Simple example of compressing HTTP request via gzip with using Spring RestTemplate

build.gradle

group 'com.github.berserkk'
version '1.0-SNAPSHOT'

apply plugin: 'java'

sourceCompatibility = 1.8

repositories {
    mavenCentral()
}

dependencies {
    compile group: 'org.springframework.boot', name: 'spring-boot-starter', version: '1.5.4.RELEASE'
    compile group: 'org.springframework', name: 'spring-web', version: '4.3.9.RELEASE'
}

gzip.php

<?php
if (!function_exists('gzdecode')) {
    function gzdecode($data) {
       return gzinflate(substr($data, 10, -8));
    }
}

echo gzdecode(file_get_contents('php://input'));

Main.java

import org.springframework.http.HttpMethod;
import org.springframework.http.client.ClientHttpRequest;
import org.springframework.http.client.SimpleClientHttpRequestFactory;
import org.springframework.web.client.HttpMessageConverterExtractor;
import org.springframework.web.client.RequestCallback;
import org.springframework.web.client.ResponseExtractor;
import org.springframework.web.client.RestTemplate;

import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.util.zip.GZIPOutputStream;

public class Main {

    public static void main(String args[]) {
        RequestCallback requestCallback = new RequestCallback() {
            @Override
            public void doWithRequest(ClientHttpRequest request) throws IOException {
                GZIPOutputStream gzipOutputStream;
                try {
                    gzipOutputStream = new GZIPOutputStream(request.getBody());
                } catch (IOException ignored) {
                    return;
                }

                request.getHeaders().add("Content-Type", "application/octet-stream");
                request.getHeaders().add("Content-Encoding", "gzip");

                try {
                    String data = "Test data.";
                    gzipOutputStream.write(data.getBytes(StandardCharsets.UTF_8));
                    gzipOutputStream.flush(); // Optional in this example.
                    gzipOutputStream.finish();
                } catch (IOException ignored) {
                }
            }
        };

        RestTemplate restTemplate = new RestTemplate();
        SimpleClientHttpRequestFactory requestFactory = new SimpleClientHttpRequestFactory();
        requestFactory.setBufferRequestBody(false);
        restTemplate.setRequestFactory(requestFactory);

        ResponseExtractor<String> responseExtractor = new HttpMessageConverterExtractor<>(String.class,
                restTemplate.getMessageConverters());
        String response = restTemplate.execute("http://localhost:8080/gzip.php", HttpMethod.POST, requestCallback,
                responseExtractor);

        System.out.println(response);
    }
}