java HTTP请求怎么发送

在 Java 中发送 HTTP 请求有多种方式，下面按常见程度和使用场景给你介绍几种主流方法，并附上示例。

一、Java 11+ 原生方式（推荐，无需额外依赖）

Java 11 引入了 java.net.http.HttpClient，官方推荐。

1️⃣ 发送 GET 请求

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;

public class HttpExample {
    public static void main(String[] args) throws Exception {
        HttpClient client = HttpClient.newHttpClient();

        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create("https://jsonplaceholder.typicode.com/posts/1"))
                .GET()
                .build();

        HttpResponse<String> response =
                client.send(request, HttpResponse.BodyHandlers.ofString());

        System.out.println(response.statusCode());
        System.out.println(response.body());
    }
}

2️⃣ 发送 POST 请求（JSON）

HttpRequest request = HttpRequest.newBuilder()
        .uri(URI.create("https://jsonplaceholder.typicode.com/posts"))
        .header("Content-Type", "application/json")
        .POST(HttpRequest.BodyPublishers.ofString(
                "{\"title\":\"foo\",\"body\":\"bar\",\"userId\":1}"
        ))
        .build();

HttpResponse<String> response =
        client.send(request, HttpResponse.BodyHandlers.ofString());

System.out.println(response.body());

二、Apache HttpClient（老项目常用）

添加依赖（Maven）

<dependency>
    <groupId>org.apache.httpcomponents</groupId>
    <artifactId>httpclient</artifactId>
    <version>4.5.14</version>
</dependency>

GET 示例

CloseableHttpClient client = HttpClients.createDefault();
HttpGet get = new HttpGet("https://jsonplaceholder.typicode.com/posts/1");

CloseableHttpResponse response = client.execute(get);
String result = EntityUtils.toString(response.getEntity());
System.out.println(result);

三、Spring 项目（最常用）

1️⃣ RestTemplate（老方式，仍可用）

RestTemplate restTemplate = new RestTemplate();
String result = restTemplate.getForObject(
        "https://jsonplaceholder.typicode.com/posts/1",
        String.class
);

2️⃣ WebClient（Spring WebFlux，推荐新项目）

WebClient client = WebClient.create();

String result = client.get()
        .uri("https://jsonplaceholder.typicode.com/posts/1")
        .retrieve()
        .bodyToMono(String.class)
        .block();

四、OkHttp（Android / 高性能场景）

OkHttpClient client = new OkHttpClient();

Request request = new Request.Builder()
        .url("https://jsonplaceholder.typicode.com/posts/1")
        .build();

Response response = client.newCall(request).execute();
System.out.println(response.body().string());

五、如何选择？

如果你有具体场景（比如带 token、文件上传、异步请求、Spring Boot），可以告诉我，我给你写完整示例。