<dependency>
      <groupId>com.alipay.sdk</groupId>
      <artifactId>alipay-sdk-java</artifactId>
      <version>3.0.0</version>
    </dependency>

public class AlipayConfig {

  // 應用ID,您的APPID，收款賬號既是您的APPID對應支付寶賬號,開發(fā)時使用沙箱提供的APPID，生產環(huán)境改成自己的APPID
  public static String APP_ID = "你的沙箱APPID";

  // 商戶私鑰，您的PKCS8格式RSA2私鑰
  public static String APP_PRIVATE_KEY = "你自己的私鑰";

  // 支付寶公鑰,查看地址：https://openhome.alipay.com/platform/keyManage.htm 對應APPID下的支付寶公鑰。
  public static String ALIPAY_PUBLIC_KEY = "你自己的支付寶公鑰，注意是支付寶公鑰，不是應用公鑰";

  // 服務器異步通知頁面路徑 需http://格式的完整路徑，不能加?id=123這類自定義參數(shù)，必須外網可以正常訪問
  public static String notify_url = "http://localhost:8080/alipay.trade.page.pay-JAVA-UTF-8/notify_url.jsp";

  // 頁面跳轉同步通知頁面路徑 需http://格式的完整路徑，不能加?id=123這類自定義參數(shù)，必須外網可以正常訪問(其實就是支付成功后返回的頁面)
  public static String return_url = "http://localhost:8080/alipay.trade.page.pay-JAVA-UTF-8/return_url.jsp";

  // 簽名方式
  public static String sign_type = "RSA2";

  // 字符編碼格式
  public static String CHARSET = "utf-8";

  // 支付寶網關，這是沙箱的網關
  public static String gatewayUrl = "https://openapi.alipaydev.com/gateway.do";

  // 支付寶網關
  public static String log_path = "C:\\";


//↑↑↑↑↑↑↑↑↑↑請在這里配置您的基本信息↑↑↑↑↑↑↑↑↑↑↑↑↑↑↑

  /**
   * 寫日志，方便測試（看網站需求，也可以改成把記錄存入數(shù)據(jù)庫）
   * @param sWord 要寫入日志里的文本內容
   */
  public static void logResult(String sWord) {
    FileWriter writer = null;
    try {
      writer = new FileWriter(log_path + "alipay_log_" + System.currentTimeMillis()+".txt");
      writer.write(sWord);
    } catch (Exception e) {
      e.printStackTrace();
    } finally {
      if (writer != null) {
        try {
          writer.close();
        } catch (IOException e) {
          e.printStackTrace();
        }
      }
    }
  }

@RestController
public class PayController {


  @RequestMapping("/pay")
  public void payController(HttpServletRequest request, HttpServletResponse response) throws IOException {
    //獲得初始化的AlipayClient
    AlipayClient alipayClient = new DefaultAlipayClient(AlipayConfig.gatewayUrl, AlipayConfig.APP_ID, AlipayConfig.APP_PRIVATE_KEY, "json", AlipayConfig.CHARSET, AlipayConfig.ALIPAY_PUBLIC_KEY, AlipayConfig.sign_type);

    //設置請求參數(shù)
    AlipayTradePagePayRequest alipayRequest = new AlipayTradePagePayRequest();
    alipayRequest.setReturnUrl(AlipayConfig.return_url);
    alipayRequest.setNotifyUrl(AlipayConfig.notify_url);

    //商戶訂單號，商戶網站訂單系統(tǒng)中唯一訂單號，必填
    String out_trade_no = new String(request.getParameter("WIDout_trade_no").getBytes("ISO-8859-1"),"UTF-8");
    //付款金額，必填
    String total_amount = new String(request.getParameter("WIDtotal_amount").getBytes("ISO-8859-1"),"UTF-8");
    //訂單名稱，必填
    String subject = new String(request.getParameter("WIDsubject").getBytes("ISO-8859-1"),"UTF-8");
    //商品描述，可空
    String body = new String(request.getParameter("WIDbody").getBytes("ISO-8859-1"),"UTF-8");

    alipayRequest.setBizContent("{\"out_trade_no\":\""+ out_trade_no +"\","
        + "\"total_amount\":\""+ total_amount +"\","
        + "\"subject\":\""+ subject +"\","
        + "\"body\":\""+ body +"\","
        + "\"product_code\":\"FAST_INSTANT_TRADE_PAY\"}");

    //若想給BizContent增加其他可選請求參數(shù)，以增加自定義超時時間參數(shù)timeout_express來舉例說明
    //alipayRequest.setBizContent("{\"out_trade_no\":\""+ out_trade_no +"\","
    //		+ "\"total_amount\":\""+ total_amount +"\","
    //		+ "\"subject\":\""+ subject +"\","
    //		+ "\"body\":\""+ body +"\","
    //		+ "\"timeout_express\":\"10m\","
    //		+ "\"product_code\":\"FAST_INSTANT_TRADE_PAY\"}");
    //請求參數(shù)可查閱【電腦網站支付的API文檔-alipay.trade.page.pay-請求參數(shù)】章節(jié)

    //請求
    String form="";
    try {
      form = alipayClient.pageExecute(alipayRequest).getBody(); //調用SDK生成表單
    } catch (AlipayApiException e) {
      e.printStackTrace();
    }
    response.setContentType("text/html;charset=" + AlipayConfig.CHARSET);
    response.getWriter().write(form);//直接將完整的表單html輸出到頁面
    response.getWriter().flush();
    response.getWriter().close();
  }

<!-- tomcat 依賴包 -->
    <dependency>
      <groupId>org.springframework.boot</groupId>
      <artifactId>spring-boot-starter-tomcat</artifactId>
    </dependency>
    <dependency>
      <groupId>org.apache.tomcat.embed</groupId>
      <artifactId>tomcat-embed-jasper</artifactId>
    </dependency>
    <!-- servlet 依賴包 -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
    </dependency>

spring.mvc.view.prefix=/WEB-INF/jsp/
spring.mvc.view.suffix=.jsp

<%@ page language="java" contentType="text/html; charset=UTF-8"
     pageEncoding="UTF-8"%>

<form action="/pay" method="post">
  訂單號：<input type="text" name="WIDout_trade_no" required><br/>
  訂單名稱：<input type="text" name="WIDsubject" required><br/>
  付款金額：<input type="text" name="WIDtotal_amount" required><br/>
  WIDbody：<input type="text" name="WIDbody"><br/>
  <input type="submit" value="下單"> <input type="reset" value="重置">
</form>

 @RequestMapping("/")
  public String toTest(){
    return "index";
  }