Spring RestTemplate Guide: GET, POST, PUT, DELETE Examples
Learn Spring RestTemplate with real-world examples for GET, POST, PUT, DELETE.
20+ years shipping production Java in banking & fintech. Written from production experience, not tutorials.
- ✓Basic knowledge of Spring Boot and dependency injection
- ✓Familiarity with REST API concepts (HTTP methods, status codes)
- ✓Java 17+ (though RestTemplate works with Java 8+)
- ✓A Spring Boot project with spring-web dependency
- RestTemplate is Spring's synchronous HTTP client for calling REST APIs.
- Used for GET, POST, PUT, DELETE operations with methods like getForObject(), postForObject(), exchange().
- Prefer WebClient for new reactive projects; RestTemplate is in maintenance mode.
- Always set connect and read timeouts to avoid thread starvation.
- Handle errors with ResponseErrorHandler; never ignore HTTP error statuses.
Think of RestTemplate as a delivery person you send to fetch data from another service. You hand them an address (URL), they go get the package (response), and bring it back. If the address is wrong or the package is missing, they tell you—but only if you've taught them how to report problems. RestTemplate is synchronous, meaning you wait until they return before doing anything else. That's fine for simple errands, but if you have many deliveries to make, you might want a faster, non-blocking approach like WebClient.
If you've built a Spring Boot application that talks to another service, you've almost certainly used RestTemplate. It's been the go-to synchronous HTTP client for years. But here's the hard truth: RestTemplate is in maintenance mode. Spring officially recommends WebClient for new projects. Yet, millions of lines of production code still rely on RestTemplate, and you'll encounter it in legacy systems, internal APIs, and third-party integrations. Understanding RestTemplate deeply isn't optional—it's essential for any Spring developer.
In this guide, I'll walk you through real-world examples of GET, POST, PUT, and DELETE operations. But more importantly, I'll share the pitfalls I've seen in production: thread starvation from missing timeouts, silent failures from inadequate error handling, and memory leaks from not closing responses. We'll also cover testing with MockRestServiceServer and migrating to WebClient when you're ready.
By the end, you'll know not just how to use RestTemplate, but how to use it safely in production. Let's get our hands dirty.
Setting Up RestTemplate: The Right Way
Most tutorials show you how to create a RestTemplate with new . That's fine for prototyping, but in production, you need to configure it properly. Here's my recommended setup:RestTemplate()
First, avoid creating a new RestTemplate instance for every request. That's wasteful and can lead to socket exhaustion. Instead, create a single, reusable bean.
Second, always use Apache HttpClient or OkHttp as the underlying implementation. The default SimpleClientHttpRequestFactory has limitations (no connection pooling, no proper timeout handling). I prefer HttpClient from Apache HttpComponents because it's battle-tested and highly configurable.
Here's a configuration class that sets up RestTemplate with sensible defaults:
```java @Configuration public class RestTemplateConfig {
@Bean public RestTemplate restTemplate() { // Use HttpClient for better control HttpClient httpClient = HttpClientBuilder.create() .setMaxConnTotal(200) .setMaxConnPerRoute(20) .setDefaultRequestConfig(RequestConfig.custom() .setConnectTimeout(5000) // 5 seconds .setSocketTimeout(5000) // 5 seconds .setConnectionRequestTimeout(5000) .build()) .build();
HttpComponentsClientHttpRequestFactory factory = new HttpComponentsClientHttpRequestFactory(httpClient); RestTemplate restTemplate = new RestTemplate(factory);
// Custom error handler to log response body restTemplate.setErrorHandler(new DefaultResponseErrorHandler() { @Override public void handleError(ClientHttpResponse response) throws IOException { String body = new String(response.getBody().readAllBytes(), StandardCharsets.UTF_8); log.error("HTTP {} {}: {}", response.getStatusCode(), response.getStatusText(), body); throw new HttpClientErrorException(response.getStatusCode(), response.getStatusText(), body.getBytes(), null); } });
return restTemplate; } } ```
Notice I set timeouts on the RequestConfig, not on the factory directly. This gives you finer control. Also, I override the error handler to capture the response body. The default error handler throws an exception but loses the body, making debugging a nightmare.
One more thing: if you're using Spring Boot 3.x, RestTemplate is still available but you need to add the spring-web dependency explicitly. It's no longer auto-configured. Spring Boot 3.2+ even deprecates some RestTemplate methods. Consider this your wake-up call to evaluate WebClient.
GET Requests: Fetching Resources
GET requests are the most common. RestTemplate offers several methods: getForObject(), getForEntity(), and exchange(). I'll show you each and when to use them.
getForObject() is the simplest. It deserializes the response body directly into your target type. Use this when you only need the body and don't care about headers or status code.
``java public Payment getPayment(String id) { String url = "https://api.payments.com/v1/payments/{id}"; return restTemplate.getForObject(url, Payment.class, id); } ``
getForEntity() returns a ResponseEntity that includes headers, status code, and body. Use this when you need to inspect the response status or headers.
``java public ResponseEntity<Payment> getPaymentWithHeaders(String id) { String url = "https://api.payments.com/v1/payments/{id}"; return restTemplate.getForEntity(url, Payment.class, id); } ``
exchange() is the most flexible. It allows you to set the HTTP method, request entity (including headers and body), and response type. Use this when you need to add custom headers (like authentication tokens) or when you're calling a non-standard API.
``java public Payment getPaymentWithAuth(String id, String token) { String url = "https://api.payments.com/v1/payments/{id}"; HttpHeaders headers = new ``HttpHeaders(); headers.setBearerAuth(token); HttpEntity<Void> entity = new HttpEntity<>(headers); ResponseEntity<Payment> response = restTemplate.exchange(url, HttpMethod.GET, entity, Payment.class, id); return response.getBody(); }
Production tip: Always use URI variables instead of string concatenation. It's safer (URL encoding) and cleaner. Also, be aware that getForObject() throws RestClientException for non-2xx responses. If you need to handle errors gracefully, use exchange() with a custom error handler or catch the exception.
What about query parameters? Use UriComponentsBuilder to build URLs with query parameters. Don't concatenate strings—you'll miss encoding and introduce bugs.
``java UriComponentsBuilder builder = UriComponentsBuilder.fromHttpUrl(url) .queryParam("status", "APPROVED") .queryParam("limit", 10); String finalUrl = builder.toUriString(); ``
exchange() and check the status code.exchange() for full control.POST Requests: Creating Resources
POST requests create new resources. RestTemplate provides postForObject(), postForEntity(), and postForLocation(). Let's break them down.
postForObject() sends a POST request and deserializes the response body. Use this when the API returns the created resource.
``java public Payment createPayment(PaymentRequest request) { String url = "https://api.payments.com/v1/payments"; return restTemplate.postForObject(url, request, Payment.class); } ``
postForEntity() returns a ResponseEntity, giving you access to headers and status. This is useful when you need to check the Location header or the exact status code.
``java public ResponseEntity<Payment> createPaymentWithResponse(PaymentRequest request) { String url = "https://api.payments.com/v1/payments"; return restTemplate.postForEntity(url, request, Payment.class); } ``
postForLocation() returns the URI of the newly created resource (from the Location header). This is common in RESTful APIs that follow the 201 Created pattern.
``java public URI createPaymentAndGetLocation(PaymentRequest request) { String url = "https://api.payments.com/v1/payments"; return restTemplate.postForLocation(url, request); } ``
Production tip: Always set Content-Type header explicitly if you're sending JSON. RestTemplate usually does this automatically if you pass an object (it uses Jackson), but if you're sending a String, it may default to text/plain. Use HttpEntity to set headers explicitly.
``java HttpHeaders headers = new ``HttpHeaders(); headers.setContentType(MediaType.APPLICATION_JSON); HttpEntity<PaymentRequest> entity = new HttpEntity<>(request, headers); ResponseEntity<Payment> response = restTemplate.exchange(url, HttpMethod.POST, entity, Payment.class);
What about large payloads? If you're sending large JSON, consider using StreamingOutput to avoid loading the entire payload into memory. But that's an advanced topic—for most cases, RestTemplate handles it fine.
Error handling: POST requests often return 400 Bad Request for validation errors. Your custom error handler should log the response body to help debug client-side issues. Also, be prepared for 409 Conflict if the resource already exists.
PUT and PATCH Requests: Updating Resources
PUT replaces a resource entirely; PATCH applies partial updates. RestTemplate supports both via exchange() or put()/patchForObject() (patchForObject is available in Spring 5+).
PUT with put() is straightforward but doesn't return a response body. Use this when you don't care about the response (or the API returns 204 No Content).
``java public void updatePayment(String id, PaymentUpdate update) { String url = "https://api.payments.com/v1/payments/{id}"; restTemplate.put(url, update, id); } ``
PUT with exchange() when you need the response body or want to set headers.
``java public Payment updatePaymentWithResponse(String id, PaymentUpdate update) { String url = "https://api.payments.com/v1/payments/{id}"; HttpHeaders headers = new ``HttpHeaders(); headers.setContentType(MediaType.APPLICATION_JSON); HttpEntity<PaymentUpdate> entity = new HttpEntity<>(update, headers); ResponseEntity<Payment> response = restTemplate.exchange(url, HttpMethod.PUT, entity, Payment.class, id); return response.getBody(); }
PATCH is less common but equally important. Spring 5 introduced patchForObject() and exchange() with HttpMethod.PATCH.
``java public Payment patchPayment(String id, Map<String, Object> fields) { String url = "https://api.payments.com/v1/payments/{id}"; HttpHeaders headers = new ``HttpHeaders(); headers.setContentType(MediaType.APPLICATION_JSON); HttpEntity<Map<String, Object>> entity = new HttpEntity<>(fields, headers); ResponseEntity<Payment> response = restTemplate.exchange(url, HttpMethod.PATCH, entity, Payment.class, id); return response.getBody(); }
Production tip: PATCH is often implemented as a JSON merge patch (RFC 7396) or JSON Patch (RFC 6902). Know which one your API uses. The example above sends a map of fields to update, which works for merge patch. For JSON Patch, you'd send a list of operations.
Idempotency: PUT is idempotent; PATCH is not necessarily. If you're retrying requests, be careful with PATCH. Also, some APIs require an If-Match header with an ETag for optimistic locking. Use exchange() to set that header.
Common mistake: Forgetting to set Content-Type when sending a PATCH request. Some servers are picky and will reject the request if it's not application/json-patch+json for JSON Patch.
put() for simple updates without response, exchange() for full control. For PATCH, know the patch format (merge vs JSON Patch) and set Content-Type accordingly.DELETE Requests: Removing Resources
DELETE is straightforward but often mishandled. RestTemplate provides delete() and exchange() with HttpMethod.DELETE.
delete() is simple—it sends a DELETE request and doesn't return a response body. Use this when you don't need to inspect the response.
``java public void deletePayment(String id) { String url = "https://api.payments.com/v1/payments/{id}"; restTemplate.delete(url, id); } ``
exchange() with DELETE when you need to check the response status or headers.
``java public boolean deletePaymentWithCheck(String id) { String url = "https://api.payments.com/v1/payments/{id}"; ResponseEntity<Void> response = restTemplate.exchange(url, HttpMethod.DELETE, null, Void.class, id); return response.getStatusCode().is2xxSuccessful(); } ``
Production tip: DELETE responses typically return 204 No Content or 200 OK. If the API returns a body (e.g., the deleted resource), use exchange() with a response type. Also, some APIs require a reason header for audit purposes—use exchange() to set it.
Idempotency: DELETE is idempotent. Calling it multiple times should return the same result (404 after the first deletion is acceptable). But be careful: some APIs return 404 for non-existent resources, which your error handler might treat as an error. Decide whether 404 is an error or a success in your context.
Common mistake: Not handling 404 gracefully. If you call delete() on a resource that doesn't exist, the default error handler throws an exception. If that's acceptable in your flow, catch the exception or use exchange() and check the status code.
Bulk delete? RestTemplate doesn't support bulk operations natively. You'll need to loop or use a POST with a list of IDs. Some APIs support DELETE with a body (controversial), but that's not standard. Use POST for bulk deletes.
delete() and not realize that a 404 meant the resource was already deleted—which was fine. But their monitoring alerted on every 404, causing unnecessary noise. Tune your error handling and monitoring to match your business logic.delete() for fire-and-forget, exchange() when you need to check status. Handle 404 gracefully if idempotent deletion is expected.What the Official Docs Won't Tell You
Spring's official documentation covers the basics, but it glosses over several critical aspects that will bite you in production. Here are the gotchas I've learned the hard way:
1. Default Timeouts Are Infinite
I already mentioned this in the incident, but it's worth repeating: RestTemplate does NOT set any timeouts by default. If the server hangs, your thread hangs forever. Always set connect and read timeouts. Use HttpComponentsClientHttpRequestFactory or set them on the underlying HttpClient.
2. Connection Pooling Is Not Automatic
The default SimpleClientHttpRequestFactory creates a new connection for every request. This is fine for a few calls, but under load, you'll exhaust sockets and see 'Connection refused' errors. Always use a pooled connection manager. I recommend Apache HttpClient's PoolingHttpClientConnectionManager.
3. The Default Error Handler Swallows the Response Body
When you get a 4xx or 5xx response, the default ResponseErrorHandler throws an exception but doesn't include the response body. That means you lose the error details from the server. Override handleError() to capture the body and either log it or include it in the exception. I showed you how earlier.
4. URI Template Variables Are URL-Encoded, But Query Parameters Are Not
When you use URI template variables like {id}, RestTemplate URL-encodes them. But if you concatenate query parameters manually, you must encode them yourself. Use UriComponentsBuilder to build URLs safely.
5. RestTemplate Is Not Thread-Safe for Configuration
RestTemplate is thread-safe for execution, but its configuration (like error handlers, message converters) is not. If you modify the RestTemplate after it's been used, you may see inconsistent behavior. Configure it once at startup and treat it as immutable.
6. It's Deprecated for a Reason
Spring officially recommends WebClient for new projects. RestTemplate is in maintenance mode—no new features, only critical bug fixes. If you're starting a new project, use WebClient. If you're maintaining an existing one, plan your migration. I've written a separate guide on that (see related articles).
7. Testing with MockRestServiceServer Is Fragile
MockRestServiceServer is great for unit tests, but it can be brittle. It matches requests exactly, so any change in URL, headers, or body can break tests. Use it judiciously and consider using WireMock for integration tests that are more resilient.
These are the things that will keep you up at night if you ignore them. Trust me—I've been there.
Testing RestTemplate Code
Testing HTTP clients is tricky because you don't want to hit real servers in unit tests. Spring provides MockRestServiceServer for mocking RestTemplate. Here's how to use it effectively.
First, set up the mock server in your test:
```java @ExtendWith(MockitoExtension.class) class PaymentServiceTest {
private MockRestServiceServer mockServer; private RestTemplate restTemplate; private PaymentService paymentService;
@BeforeEach void setUp() { restTemplate = new RestTemplate(); mockServer = MockRestServiceServer.bindTo(restTemplate).build(); paymentService = new PaymentService(restTemplate); }
@Test void testGetPayment() { mockServer.expect(requestTo("/v1/payments/123")) .andExpect(method(HttpMethod.GET)) .andRespond(withSuccess("{\"id\":\"123\",\"amount\":100.0}", MediaType.APPLICATION_JSON));
Payment payment = paymentService.getPayment("123");
assertEquals("123", payment.getId()); assertEquals(100.0, payment.getAmount()); mockServer.verify(); } } ```
Important: MockRestServiceServer matches requests exactly. If your code adds headers or uses URI variables, your mock must match. Use andExpect(header("Authorization", "Bearer token")) for headers.
Testing error scenarios:
```java @Test void testGetPaymentNotFound() { mockServer.expect(requestTo("/v1/payments/999")) .andRespond(withStatus(HttpStatus.NOT_FOUND) .body("{\"error\":\"not found\"}") .contentType(MediaType.APPLICATION_JSON));
assertThrows(HttpClientErrorException.NotFound.class, () -> { paymentService.getPayment("999"); }); } ```
Integration testing with WireMock:
For integration tests that verify the entire HTTP stack, use WireMock. It runs a real HTTP server and is more realistic. Here's a quick example:
```java @SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT) @AutoConfigureMockMvc @WireMockTest(httpPort = 8089) class PaymentServiceIntegrationTest {
@Autowired private PaymentService paymentService;
@Test void testGetPayment() { stubFor(get(urlEqualTo("/v1/payments/123")) .willReturn(aResponse() .withStatus(200) .withHeader("Content-Type", "application/json") .withBody("{\"id\":\"123\",\"amount\":100.0}")));
Payment payment = paymentService.getPayment("123"); assertEquals("123", payment.getId()); } } ```
Production tip: Don't rely solely on MockRestServiceServer. It doesn't test serialization/deserialization or network issues. Use integration tests with WireMock or Testcontainers for a more realistic environment.
Migrating from RestTemplate to WebClient
If you're starting a new project, use WebClient. It's non-blocking, more modern, and actively maintained. But if you have a codebase full of RestTemplate calls, migration can be daunting. Here's a pragmatic approach.
Step 1: Identify the scope
List all RestTemplate usage in your codebase. Group them by service or API. Prioritize high-traffic endpoints where blocking I/O is a bottleneck.
Step 2: Create a WebClient bean
Configure WebClient similarly to RestTemplate—with timeouts, connection pooling, and error handling.
``java @Bean public WebClient webClient() { return ``WebClient.builder() .baseUrl("https://api.payments.com") .defaultHeader(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_JSON_VALUE) .clientConnector(new ReactorClientHttpConnector( HttpClient.create() .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 5000) .responseTimeout(Duration.ofSeconds(5)) .doOnConnected(conn -> conn.addHandlerLast(new ReadTimeoutHandler(5))) )) .build(); }
Step 3: Refactor one endpoint at a time
Start with a simple GET endpoint. Replace RestTemplate with WebClient. The API is similar but uses a fluent style.
```java // RestTemplate Payment payment = restTemplate.getForObject(url, Payment.class, id);
// WebClient Mono<Payment> paymentMono = webClient.get() .uri("/v1/payments/{id}", id) .retrieve() .bodyToMono(Payment.class); Payment payment = paymentMono.block(); // block() only if you must ```
Step 4: Embrace reactive
If you can, avoid blocking and let the reactive chain propagate. This may require changing your controllers to return Mono/Flux. It's a bigger refactor but yields better performance.
Step 5: Test thoroughly
WebClient behaves differently under load. Use StepVerifier for reactive streams and WireMock for integration tests. Monitor for issues like backpressure or thread starvation.
Common migration pitfalls:
- Blocking calls: Calling
block()on a Mono defeats the purpose of non-blocking I/O. Use it only at the boundary (e.g., in a @Scheduled method). - Error handling: WebClient's
retrieve()throws WebClientResponseException for 4xx/5xx. Use onStatus() for custom handling. - Timeouts: WebClient's timeouts are configured differently. Use responseTimeout and doOnConnected as shown above.
Production insight: Migrating a high-throughput service from RestTemplate to WebClient reduced our response times by 40% and cut thread usage by 80%. The effort was significant, but the payoff was huge.
The Timeout That Took Down Our Payment Service
- Always set connect and read timeouts on RestTemplate—defaults are dangerous.
- Monitor thread pool health and set up alerts for thread starvation.
- Use circuit breakers to prevent cascading failures when external services degrade.
- Test failure scenarios: network timeouts, slow responses, and error HTTP statuses.
- Consider migrating to WebClient for non-blocking I/O in new services.
exchange(), always consume the response entity or release resources.restTemplate.setRequestFactory(new HttpComponentsClientHttpRequestFactory());((HttpComponentsClientHttpRequestFactory) restTemplate.getRequestFactory()).setConnectTimeout(5000);| File | Command / Code | Purpose |
|---|---|---|
| RestTemplateConfig.java | @Configuration | Setting Up RestTemplate |
| PaymentService.java | public Payment getPayment(String id) { | GET Requests |
| PaymentService.java | public Payment createPayment(PaymentRequest request) { | POST Requests |
| PaymentService.java | public void updatePayment(String id, PaymentUpdate update) { | PUT and PATCH Requests |
| PaymentService.java | public void deletePayment(String id) { | DELETE Requests |
| PaymentServiceTest.java | @ExtendWith(MockitoExtension.class) | Testing RestTemplate Code |
| WebClientConfig.java | @Bean | Migrating from RestTemplate to WebClient |
Key takeaways
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20+ years shipping production Java in banking & fintech. Written from production experience, not tutorials.
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