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<code>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);