生成一个post接口调用的java代码 四个参数AccessKey ,sign,timestamp,nonce的参数位置是QUERY HEADER是hsPartyId body是json

以下是一个使用Java的HttpURLConnection类生成一个POST请求的示例代码，其中AccessKey，sign，timestamp和nonce分别作为查询参数，请求头和请求体中的参数：

import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

public class ExamplePostRequest {

    private static final String ACCESS_KEY = "your_access_key_here";
    private static final String SECRET_KEY = "your_secret_key_here";
    private static final String BASE_URL = "http://example.com/api/post";

    public static void main(String[] args) throws Exception {
        String requestBody = "{\"key1\":\"value1\",\"key2\":\"value2\"}";
        String hsPartyId = "your_hsparty_id_here";
        String timestamp = Long.toString(System.currentTimeMillis() / 1000L);
        String nonce = generateNonce();

        // Generate the signature
        String sign = generateSignature(hsPartyId, timestamp, nonce, requestBody);

        // Build the query string
        String queryString = String.format("AccessKey=%s&sign=%s&timestamp=%s&nonce=%s",
                ACCESS_KEY, sign, timestamp, nonce);

        // Build the request URL
        String requestUrl = String.format("%s?%s", BASE_URL, queryString);

        // Build the request headers
        Map<String, String> headers = new HashMap<>();
        headers.put("hsPartyId", hsPartyId);

        // Send the POST request
        String response = sendPostRequest(requestUrl, headers, requestBody);

        // Print the response
        System.out.println(response);
    }

    private static String sendPostRequest(String requestUrl, Map<String, String> headers, String requestBody)
            throws Exception {
        URL url = new URL(requestUrl);
        HttpURLConnection connection = (HttpURLConnection) url.openConnection();

        // Set HTTP method to POST
        connection.setRequestMethod("POST");

        // Set request headers
        for (Map.Entry<String, String> entry : headers.entrySet()) {
            connection.setRequestProperty(entry.getKey(), entry.getValue());
        }

        // Set content type and length
        connection.setRequestProperty("Content-Type", "application/json");
        connection.setRequestProperty("Content-Length", Integer.toString(requestBody.getBytes().length));

        // Enable output and input
        connection.setDoOutput(true);
        connection.setDoInput(true);

        // Send request body
        DataOutputStream outputStream = new DataOutputStream(connection.getOutputStream());
        outputStream.writeBytes(requestBody);
        outputStream.flush();
        outputStream.close();

        // Read response
        BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
        StringBuilder responseBuilder = new StringBuilder();
        String line;
        while ((line = reader.readLine()) != null) {
            responseBuilder.append(line);
        }
        reader.close();

        return responseBuilder.toString();
    }

    private static String generateNonce() {
        // Generate a random alphanumeric string of length 16
        String characters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
        StringBuilder nonceBuilder = new StringBuilder();
        Random random = new Random();
        for (int i = 0; i < 16; i++) {
            int index = random.nextInt(characters.length());
            char character = characters.charAt(index);
            nonceBuilder.append(character);
        }
        return nonceBuilder.toString();
    }

    private static String generateSignature(String hsPartyId, String timestamp, String nonce, String requestBody)
            throws NoSuchAlgorithmException {
        // Concatenate the hsPartyId, timestamp, nonce, and requestBody
        String concatenatedString = hsPartyId + timestamp + nonce + requestBody;

        // Generate the SHA-256 hash of the concatenated string using the secret key
        MessageDigest messageDigest = MessageDigest.getInstance("SHA-256");
        messageDigest.update(concatenatedString.getBytes());
        messageDigest.update(SECRET_KEY.getBytes());
        byte[] digest = messageDigest.digest();

        // Convert the hash to a hexadecimal string
        StringBuilder signatureBuilder = new StringBuilder();
        for (byte b : digest) {
            String hex = Integer.toHexString(0xff & b);
            if (hex.length() == 1) {
                signatureBuilder.append('0');
            }
            signatureBuilder.append(hex);
        }
        return signatureBuilder.toString();
    }
}