Java实现调用第三方api get和post请求

Java可以使用HttpURLConnection或者HttpClient等类库来实现调用第三方API的GET和POST请求。

GET请求示例：

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

public class GetRequestExample {

    public static void main(String[] args) {

        try {
            URL url = new URL("https://api.example.com/data");
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("GET");
            conn.setRequestProperty("Accept", "application/json");

            if (conn.getResponseCode() != 200) {
                throw new RuntimeException("Failed : HTTP error code : " + conn.getResponseCode());
            }

            BufferedReader br = new BufferedReader(new InputStreamReader((conn.getInputStream())));

            String output;
            System.out.println("Output from Server .... \n");
            while ((output = br.readLine()) != null) {
                System.out.println(output);
            }

            conn.disconnect();

        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

POST请求示例：

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.io.OutputStream;
import java.nio.charset.StandardCharsets;

public class PostRequestExample {

    public static void main(String[] args) {

        try {
            URL url = new URL("https://api.example.com/data");
            HttpURLConnection conn = (HttpURLConnection) url.openConnection();
            conn.setRequestMethod("POST");
            conn.setRequestProperty("Content-Type", "application/json");
            conn.setRequestProperty("Accept", "application/json");
            conn.setDoOutput(true);

            String requestBody = "{\"name\":\"John\",\"age\":30,\"city\":\"New York\"}";

            try (OutputStream os = conn.getOutputStream()) {
                byte[] input = requestBody.getBytes(StandardCharsets.UTF_8);
                os.write(input, 0, input.length);
            }

            if (conn.getResponseCode() != 200) {
                throw new RuntimeException("Failed : HTTP error code : " + conn.getResponseCode());
            }

            BufferedReader br = new BufferedReader(new InputStreamReader((conn.getInputStream())));

            String output;
            System.out.println("Output from Server .... \n");
            while ((output = br.readLine()) != null) {
                System.out.println(output);
            }

            conn.disconnect();

        } catch (Exception e) {
            e.printStackTrace();
        }

    }

}

这里以调用JSON格式的API接口为例，请求头中设置了Accept为"application/json"，请求体中的数据也是JSON格式的。POST请求需要设置请求方法为"POST"，同时需要设置请求头中的Content-Type为"application/json"，并且需要将请求体数据写入到请求输出流中。