Java Reference
In-Depth Information
Figure 3.2. Using the JSR 223
ScriptEngine
to invoke a Groovy script. Java creates a
ScriptEngineManager
, which then yields a
ScriptEngine
. After supplying parameters to the engine, its
eval
method is invoked to execute a Groovy script.
The next listing demonstrates the API in action in a simple “Hello, World!” Groovy script.
Listing 3.2. Using the
ScriptEngine
to execute a simple Groovy script
I retrieve the Groovy script engine by calling the
getEngineByName
method. I then
use two different overloads of the
eval
method: one that takes a
String
argument and
one that takes an implementation of the
java.io.Reader
interface. In the first case,
the supplied string needs to be the actual scripting code. For the reader, though, I use a
FileReader
wrapped around the “Hello, Groovy!” script. The output is what you would
expect in each case.
Supplying Parameters to a Groovy Script
What if the Groovy script took input parameters and returned data? In the Groovy scripting
world this is handled through a
binding
. When I discuss the
GroovyShell
in the next
