Create Single Invoice

                        
                            import com.google.gson.Gson;
                            import org.apache.commons.codec.binary.Hex;
                            import javax.crypto.Mac;
                            import javax.crypto.spec.SecretKeySpec;
                            import java.io.BufferedReader;
                            import java.io.InputStreamReader;
                            import java.io.OutputStream;
                            import java.net.HttpURLConnection;
                            import java.net.URL;
                            import java.nio.charset.StandardCharsets;
                            import java.util.ArrayList;
                            import java.util.TreeMap;

                            public class CreateSingleInvoice {
                                private static final String privateKey = "OPAYPRV16357783346230.07653446106051542";
                                private static final String endpoint = "https://sandboxapi.opaycheckout.com";
                                private static final String merchantId = "256612345678901";

                                public static void main(String[] args) throws Exception {
                                    String addr = endpoint + "/api/v1/international/invoice/createSingleInvoice";
                                    Gson gson = new Gson();
                                    TreeMap order = new TreeMap<>();
                                    TreeMap amount = new TreeMap<>();
                                    amount.put("currency","EGP");
                                    amount.put("total",new Integer(400));
                                    order.put("amount",amount);
                                    order.put("country","EG");
                                    TreeMap customer = new TreeMap<>();
                                    customer.put("customerEmail","10379xxxx@xx.com");
                                    customer.put("customerMobile","+201110024320");
                                    customer.put("customerName","customerName");
                                    order.put("customer",customer);
                                    order.put("description","description");
                                    order.put("dueTime",1698363138);
                                    order.put("lang","AR");
                                    order.put("name","invoice_name");
                                    order.put("notifyMethod","BOTH");
                                    ArrayList productList = new ArrayList<>();
                                    TreeMap product = new TreeMap<>();
                                    product.put("merchantProductNo","1010");
                                    product.put("quantity",new Integer(2));
                                    productList.add(product);
                                    order.put("productList",productList);
                                    order.put("relationProduct",true);
                                    TreeMap serviceFee = new TreeMap<>();
                                    customer.put("currency","EGP");
                                    customer.put("feeRate","1");
                                    customer.put("fixedFee","1");
                                    order.put("serviceFee",serviceFee);

                                    String requestBody = gson.toJson(order);
                                    System.out.println("--request:");
                                    System.out.println(requestBody);
                                    String oPaySignature = hmacSHA512(requestBody, privateKey);
                                    System.out.println("--signature:");
                                    System.out.println(oPaySignature);

                                    URL url = new URL(addr);
                                    HttpURLConnection con = (HttpURLConnection)url.openConnection();
                                    con.setRequestMethod("POST");
                                    con.setRequestProperty("Content-Type", "application/json; utf-8");
                                    con.setRequestProperty("Authorization", "Bearer "+oPaySignature);
                                    con.setRequestProperty("MerchantId", merchantId);
                                    con.setDoOutput(true);
                                    OutputStream os = con.getOutputStream();
                                    byte[] input = requestBody.getBytes(StandardCharsets.UTF_8);
                                    os.write(input, 0, input.length);
                                    BufferedReader br = new BufferedReader(new InputStreamReader(con.getInputStream(), StandardCharsets.UTF_8));
                                    StringBuilder response = new StringBuilder();
                                    String responseLine = null;
                                    while ((responseLine = br.readLine()) != null) {
                                        response.append(responseLine.trim());
                                    }

                                    System.out.println("--response:");
                                    System.out.println(response.toString());
                                    //close your stream and connection
                                }

                                public static String hmacSHA512(final String data, final String secureKey) throws Exception{
                                    byte[] bytesKey = secureKey.getBytes();
                                    final SecretKeySpec secretKey = new SecretKeySpec(bytesKey, "HmacSHA512");
                                    Mac mac = Mac.getInstance("HmacSHA512");
                                    mac.init(secretKey);
                                    final byte[] macData = mac.doFinal(data.getBytes());
                                    byte[] hex = new Hex().encode(macData);
                                    return new String(hex, StandardCharsets.UTF_8);
                                }
                            }