如何用Java开发付款功能

<dependency>
    <groupId>com.alipay.sdk</groupId>
    <artifactId>alipay-sdk-java</artifactId>
    <version>4.38.10.ALL</version>
</dependency>

@Controller
@RequestMapping("/alipay")
public class AlipayDemo {
    private String serverUrl="https://openapi.alipaydev.com/gateway.do";
    private String appId="202300061726712"; //请换成你自己的
    private String privateKey="MIIEvgIBADsFOc..."; //请换成你自己的
    private String alipayPublicKey="MIIBIjANBgkqhki..."; //请换成你自己的

    //创建订单接口
    @ResponseBody
    @GetMapping("/create")
    public String create(){
        //创建连接
        AlipayClient alipayClient = new DefaultAlipayClient(serverUrl,appId,privateKey,"json", "UTF-8",alipayPublicKey,"RSA2");
        AlipayTradePagePayRequest request = new AlipayTradePagePayRequest();

        //订单信息
        JSONObject bizContent = new JSONObject();
        bizContent.put("out_trade_no", "202300012617623");
        bizContent.put("total_amount", 100.00);
        bizContent.put("subject", "付款");
        bizContent.put("product_code", "FAST_INSTANT_TRADE_PAY");

        request.setBizContent(bizContent.toString());

        AlipayTradePagePayResponse response = null;
        try {
            response = alipayClient.pageExecute(request);
        } catch (AlipayApiException e) {
            e.printStackTrace();
        }
        if(response.isSuccess()){
            //成功
            return  response.getBody();
        } else {
            //失败
           return  "调用失败";
        }
    }
}