Pretty Printing Groovy's StreamingMarkupBuilder

Unfortunately, Groovy's StreamingMarkupBuilder will not output indented xml due to its streaming nature. However, never fear, JTidy is here to save the day!

JTidy is a project hosted here on sourceforge and it is a pretty nice HTML/XML pretty printer. It also seems to check your HTML for errors, which is cool! Examples are lacking however so I thought I would share my findings with this example:

public class JTidyExample {

def tidyMeUp(String singleLine) {
StringWriter writer = new StringWriter()
Tidy tidy = new Tidy()
tidy.identity {
  setEscapeCdata(false)//leave cdata untouched
  setIndentCdata(true)//indent the CData
  setXmlTags(true)//working with xml not html
  parse(new StringReader(singleLine), writer)
}
writer.toString()
}

def createMarkUp() {
String cData = "<![CDATA[hello]]>"
StreamingMarkupBuilder xml = new StreamingMarkupBuilder();
def person1 = {
  person(id: 1) {
    firstName("John")
    lastName("Doe")
    data_labels {
      mkp.yieldUnescaped(cData)
    }
  }
}
def personList = {
  people {
    out << person1
  }
}
xml.bind(personList).toString()
}

def static main(def args) {
def example = new JTidyExample()
def singleLine = example.createMarkUp()
println "Before: \n ${singleLine}"
println "After: \n ${example.tidyMeUp(singleLine)}"
}

}

The following is output:

Before:

<people><person id='1'><firstName>John</firstName><lastName>Doe</lastName><data_labels><![CDATA[hello]]></data_labels></person></people>

Tidy (vers 26-Sep-2004) Parsing "InputStream"
no warnings or errors were found

After:

<people>
<person id='1'>
<firstName>John</firstName>
<lastName>Doe</lastName>
<data_labels>
  <![CDATA[hello]]>
</data_labels>
</person>
</people>

Here we can see that our XML is now nicely indented. Want some more??? Check out Scott Davis' Groovy Recipes, it has a pretty sweet XML section!

UPDATE: Check out Paul Kings comments where he suggests using groovy.xml.XmlUtil.serialize(xml.bind(personList)). Sweet!