在Java开发中，经常需要调用第三方接口来获取数据或执行某些服务。本文将详细介绍如何使用Java调用第三方接口，包括使用JDK自带的HttpURLConnection类和流行的第三方库如OkHttp和Apache HttpClient。
一、使用HttpURLConnection调用第三方接口
1. GET请求示例
import java.io.BufferedReader;import java.io.InputStreamReader;import java.net.HttpURLConnection;import java.net.URL;public class ThirdPartyApiCaller { public static void main(String[] args) { try { // 创建URL对象 URL url = new URL("https://api.example.com/data"); // 创建HttpURLConnection对象 HttpURLConnection connection = (HttpURLConnection) url.openConnection(); // 设置请求方法为GET connection.setRequestMethod("GET"); // 发送请求并获取响应码 int responseCode = connection.getResponseCode(); // 检查响应码 if (responseCode == HttpURLConnection.HTTP_OK) { // 读取响应内容 BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream())); StringBuilder response = new StringBuilder(); String line; while ((line = reader.readLine()) != null) { response.append(line); } reader.close(); // 处理响应内容 System.out.println(response.toString()); } else { // 处理错误响应 System.out.println("请求失败,响应码: " + responseCode); } // 关闭连接 connection.disconnect(); } catch (Exception e) { e.printStackTrace(); } }}2. POST请求示例
import java.io.DataOutputStream;import java.io.InputStreamReader;import java.io.BufferedReader;import java.net.HttpURLConnection;import java.net.URL;import java.nio.charset.StandardCharsets;public class ThirdPartyApiCaller { public static void main(String[] args) { try { // 创建URL对象 URL url = new URL("https://api.example.com/submit"); // 创建HttpURLConnection对象 HttpURLConnection connection = (HttpURLConnection) url.openConnection(); // 设置请求方法为POST connection.setRequestMethod("POST"); // 设置请求头 connection.setRequestProperty("Content-Type", "application/json"); // 启用输出流 connection.setDoOutput(true); // 创建请求体 String requestBody = "{\"key\":\"value\"}"; // 将请求体写入输出流 DataOutputStream outputStream = new DataOutputStream(connection.getOutputStream()); outputStream.write(requestBody.getBytes(StandardCharsets.UTF_8)); outputStream.flush(); outputStream.close(); // 发送请求并获取响应码 int responseCode = connection.getResponseCode(); // 检查响应码 if (responseCode == HttpURLConnection.HTTP_OK) { // 读取响应内容 BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream())); StringBuilder response = new StringBuilder(); String line; while ((line = reader.readLine()) != null) { response.append(line); } reader.close(); // 处理响应内容 System.out.println(response.toString()); } else { // 处理错误响应 System.out.println("请求失败,响应码: " + responseCode); } // 关闭连接 connection.disconnect(); } catch (Exception e) { e.printStackTrace(); } }}二、使用OkHttp库调用第三方接口
OkHttp是一个强大的HTTP客户端库，用于发送和接收HTTP请求。以下是如何使用OkHttp发送POST请求的示例：
import okhttp3.*;import java.io.IOException;public class OkHttpExample { public static void main(String[] args) throws IOException { OkHttpClient client = new OkHttpClient(); String url = "https://api.example.com/submit"; String json = "{\"key\":\"value\"}"; MediaType JSON = MediaType.parse("application/json; charset=utf-8"); RequestBody body = RequestBody.create(json, JSON);