java post格式发送application/x-www-form-urlencoded

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONObject;
import org.apache.http.*;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.entity.ContentType;
import org.apache.http.entity.StringEntity;
import org.apache.http.entity.mime.MultipartEntityBuilder;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.message.BasicHeader;
import org.apache.http.protocol.HTTP;
import org.apache.http.util.EntityUtils;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import java.io.*;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;
import java.util.Map;

public class HttpUtil {
    private final static Logger logger = LogManager.getLogger(HttpUtil.class);

    public static String sendPost(String url, String param) {
        String result = "";
        try {
            URL httpurl = new URL(url);
            HttpURLConnection httpConn = (HttpURLConnection) httpurl.openConnection();
            httpConn.setRequestProperty("Content-Type", "application/x-www-form-urlencoded");
            httpConn.setDoOutput(true);
            httpConn.setDoInput(true);
            PrintWriter out = new PrintWriter(new OutputStreamWriter(httpConn.getOutputStream(), StandardCharsets.UTF_8));
            out.print(param);
            out.flush();
            out.close();
            BufferedReader in = new BufferedReader(new InputStreamReader(httpConn.getInputStream(), StandardCharsets.UTF_8));
            String line;
            while ((line = in.readLine()) != null) {
                result += line;
            }
            in.close();
        } catch (Exception e) {
            System.out.println(e);
            logger.error(e);
        }
        return result;
    }
}