java http post json对象请求

在Java中发送HTTP POST请求并携带JSON对象，通常会用到`HttpURLConnection`、`HttpClient`或者第三方库如`Apache HttpClient`或`OkHttp`。这里我会演示使用`HttpURLConnection`的基本示例：

import java.io.OutputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import org.json.JSONObject;

public JSONObject sendPostJson(String url, JSONObject json) throws Exception {
    URL obj = new URL(url);
    HttpURLConnection con = (HttpURLConnection) obj.openConnection();
    con.setRequestMethod("POST");
    con.setRequestProperty("Content-Type", "application/json; charset=UTF-8");

    // Write the JSON object to the request body
    OutputStream os = con.getOutputStream();
    byte[] jsonBytes = json.toString().getBytes("UTF-8");
    os.write(jsonBytes);
    os.flush();
    os.close();

    int responseCode = con.getResponseCode();
    if (responseCode == HttpURLConnection.HTTP_OK) {
        return readJson(con.getInputStream()); // assuming you have a method to parse JSON from InputStream
    } else {
        throw new RuntimeException("Failed : HTTP error code : " + responseCode);
    }
}

private JSONObject readJson(InputStream is) throws Exception {
    // Parse the JSON content here using a library like Jackson or Gson
    // For example with Jackson:
    ObjectMapper mapper = new ObjectMapper();
    return mapper.readValue(is, JSONObject.class);
}