdot.xml')
println entity.开发者_运维百科name()
println entity.screen_name.text()

when I run it, I get output:

user
slashdot

but when I pass an invalid url to xmlSlurper, like this

def entity = new XmlSlurper().parse('http://api.twitter.com/1/users/show/slashdotabc.xml')
println entity.name()
println entity.screen_name.text(

)

I get this error message:

Caught: java.io.FileNotFoundException: http://api.twitter.com/1/users/show/slashdotabc.xml
    at xmltest.run(xmltest.groovy:1)

Although the url returns an hash code (like below) with an error message which I would like to parse and display it.

<hash>
<request>/1/users/show/slashdotabc.xml</request>
<error>Not found</error>
</hash>

How can I parse a url which returns a 404 but with error information?

Any help will be appreciated.

-- Thanks & Regards, Frank Covert

The response you want to see is available on the URL connection's errorStream instead of the inputStream. Fortunately, given the InputStream, XmlSlurper.parse can read an InputStream as well.

Here's a sample to switch to reading the errorStream when you don't get a 200 status:

def con = new URL("http://api.twitter.com/1/users/show/slashdotaxxxbc.xml").openConnection()
def xml = new XmlSlurper().parse(con.responseCode == 200 ? con.inputStream : con.errorStream)