Java案例如何实现网络请求？

wen python案例 2026-07-22 1

本文目录导读：

Java案例如何实现网络请求？

使用 HttpURLConnection（原生方式）
使用 Apache HttpClient
使用 OkHttp
使用 Spring RestTemplate（Spring 框架）
使用 Java 11+ HttpClient（内置）
总结与建议

在Java中实现网络请求有多种方式,以下是最常用的几种方法及完整示例。

使用 HttpURLConnection（原生方式）

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;
public class HttpURLConnectionExample {
    // GET请求
    public static String sendGet(String urlStr) throws Exception {
        URL url = new URL(urlStr);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        // 设置请求方法
        connection.setRequestMethod("GET");
        connection.setRequestProperty("Content-Type", "application/json");
        connection.setConnectTimeout(5000);
        connection.setReadTimeout(5000);
        // 获取响应码
        int responseCode = connection.getResponseCode();
        System.out.println("响应码: " + responseCode);
        // 读取响应
        BufferedReader reader = new BufferedReader(
            new InputStreamReader(connection.getInputStream(), StandardCharsets.UTF_8));
        StringBuilder response = new StringBuilder();
        String line;
        while ((line = reader.readLine()) != null) {
            response.append(line);
        }
        reader.close();
        return response.toString();
    }
    // POST请求
    public static String sendPost(String urlStr, String jsonBody) throws Exception {
        URL url = new URL(urlStr);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();
        connection.setRequestMethod("POST");
        connection.setRequestProperty("Content-Type", "application/json");
        connection.setDoOutput(true);
        connection.setConnectTimeout(5000);
        connection.setReadTimeout(5000);
        // 写入请求体
        try (OutputStream os = connection.getOutputStream()) {
            byte[] input = jsonBody.getBytes(StandardCharsets.UTF_8);
            os.write(input, 0, input.length);
        }
        // 获取响应
        int responseCode = connection.getResponseCode();
        BufferedReader reader = new BufferedReader(
            new InputStreamReader(connection.getInputStream(), StandardCharsets.UTF_8));
        StringBuilder response = new StringBuilder();
        String line;
        while ((line = reader.readLine()) != null) {
            response.append(line);
        }
        reader.close();
        return response.toString();
    }
    public static void main(String[] args) {
        try {
            // GET请求示例
            String getResponse = sendGet("http://jsonplaceholder.typicode.com/posts/1");
            System.out.println("GET响应: " + getResponse);
            // POST请求示例
            String jsonBody = "{\"title\": \"foo\", \"body\": \"bar\", \"userId\": 1}";
            String postResponse = sendPost("http://jsonplaceholder.typicode.com/posts", jsonBody);
            System.out.println("POST响应: " + postResponse);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

使用 Apache HttpClient

首先添加 Maven 依赖：

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

import org.apache.http.HttpResponse;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
public class HttpClientExample {
    // GET请求
    public static String sendGet(String url) throws Exception {
        try (CloseableHttpClient client = HttpClients.createDefault()) {
            HttpGet request = new HttpGet(url);
            request.setHeader("Content-Type", "application/json");
            HttpResponse response = client.execute(request);
            int statusCode = response.getStatusLine().getStatusCode();
            System.out.println("响应码: " + statusCode);
            return EntityUtils.toString(response.getEntity());
        }
    }
    // POST请求
    public static String sendPost(String url, String jsonBody) throws Exception {
        try (CloseableHttpClient client = HttpClients.createDefault()) {
            HttpPost request = new HttpPost(url);
            request.setHeader("Content-Type", "application/json");
            request.setEntity(new StringEntity(jsonBody, "UTF-8"));
            HttpResponse response = client.execute(request);
            return EntityUtils.toString(response.getEntity());
        }
    }
    public static void main(String[] args) {
        try {
            String response = sendGet("http://jsonplaceholder.typicode.com/posts/1");
            System.out.println("响应: " + response);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

使用 OkHttp

添加 Maven 依赖：

<dependency>
    <groupId>com.squareup.okhttp3</groupId>
    <artifactId>okhttp</artifactId>
    <version>4.12.0</version>
</dependency>

import okhttp3.*;
import java.io.IOException;
public class OkHttpExample {
    private static final OkHttpClient client = new OkHttpClient();
    // GET请求
    public static String sendGet(String url) throws IOException {
        Request request = new Request.Builder()
                .url(url)
                .addHeader("Content-Type", "application/json")
                .build();
        try (Response response = client.newCall(request).execute()) {
            if (!response.isSuccessful()) {
                throw new IOException("请求失败: " + response.code());
            }
            return response.body().string();
        }
    }
    // POST请求
    public static String sendPost(String url, String jsonBody) throws IOException {
        MediaType JSON = MediaType.get("application/json; charset=utf-8");
        RequestBody body = RequestBody.create(jsonBody, JSON);
        Request request = new Request.Builder()
                .url(url)
                .post(body)
                .build();
        try (Response response = client.newCall(request).execute()) {
            return response.body().string();
        }
    }
    // 异步请求
    public static void sendAsyncGet(String url) {
        Request request = new Request.Builder()
                .url(url)
                .build();
        client.newCall(request).enqueue(new Callback() {
            @Override
            public void onFailure(Call call, IOException e) {
                e.printStackTrace();
            }
            @Override
            public void onResponse(Call call, Response response) throws IOException {
                System.out.println("异步响应: " + response.body().string());
            }
        });
    }
    public static void main(String[] args) {
        try {
            String response = sendGet("http://jsonplaceholder.typicode.com/posts/1");
            System.out.println("响应: " + response);
            // 异步请求
            sendAsyncGet("http://jsonplaceholder.typicode.com/posts/1");
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

使用 Spring RestTemplate（Spring 框架）

添加 Maven 依赖：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

import org.springframework.http.*;
import org.springframework.web.client.RestTemplate;
public class RestTemplateExample {
    public static String sendGet(String url) {
        RestTemplate restTemplate = new RestTemplate();
        ResponseEntity<String> response = restTemplate.getForEntity(url, String.class);
        return response.getBody();
    }
    public static String sendPost(String url, String jsonBody) {
        RestTemplate restTemplate = new RestTemplate();
        HttpHeaders headers = new HttpHeaders();
        headers.setContentType(MediaType.APPLICATION_JSON);
        HttpEntity<String> request = new HttpEntity<>(jsonBody, headers);
        ResponseEntity<String> response = restTemplate.postForEntity(url, request, String.class);
        return response.getBody();
    }
    public static void main(String[] args) {
        String response = sendGet("http://jsonplaceholder.typicode.com/posts/1");
        System.out.println("响应: " + response);
    }
}

使用 Java 11+ HttpClient（内置）

import java.net.URI;
import java.net.http.HttpClient;
import java.net.http.HttpRequest;
import java.net.http.HttpResponse;
import java.time.Duration;
public class JavaHttpClientExample {
    private static final HttpClient client = HttpClient.newBuilder()
            .connectTimeout(Duration.ofSeconds(5))
            .build();
    // GET请求
    public static String sendGet(String url) throws Exception {
        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create(url))
                .header("Content-Type", "application/json")
                .timeout(Duration.ofSeconds(5))
                .GET()
                .build();
        HttpResponse<String> response = client.send(request, 
            HttpResponse.BodyHandlers.ofString());
        return response.body();
    }
    // POST请求
    public static String sendPost(String url, String jsonBody) throws Exception {
        HttpRequest request = HttpRequest.newBuilder()
                .uri(URI.create(url))
                .header("Content-Type", "application/json")
                .timeout(Duration.ofSeconds(5))
                .POST(HttpRequest.BodyPublishers.ofString(jsonBody))
                .build();
        HttpResponse<String> response = client.send(request, 
            HttpResponse.BodyHandlers.ofString());
        return response.body();
    }
    public static void main(String[] args) {
        try {
            String response = sendGet("http://jsonplaceholder.typicode.com/posts/1");
            System.out.println("响应: " + response);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

总结与建议

方式	优点	缺点	适用场景
HttpURLConnection	无需第三方依赖	API较原始，代码量多	简单请求
Apache HttpClient	功能完善，稳定性高	需要引入依赖	企业级应用
OkHttp	性能优秀，支持HTTP/2	需要引入依赖	移动端/高性能场景
Spring RestTemplate	与Spring集成好	依赖Spring框架	Spring项目
Java HttpClient(11+)	内置，API现代化	仅支持Java11+	Java11+项目

建议：

如果使用Spring Boot，优先选择 RestTemplate 或 WebClient
新项目推荐使用 OkHttp 或 Java 11+ HttpClient
简单的测试场景可以使用 HttpURLConnection