Groovy Builder support
Ho开发者_如何学Cw can i build the above pattern using groovy builder support
emp = empFileFactory.root()
{
emp(id: '3', value: '1')
emp(id:'24')
{
emp(id: '1', value: '2')
emp(id: '6', value: '7')
emp(id: '7', value: '1')
}
emp(id: '25')
{
emp(id: '1', value: '1')
emp(id: '6', value: '7')
}
}
i'm trying to build the above strucutre in groovy can some one explain how could i acieve this
You can do something like this (this has no error handling, and just returns null for methods that I don't expect to be called):
// First define our class to hold our created 'Emp' objects
@groovy.transform.Canonical
class Emp {
String id
String value
List<Emp> children = []
}
class EmpBuilder extends BuilderSupport{
def children = []
protected void setParent(Object parent, Object child){
parent.children << child
}
protected Object createNode(Object name){
if( name == 'root' ) {
this
}
else {
null
}
}
protected Object createNode(Object name, Object value){
null
}
protected Object createNode(Object name, Map attributes){
if( name == 'emp' ) {
new Emp( attributes )
}
else {
null
}
}
protected Object createNode(Object name, Map attributes, Object value){
null
}
protected void nodeCompleted(Object parent, Object node) {
}
Iterator iterator() { children.iterator() }
}
Then, if we call this with your required builder code like so:
b = new EmpBuilder().root() {
emp(id: '3', value: '1')
emp(id:'24') {
emp(id: '1', value: '2')
emp(id: '6', value: '7')
emp(id: '7', value: '1')
}
emp(id: '25') {
emp(id: '1', value: '1')
emp(id: '6', value: '7')
}
}
We can print out the 'tree' like so
b.each { println it }
and see we get the structure we asked for:
Emp(3, 1, [])
Emp(24, null, [Emp(1, 2, []), Emp(6, 7, []), Emp(7, 1, [])])
Emp(25, null, [Emp(1, 1, []), Emp(6, 7, [])])
You want to implement extend the BuilderSupport
class, which is pretty easy to do. There's a pretty nice tutorial here.
You need to implement a few methods, but the naming should be pretty self-explanatory:
createNode
creates a node (each node has a name and optional attributes and/or a value)setParent
assigns a node as another nodes parent
That's pretty much it.
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