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Baeldung Pro comes with both absolutely No-Ads as well as finally with Dark Mode, for a clean learning experience:

>> Explore a clean Baeldung

Once the early-adopter seats are all used, the price will go up and stay at $33/year.

Partner – Microsoft – NPI EA (cat = Baeldung)
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Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.

Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.

To learn more about Java features on Azure Container Apps, visit the documentation page.

You can also ask questions and leave feedback on the Azure Container Apps GitHub page.

Partner – Microsoft – NPI EA (cat= Spring Boot)
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Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.

Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.

To learn more about Java features on Azure Container Apps, you can get started over on the documentation page.

And, you can also ask questions and leave feedback on the Azure Container Apps GitHub page.

Partner – Orkes – NPI EA (cat=Spring)
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Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.

Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.

With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.

Try a 14-Day Free Trial of Orkes Conductor today.

Partner – Orkes – NPI EA (tag=Microservices)
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Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.

Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.

With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.

Try a 14-Day Free Trial of Orkes Conductor today.

eBook – Guide Spring Cloud – NPI EA (cat=Spring Cloud)
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eBook – Mockito – NPI EA (tag = Mockito)
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Mocking is an essential part of unit testing, and the Mockito library makes it easy to write clean and intuitive unit tests for your Java code.

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eBook – Java Concurrency – NPI EA (cat=Java Concurrency)
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Handling concurrency in an application can be a tricky process with many potential pitfalls. A solid grasp of the fundamentals will go a long way to help minimize these issues.

Get started with understanding multi-threaded applications with our Java Concurrency guide:

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eBook – Reactive – NPI EA (cat=Reactive)
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Spring 5 added support for reactive programming with the Spring WebFlux module, which has been improved upon ever since. Get started with the Reactor project basics and reactive programming in Spring Boot:

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eBook – Java Streams – NPI EA (cat=Java Streams)
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Since its introduction in Java 8, the Stream API has become a staple of Java development. The basic operations like iterating, filtering, mapping sequences of elements are deceptively simple to use.

But these can also be overused and fall into some common pitfalls.

To get a better understanding on how Streams work and how to combine them with other language features, check out our guide to Java Streams:

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eBook – Jackson – NPI EA (cat=Jackson)
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Do JSON right with Jackson

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eBook – HTTP Client – NPI EA (cat=Http Client-Side)
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Get the most out of the Apache HTTP Client

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Building a REST API with Spring?

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Course – LS – NPI EA (cat=Jackson)
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Get started with Spring and Spring Boot, through the Learn Spring course:

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Course – RWSB – NPI EA (cat=REST)
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Explore Spring Boot 3 and Spring 6 in-depth through building a full REST API with the framework:

>> The New “REST With Spring Boot”

Course – LSS – NPI EA (cat=Spring Security)
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Yes, Spring Security can be complex, from the more advanced functionality within the Core to the deep OAuth support in the framework.

I built the security material as two full courses - Core and OAuth, to get practical with these more complex scenarios. We explore when and how to use each feature and code through it on the backing project.

You can explore the course here:

>> Learn Spring Security

Course – All Access – NPI EA (cat= Spring)
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All Access is finally out, with all of my Spring courses. Learn JUnit is out as well, and Learn Maven is coming fast. And, of course, quite a bit more affordable. Finally.

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Course – LSD – NPI EA (tag=Spring Data JPA)
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Spring Data JPA is a great way to handle the complexity of JPA with the powerful simplicity of Spring Boot.

Get started with Spring Data JPA through the guided reference course:

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Partner – LambdaTest – NPI EA (cat=Testing)
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End-to-end testing is a very useful method to make sure that your application works as intended. This highlights issues in the overall functionality of the software, that the unit and integration test stages may miss.

Playwright is an easy-to-use, but powerful tool that automates end-to-end testing, and supports all modern browsers and platforms.

When coupled with LambdaTest (an AI-powered cloud-based test execution platform) it can be further scaled to run the Playwright scripts in parallel across 3000+ browser and device combinations:

>> Automated End-to-End Testing With Playwright

Course – Spring Sale 2025 – NPI EA (cat= Baeldung)
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Yes, we're now running our Spring Sale. All Courses are 25% off until 26th May, 2025:

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eBook – HTTP Client – NPI (cat=HTTP Client-Side)
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The Apache HTTP Client is a very robust library, suitable for both simple and advanced use cases when testing HTTP endpoints. Check out our guide covering basic request and response handling, as well as security, cookies, timeouts, and more:

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1. Overview

In this tutorial, we’re going to illustrate the broad range of operations where the Spring REST Client — RestTemplate — can be used, and used well.

For the API side of all examples, we’ll be running the RESTful service from here.

2. Use GET to Retrieve Resources

2.1. Get Plain JSON

Let’s start simple and talk about GET requests, with a quick example using the getForEntity() API:

RestTemplate restTemplate = new RestTemplate();
String fooResourceUrl
  = "http://localhost:8080/spring-rest/foos";
ResponseEntity<String> response
  = restTemplate.getForEntity(fooResourceUrl + "/1", String.class);
Assertions.assertEquals(response.getStatusCode(), HttpStatus.OK);

Notice that we have full access to the HTTP response, so we can do things like check the status code to make sure the operation was successful or work with the actual body of the response:

ObjectMapper mapper = new ObjectMapper();
JsonNode root = mapper.readTree(response.getBody());
JsonNode name = root.path("name");
Assertions.assertNotNull(name.asText());

We’re working with the response body as a standard String here and using Jackson (and the JSON node structure that Jackson provides) to verify some details.

2.2. Retrieving POJO Instead of JSON

We can also map the response directly to a Resource DTO:

public class Foo implements Serializable {
    private long id;

    private String name;
    // standard getters and setters
}

Now we can simply use the getForObject API in the template:

Foo foo = restTemplate
  .getForObject(fooResourceUrl + "/1", Foo.class);
Assertions.assertNotNull(foo.getName());
Assertions.assertEquals(foo.getId(), 1L);

3. Use HEAD to Retrieve Headers

Let’s now have a quick look at using HEAD before moving on to the more common methods.

We’re going to be using the headForHeaders() API here:

HttpHeaders httpHeaders = restTemplate.headForHeaders(fooResourceUrl);
Assertions.assertTrue(httpHeaders.getContentType().includes(MediaType.APPLICATION_JSON));

4. Use POST to Create a Resource

In order to create a new Resource in the API, we can make good use of the postForLocation(), postForObject() or postForEntity() APIs.

The first returns the URI of the newly created Resource, while the second returns the Resource itself.

4.1. The postForObject() API

RestTemplate restTemplate = new RestTemplate();

HttpEntity<Foo> request = new HttpEntity<>(new Foo("bar"));
Foo foo = restTemplate.postForObject(fooResourceUrl, request, Foo.class);
Assertions.assertNotNull(foo);
Assertions.assertEquals(foo.getName(), "bar");

4.2. The postForLocation() API

Similarly, let’s have a look at the operation that instead of returning the full Resource, just returns the Location of that newly created Resource:

HttpEntity<Foo> request = new HttpEntity<>(new Foo("bar"));
URI location = restTemplate
  .postForLocation(fooResourceUrl, request);
Assertions.assertNotNull(location);

4.3. The exchange() API

Let’s have a look at how to do a POST with the more generic exchange API:

RestTemplate restTemplate = new RestTemplate();
HttpEntity<Foo> request = new HttpEntity<>(new Foo("bar"));
ResponseEntity<Foo> response = restTemplate
  .exchange(fooResourceUrl, HttpMethod.POST, request, Foo.class);
 
Assertions.assertEquals(response.getStatusCode(), HttpStatus.CREATED);
 
Foo foo = response.getBody();
 
Assertions.assertNotNull(foo);
Assertions.assertEquals(foo.getName(), "bar");

4.4. Submit Form Data

Next, let’s look at how to submit a form using the POST method.

First, we need to set the Content-Type header to application/x-www-form-urlencoded.

This makes sure that a large query string can be sent to the server, containing name/value pairs separated by &:

HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_FORM_URLENCODED);

We can wrap the form variables into a LinkedMultiValueMap:

MultiValueMap<String, String> map= new LinkedMultiValueMap<>();
map.add("id", "1");

Next, we build the Request using an HttpEntity instance:

HttpEntity<MultiValueMap<String, String>> request = new HttpEntity<>(map, headers);

Finally, we can connect to the REST service by calling restTemplate.postForEntity() on the Endpoint: /foos/form

ResponseEntity<String> response = restTemplate.postForEntity(
  fooResourceUrl + "/form", request , String.class);
Assertions.assertEquals(response.getStatusCode(), HttpStatus.CREATED);

5. Use OPTIONS to Get Allowed Operations

Next, we’re going to have a quick look at using an OPTIONS request and exploring the allowed operations on a specific URI using this kind of request; the API is optionsForAllow:

Set<HttpMethod> optionsForAllow = restTemplate.optionsForAllow(fooResourceUrl);
HttpMethod[] supportedMethods
  = {HttpMethod.GET, HttpMethod.POST, HttpMethod.PUT, HttpMethod.DELETE};
Assertions.assertTrue(optionsForAllow.containsAll(Arrays.asList(supportedMethods)));

6. Use PUT to Update a Resource

Next, we’ll start looking at PUT and more specifically the exchange() API for this operation, since the template.put API is pretty straightforward.

6.1. Simple PUT With exchange()

We’ll start with a simple PUT operation against the API — and keep in mind that the operation isn’t returning a body back to the client:

Foo updatedInstance = new Foo("newName");
updatedInstance.setId(createResponse.getBody().getId());
String resourceUrl = 
  fooResourceUrl + '/' + createResponse.getBody().getId();
HttpEntity<Foo> requestUpdate = new HttpEntity<>(updatedInstance, headers);
template.exchange(resourceUrl, HttpMethod.PUT, requestUpdate, Void.class);

6.2. PUT With exchange() and a Request Callback

Next, we’re going to be using a request callback to issue a PUT.

Let’s make sure we prepare the callback, where we can set all the headers we need as well as a request body:

RequestCallback requestCallback(final Foo updatedInstance) {
    return clientHttpRequest -> {
        ObjectMapper mapper = new ObjectMapper();
        mapper.writeValue(clientHttpRequest.getBody(), updatedInstance);
        clientHttpRequest.getHeaders().add(
          HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE);
        clientHttpRequest.getHeaders().add(
          HttpHeaders.AUTHORIZATION, "Basic " + getBase64EncodedLogPass());
    };
}

Next, we create the Resource with a POST request:

ResponseEntity<Foo> response = restTemplate
  .exchange(fooResourceUrl, HttpMethod.POST, request, Foo.class);
Assertions.assertEquals(response.getStatusCode(), HttpStatus.CREATED);

And then we update the Resource:

Foo updatedInstance = new Foo("newName");
updatedInstance.setId(response.getBody().getId());
String resourceUrl = fooResourceUrl + '/' + response.getBody().getId();
restTemplate.execute(
  resourceUrl, 
  HttpMethod.PUT, 
  requestCallback(updatedInstance), 
  clientHttpResponse -> null);

7. Use DELETE to Remove a Resource

To remove an existing Resource, we’ll make quick use of the delete() API:

String entityUrl = fooResourceUrl + "/" + existingResource.getId();
restTemplate.delete(entityUrl);

8. Configure Timeout

There are four different types of timeouts we can configure:

  • Connect Timeout – the time to wait for the HTTP connection to be established. We configure this in RequestConfig
  • Read Timeout – the time the client should wait for the server to respond. We configure this in RequestConfig
  • Socket Timeout – the connection timeout for SSL handshakes or CONNECT requests. We configure this in SocketConfig
  • Connection Request Timeout – the amount of time to wait when requesting a connection from RequestConfig‘s connection manager

We can configure RestTemplate to time out by simply using ClientHttpRequestFactory:

RestTemplate restTemplate = new RestTemplate(getClientHttpRequestFactory());

ClientHttpRequestFactory getClientHttpRequestFactory() {
    int timeout = 5;
    HttpComponentsClientHttpRequestFactory clientHttpRequestFactory = new 
      HttpComponentsClientHttpRequestFactory();
    clientHttpRequestFactory.setConnectionRequestTimeout(timeout*1000);
    clientHttpRequestFactory.setConnectTimeout(timeout*2000);
    clientHttpRequestFactory.setReadTimeout(timeout*3000);
    return clientHttpRequestFactory;
}

Also, we can use HttpClient to configure all types of timeout options. A benefit of using this approach is that we can set other configuration settings as well in the ConnectionConfig, RequestConfig, and SocketConfig:

ClientHttpRequestFactory getClientHttpRequestFactoryAlternate() {
    long timeout = 5; 
    int readTimeout = 5;

    // Connect timeout
    ConnectionConfig connectionConfig = ConnectionConfig.custom()
      .setConnectTimeout(Timeout.ofMilliseconds(timeout*1000))
      .build();
    
    // Connection Request timeout    
    RequestConfig requestConfig = RequestConfig.custom()
      .setConnectionRequestTimeout(Timeout.ofMilliseconds(timeout*2000))
      .build();

    // Socket timeout
    SocketConfig socketConfig = SocketConfig.custom() 
      .setSoTimeout(Timeout.ofMilliseconds(timeout*1000)).build();

    PoolingHttpClientConnectionManager connectionManager = 
      new PoolingHttpClientConnectionManager();
    connectionManager.setDefaultSocketConfig(socketConfig);
    connectionManager.setDefaultConnectionConfig(connectionConfig);    

    CloseableHttpClient httpClient = HttpClientBuilder.create()
      .setConnectionManager(connectionManager)
      .setDefaultRequestConfig(requestConfig)
      .build();

    HttpComponentsClientHttpRequestFactory clientHttpRequestFactory = new 
      HttpComponentsClientHttpRequestFactory(httpClient);

    // Read timeout
    clientHttpRequestFactory.setReadTimeout(readTimeout*3000);
  
    return clientHttpRequestFactory;
}

9. Conclusion

In this article, we went over the main HTTP Verbs, using RestTemplate to orchestrate requests using all of these.

If you want to dig into how to do authentication with the template, check out our article on Basic Auth with RestTemplate.

The code backing this article is available on GitHub. Once you're logged in as a Baeldung Pro Member, start learning and coding on the project.
Baeldung Pro – NPI EA (cat = Baeldung)
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Baeldung Pro comes with both absolutely No-Ads as well as finally with Dark Mode, for a clean learning experience:

>> Explore a clean Baeldung

Once the early-adopter seats are all used, the price will go up and stay at $33/year.

Partner – Microsoft – NPI EA (cat = Spring Boot)
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Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.

Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.

To learn more about Java features on Azure Container Apps, visit the documentation page.

You can also ask questions and leave feedback on the Azure Container Apps GitHub page.

Partner – Orkes – NPI EA (cat = Spring)
announcement - icon

Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.

Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.

With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.

Try a 14-Day Free Trial of Orkes Conductor today.

Partner – Orkes – NPI EA (tag = Microservices)
announcement - icon

Modern software architecture is often broken. Slow delivery leads to missed opportunities, innovation is stalled due to architectural complexities, and engineering resources are exceedingly expensive.

Orkes is the leading workflow orchestration platform built to enable teams to transform the way they develop, connect, and deploy applications, microservices, AI agents, and more.

With Orkes Conductor managed through Orkes Cloud, developers can focus on building mission critical applications without worrying about infrastructure maintenance to meet goals and, simply put, taking new products live faster and reducing total cost of ownership.

Try a 14-Day Free Trial of Orkes Conductor today.

eBook – HTTP Client – NPI EA (cat=HTTP Client-Side)
announcement - icon

The Apache HTTP Client is a very robust library, suitable for both simple and advanced use cases when testing HTTP endpoints. Check out our guide covering basic request and response handling, as well as security, cookies, timeouts, and more:

>> Download the eBook

eBook – Java Concurrency – NPI EA (cat=Java Concurrency)
announcement - icon

Handling concurrency in an application can be a tricky process with many potential pitfalls. A solid grasp of the fundamentals will go a long way to help minimize these issues.

Get started with understanding multi-threaded applications with our Java Concurrency guide:

>> Download the eBook

eBook – Java Streams – NPI EA (cat=Java Streams)
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Since its introduction in Java 8, the Stream API has become a staple of Java development. The basic operations like iterating, filtering, mapping sequences of elements are deceptively simple to use.

But these can also be overused and fall into some common pitfalls.

To get a better understanding on how Streams work and how to combine them with other language features, check out our guide to Java Streams:

>> Join Pro and download the eBook

eBook – Persistence – NPI EA (cat=Persistence)
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Working on getting your persistence layer right with Spring?

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Course – LS – NPI EA (cat=REST)

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Get started with Spring Boot and with core Spring, through the Learn Spring course:

>> CHECK OUT THE COURSE

Course – Spring Sale 2025 – NPI EA (cat= Baeldung)
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Yes, we're now running our Spring Sale. All Courses are 25% off until 26th May, 2025:

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Course – Spring Sale 2025 – NPI (All)
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Yes, we're now running our Spring Sale. All Courses are 25% off until 26th May, 2025:

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Course – LS – NPI (cat=HTTP Client-Side)
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Get started with Spring Boot and with core Spring, through the Learn Spring course:

>> CHECK OUT THE COURSE

Partner – Microsoft – NPI (cat=Spring)
announcement - icon

Azure Container Apps is a fully managed serverless container service that enables you to build and deploy modern, cloud-native Java applications and microservices at scale. It offers a simplified developer experience while providing the flexibility and portability of containers.

Of course, Azure Container Apps has really solid support for our ecosystem, from a number of build options, managed Java components, native metrics, dynamic logger, and quite a bit more.

To learn more about Java features on Azure Container Apps, visit the documentation page.

You can also ask questions and leave feedback on the Azure Container Apps GitHub page.

eBook Jackson – NPI EA – 3 (cat = Jackson)