Java调用第三方http接口的常用方式总结

在Java中，调用第三方HTTP接口是一种常见的需求，为了实现这一目标，Java提供了多种方式，包括使用原生的HttpURLConnection、Apache HttpClient、OkHttp等库，本文将对Java调用第三方HTTP接口的常用方式进行总结。

1、使用HttpURLConnection

HttpURLConnection是Java标准库中的一个类，用于发送HTTP请求和接收HTTP响应，以下是一个简单的示例：

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 {
        String url = "http://api.example.com/data";
        URL obj = new URL(url);
        HttpURLConnection connection = (HttpURLConnection) obj.openConnection();
        connection.setRequestMethod("GET");
        int responseCode = connection.getResponseCode();
        System.out.println("Response Code: " + responseCode);
        BufferedReader in = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        String inputLine;
        StringBuffer response = new StringBuffer();
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();
        System.out.println(response.toString());
    }
}

2、使用Apache HttpClient

Apache HttpClient是一个开源的HTTP客户端库，提供了丰富的功能和灵活的配置选项，以下是一个简单的示例：

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
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 httpClient = HttpClients.createDefault();
        HttpGet httpGet = new HttpGet("http://api.example.com/data");
        HttpResponse httpResponse = httpClient.execute(httpGet);
        HttpEntity httpEntity = httpResponse.getEntity();
        String response = EntityUtils.toString(httpEntity, "UTF-8");
        System.out.println(response);
    }
}

3、使用OkHttp

OkHttp是一个高效且易用的HTTP客户端库，由Square公司开发，以下是一个简单的示例：

import okhttp3.*;
import java.io.IOException;
import java.util.concurrent.TimeUnit;
public class OkHttpExample {
    public static void main(String[] args) throws IOException {
        OkHttpClient client = new OkHttpClient();
        MediaType mediaType = MediaType.parse("application/json");
        RequestBody body = RequestBody.create(mediaType, "{}");
        Request request = new Request.Builder()
                .url("http://api.example.com/data")
                .post(body)
                .addHeader("User-Agent", "OkHttp Example")
                .build();
        try (Response response = client.newCall(request).execute()) {
            if (!response.isSuccessful()) throw new IOException("Unexpected code " + response);
            ResponseBody responseBody = response.body();
            System.out.println(responseBody.string());
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            client = null; // 释放资源，避免内存泄漏
        }
    }
}

问题与解答：

1、Q: 在使用Apache HttpClient时，如何设置超时时间？

A: 可以通过RequestConfig对象设置超时时间，RequestConfig requestConfig = RequestConfig.custom().setConnectTimeout(5000).setSocketTimeout(5000).build();，然后将requestConfig应用到HttpGet或HttpPost对象上。

2、Q: 在使用OkHttp时，如何设置代理服务器？