GET + body by RestTemplate

build.gradle

plugins {
	id 'java'
	id 'org.springframework.boot' version '3.2.1'
	id 'io.spring.dependency-management' version '1.1.4'
}

group = 'com.example'
version = '0.0.1-SNAPSHOT'

java {
	sourceCompatibility = '17'
}

repositories {
	mavenCentral()
}

dependencies {
	implementation 'org.springframework.boot:spring-boot-starter-web'
	implementation 'org.apache.httpcomponents.client5:httpclient5'
	implementation 'io.projectreactor.netty:reactor-netty-http'
	implementation 'org.eclipse.jetty:jetty-client'
	implementation 'com.squareup.okhttp3:okhttp'
	testImplementation 'org.springframework.boot:spring-boot-starter-test'
}

tasks.named('test') {
	useJUnitPlatform()
}

DemoApplication.java

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

@SpringBootApplication
@RestController("/")
public class DemoApplication {
	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}

	@GetMapping
	public String echo(@RequestBody String body) {
		return body;
	}

}

GetWithBodyRequestTest.java

package com.example.demo;

import static org.assertj.core.api.Assertions.assertThat;

import java.net.URI;
import java.util.stream.Stream;

import org.junit.jupiter.params.ParameterizedTest;
import org.junit.jupiter.params.provider.MethodSource;
import org.springframework.http.HttpEntity;
import org.springframework.http.HttpMethod;
import org.springframework.http.ResponseEntity;
import org.springframework.http.client.ClientHttpRequestFactory;
import org.springframework.http.client.HttpComponentsClientHttpRequestFactory;
import org.springframework.http.client.JdkClientHttpRequestFactory;
import org.springframework.http.client.JettyClientHttpRequestFactory;
import org.springframework.http.client.OkHttp3ClientHttpRequestFactory;
import org.springframework.http.client.ReactorNettyClientRequestFactory;
import org.springframework.http.client.SimpleClientHttpRequestFactory;
import org.springframework.web.client.RestTemplate;

class GetWithBodyRequestTest {

	@ParameterizedTest
	@MethodSource("provideRequestFactory")
	void requestGetWithBody(ClientHttpRequestFactory requestFactory) {
		var restTemplate = new RestTemplate(requestFactory);
		var request = new HttpEntity<>("hello1");

		ResponseEntity<String> response = restTemplate.exchange(
			URI.create("http://localhost:8080/"),
			HttpMethod.GET,
			request,
			String.class
		);

		assertThat(response.getBody()).isEqualTo("hello1");
	}

	static Stream<ClientHttpRequestFactory> provideRequestFactory() {
		return Stream.of(
			new JdkClientHttpRequestFactory(), //  success
			new HttpComponentsClientHttpRequestFactory(), // success
			new ReactorNettyClientRequestFactory(), // success
			new JettyClientHttpRequestFactory(), // success
			new SimpleClientHttpRequestFactory(), // fail
			new OkHttp3ClientHttpRequestFactory() // fail
		);
	}
}