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java如何发送http请求

2026-02-05 08:41:06Java

发送HTTP请求的方法

Java中发送HTTP请求有多种方式，以下是几种常见的方法：

使用`HttpURLConnection`

HttpURLConnection是Java标准库中的类，适用于简单的HTTP请求。

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

public class HttpUrlConnectionExample {
    public static void main(String[] args) throws Exception {
        URL url = new URL("https://example.com/api");
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("GET");

        int responseCode = connection.getResponseCode();
        System.out.println("Response Code: " + responseCode);

        BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        String inputLine;
        StringBuilder response = new StringBuilder();

        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();

        System.out.println(response.toString());
    }
}

使用`HttpClient`（Java 11+）

Java 11引入了新的HttpClient，提供更现代的API。

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

public class HttpClientExample {
    public static void main(String[] args) throws Exception {
        HttpClient client = HttpClient.newHttpClient();
        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create("https://example.com/api"))
                .build();

        HttpResponse<String> response = client.send(request, HttpResponse.BodyHandlers.ofString());
        System.out.println(response.body());
    }
}

使用第三方库（如Apache HttpClient）

Apache HttpClient是广泛使用的第三方库，功能强大。

import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

public class ApacheHttpClientExample {
    public static void main(String[] args) throws Exception {
        CloseableHttpClient client = HttpClients.createDefault();
        HttpGet request = new HttpGet("https://example.com/api");

        CloseableHttpResponse response = client.execute(request);
        System.out.println(EntityUtils.toString(response.getEntity()));
        response.close();
        client.close();
    }
}

使用Spring的`RestTemplate`

Spring框架提供了RestTemplate，适合Spring项目。

import org.springframework.web.client.RestTemplate;

public class RestTemplateExample {
    public static void main(String[] args) {
        RestTemplate restTemplate = new RestTemplate();
        String response = restTemplate.getForObject("https://example.com/api", String.class);
        System.out.println(response);
    }
}

使用OkHttp

OkHttp是另一个流行的第三方库，性能优异。

import okhttp3.OkHttpClient;
import okhttp3.Request;
import okhttp3.Response;

public class OkHttpExample {
    public static void main(String[] args) throws Exception {
        OkHttpClient client = new OkHttpClient();
        Request request = new Request.Builder()
                .url("https://example.com/api")
                .build();

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