Java http工具类，post请求发送json参数

下面是一个Java的Http工具类，可以用于发送POST请求并且发送JSON参数：

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

public class HttpUtils {
    public static String post(String url, String json) throws Exception {
        URL obj = new URL(url);
        HttpURLConnection con = (HttpURLConnection) obj.openConnection();

        // 设置请求方法为POST
        con.setRequestMethod("POST");

        // 设置请求头
        con.setRequestProperty("Content-Type", "application/json;charset=UTF-8");
        con.setRequestProperty("Accept", "application/json");

        // 开启输出流
        con.setDoOutput(true);

        // 发送请求
        con.getOutputStream().write(json.getBytes(StandardCharsets.UTF_8));

        // 获取响应状态码
        int responseCode = con.getResponseCode();

        // 读取响应内容
        BufferedReader in = new BufferedReader(new InputStreamReader(con.getInputStream()));
        String inputLine;
        StringBuilder response = new StringBuilder();
        while ((inputLine = in.readLine()) != null) {
            response.append(inputLine);
        }
        in.close();

        if (responseCode == HttpURLConnection.HTTP_OK) {
            return response.toString();
        } else {
            throw new Exception("HTTP请求失败，" + responseCode + " " + con.getResponseMessage());
        }
    }
}

使用方法：

String url = "http://example.com/api";
String json = "{\"key\":\"value\"}";
String response = HttpUtils.post(url, json);
System.out.println(response);