如何通过Spring RestTemplate发送带Raw数据的POST请求

Hey there! Let's fix your code first, then break down the proper approach for sending raw JSON data via RestTemplate.

What's Wrong with Your Current Code? #

Looking at your snippet, here are the key issues:

• You're trying to use a MultiValueMap (designed for form-encoded data like x-www-form-urlencoded) instead of sending your JSON object directly as the request body.
• You’ve built a JsonObject but aren’t actually passing it as the payload to your POST request.
• You’re missing the final step of creating an HttpEntity (combining headers and body) and executing the request with RestTemplate.

Corrected Code Implementation #

Let’s adjust your code to properly send raw JSON. We’ll use javax.json.JsonObject for this example (adjust imports if you’re using Gson or Jackson):

import org.springframework.http.HttpEntity;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.http.ResponseEntity;
import org.springframework.web.client.RestTemplate;
import javax.json.Json;
import javax.json.JsonObject;

// Your existing variables (appId, etc.) should be defined here

// 1. Set up headers with JSON content type
HttpHeaders headers = new HttpHeaders();
headers.setContentType(MediaType.APPLICATION_JSON);

// 2. Build your raw JSON payload
JsonObject properties = Json.createObjectBuilder()
    .add("app_id", appId)
    .add("identity", "TestAPI")
    .add("event", "TestComplete") // Completed the truncated event name
    // Add any additional properties you need here
    .build();

// 3. Create HttpEntity combining headers and JSON body
HttpEntity<String> requestEntity = new HttpEntity<>(properties.toString(), headers);

// 4. Send the POST request using RestTemplate
RestTemplate restTemplate = new RestTemplate();
String apiUrl = "https://your-target-api-url.com/endpoint"; // Replace with your actual API URL

// Option 1: Get just the response body as a String
String responseBody = restTemplate.postForObject(apiUrl, requestEntity, String.class);

// Option 2: Get full response details (status code, headers, body)
ResponseEntity<String> responseEntity = restTemplate.postForEntity(apiUrl, requestEntity, String.class);
System.out.println("Response Status: " + responseEntity.getStatusCode());
System.out.println("Response Body: " + responseEntity.getBody());

Alternative: Using a POJO for Type Safety #

For cleaner, more maintainable code (especially with complex payloads), use a POJO (Plain Old Java Object) instead of manual JSON building:

1. Create a class representing your payload:

public class EventPayload {
    private String app_id;
    private String identity;
    private String event;

    // Getters and setters (use Lombok @Data to auto-generate these if you prefer)
    public String getApp_id() { return app_id; }
    public void setApp_id(String app_id) { this.app_id = app_id; }
    public String getIdentity() { return identity; }
    public void setIdentity(String identity) { this.identity = identity; }
    public String getEvent() { return event; }
    public void setEvent(String event) { this.event = event; }
}

2. Use the POJO in your RestTemplate code:

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

EventPayload payload = new EventPayload();
payload.setApp_id(appId);
payload.setIdentity("TestAPI");
payload.setEvent("TestComplete");

HttpEntity<EventPayload> requestEntity = new HttpEntity<>(payload, headers);

RestTemplate restTemplate = new RestTemplate();
String apiUrl = "https://your-target-api-url.com/endpoint";

// RestTemplate automatically serializes the POJO to JSON
ResponseEntity<String> response = restTemplate.postForEntity(apiUrl, requestEntity, String.class);

Key Takeaways #

• When sending raw JSON, don’t use MultiValueMap—it’s for form data. Instead, pass your JSON (as a String or POJO) directly as the request body.
• Always set the Content-Type header to MediaType.APPLICATION_JSON so the server knows to parse the body as JSON.
• Use HttpEntity to wrap your headers and body together before passing to RestTemplate.

内容的提问来源于stack exchange，提问作者Bhargav