HttpURLConnection 发送get 请求json

以下是使用HttpURLConnection发送GET请求并获取JSON响应的示例代码：

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) {
        String url = "https://jsonplaceholder.typicode.com/todos/1";
        try {
            URL urlObj = new URL(url);
            HttpURLConnection conn = (HttpURLConnection) urlObj.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();
        }
    }
}

在此示例中，我们使用HttpURLConnection打开URL并设置请求方法为GET。我们还设置了Accept标头以指示服务器返回JSON响应。如果响应代码不是200，则抛出运行时异常。最后，我们读取响应的输入流并打印JSON响应。