Groovy built-in REST/HTTP client?

Question

I heard that Groovy has a built-in REST/HTTP client. The only library I can find is HttpBuilder, is this it?

Basically I'm looking for a way to do HTTP GETs from inside Groovy code without having to import any libraries (if at all possible). But since this module doesn't appear to be a part of core Groovy I'm not sure if I have the right lib here.

Answer 1

You can take advantage of Groovy features like with(), improvements to URLConnection, and simplified getters/setters:

GET:

String getResult = new URL('http://mytestsite/bloop').text

POST:

String postResult
((HttpURLConnection)new URL('http://mytestsite/bloop').openConnection()).with({
    requestMethod = 'POST'
    doOutput = true
    setRequestProperty('Content-Type', '...') // Set your content type.
    outputStream.withPrintWriter({printWriter ->
        printWriter.write('...') // Your post data. Could also use withWriter() if you don't want to write a String.
    })
    // Can check 'responseCode' here if you like.
    postResult = inputStream.text // Using 'inputStream.text' because 'content' will throw an exception when empty.
})

Note, the POST will start when you try to read a value from the HttpURLConnection, such as responseCode, inputStream.text, or getHeaderField('...').

Answer 2

Native Groovy GET and POST

// GET
def get = new URL("https://httpbin.org/get").openConnection();
def getRC = get.getResponseCode();
println(getRC);
if(getRC.equals(200)) {
    println(get.getInputStream().getText());
}

// POST
def post = new URL("https://httpbin.org/post").openConnection();
def message = '{"message":"this is a message"}'
post.setRequestMethod("POST")
post.setDoOutput(true)
post.setRequestProperty("Content-Type", "application/json")
post.getOutputStream().write(message.getBytes("UTF-8"));
def postRC = post.getResponseCode();
println(postRC);
if(postRC.equals(200)) {
    println(post.getInputStream().getText());
}

Answer 3

The simplest one got to be:

def html = "http://google.com".toURL().text

Answer 4

If your needs are simple and you want to avoid adding additional dependencies you may be able to use the getText() methods that Groovy adds to the java.net.URL class:

new URL("http://stackoverflow.com").getText()

// or

new URL("http://stackoverflow.com")
        .getText(connectTimeout: 5000, 
                readTimeout: 10000, 
                useCaches: true, 
                allowUserInteraction: false, 
                requestProperties: ['Connection': 'close'])

If you are expecting binary data back there is also similar functionality provided by the newInputStream() methods.

Answer 5

HTTPBuilder is it. Very easy to use.

import groovyx.net.http.HTTPBuilder

def http = new HTTPBuilder('https://google.com')
def html = http.get(path : '/search', query : [q:'waffles'])

It is especially useful if you need error handling and generally more functionality than just fetching content with GET.

Answer 6

I don't think http-builder is a Groovy module, but rather an external API on top of apache http-client so you do need to import classes and download a bunch of APIs. You are better using Gradle or @Grab to download the jar and dependencies:

@Grab(group='org.codehaus.groovy.modules.http-builder', module='http-builder', version='0.7.1' )
import groovyx.net.http.*
import static groovyx.net.http.ContentType.*
import static groovyx.net.http.Method.*

Note: since the CodeHaus site went down, you can find the JAR at (https://mvnrepository.com/artifact/org.codehaus.groovy.modules.http-builder/http-builder)