Apache Groovy and Java class libraries
Apache Groovy is a dynamic programming language designed for the Java platform. It is closely interacting with Java to allow developers to quickly and simple expansion on the existing Java class library.This article will explore the interoperability between Apache Groovy and Java class libraries and provide some Java code examples.
1. Call the Java class library: Groovy can directly call the methods and objects in the Java class library.The following is an example code that uses Apache HttpClient library to send HTTP requests:
groovy
@Grab('org.apache.httpcomponents:httpclient:4.5.13')
import org.apache.http.client.methods.HttpGet
import org.apache.http.impl.client.CloseableHttpClient
import org.apache.http.impl.client.HttpClients
CloseableHttpClient httpClient = HttpClients.createDefault()
HttpGet httpGet = new HttpGet("https://www.example.com")
CloseableHttpResponse response = httpClient.execute(httpGet)
try {
println(response.getStatusLine().getStatusCode())
} finally {
response.close()
httpClient.close()
}
2. Use the characteristics of the Java library: Groovy can not only use the methods and objects in the Java class library, but also further enhanced through its flexible grammar and characteristics.The following is an example code using the Apache Commons Lang library to reverse the string and sort by the letter:
groovy
@Grab('org.apache.commons:commons-lang3:3.12.0')
import org.apache.commons.lang3.StringUtils
def str = "Groovy is awesome!"
def reversed = StringUtils.reverse(str)
def sorted = StringUtils.sortByCharacterType(reversed)
println(sorted)
3. Extended Java library: Groovy also allows developers to expand the Java class library to add new functions or modify existing functions to them.The following is an example code. By expanding the HashMap class of Java, add a new method of printing:
groovy
import java.util.HashMap
class CustomHashMap extends HashMap {
void print() {
each { key, value ->
println("${key} -> ${value}")
}
}
}
def map = new CustomHashMap()
map.put("name", "John")
map.put("age", 30)
map.print()
Summary: Apache Groovy provides the ability to seamlessly operate between the Java class library.Developers can easily call the methods and objects in the existing Java library, use Groovy's syntax and characteristics to enhance their functions, and expand the Java class library to meet specific needs.This interoperability makes Groovy an ideal choice for Java developers to develop and test quickly in the project.
