If a class implements the Closeable
interface Groovy adds the withCloseable
method to the class. The withCloseable
method has a closure as argument. The code in the closure is executed and then the implementation of the close
method of the Closeable
interface is invoked. The Closeable
object is passed as argument to the closure, so we can refer to it inside the closure.
In the following example we have two objects that implement the Closeable
interface. By using withCloseable
we know for sure the close
method is invoked after all the code in the closure is executed:
@Grab(group='org.apache.httpcomponents', module='httpclient', version='4.5.3') import org.apache.http.impl.client.HttpClientBuilder import org.apache.http.client.methods.HttpGet // HttpClientBuilder.create().build() returns a CloseableHttpClient // that implements the Closeable interface. Therefore we can use // the withCloseable method to make sure the client is closed // after the closure code is executed. HttpClientBuilder.create().build().withCloseable { client -> final request = new HttpGet('http://www.mrhaki.com') // The execute method returns a CloseableHttpResponse object // that implements the Closeable interface. We can use // withCloseable method to make sure the response is closed // after the closure code is executed. client.execute(request).withCloseable { response -> assert response.statusLine.statusCode == 200 } }
Written with Groovy 2.4.12.