Java 支付宝当面付生成二维码支付实现

参考官方APIalipay.trade.precreate(统一收单线下交易预创建)

1. maven依赖：

        <!-- 支付宝支付sdk -->
        <dependency>
            <groupId>com.alipay.sdk</groupId>
            <artifactId>alipay-sdk-java</artifactId>
            <version>4.9.124.ALL</version>
        </dependency>

        <!-- 二维码工具 -->
        <dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>core</artifactId>
            <version>3.3.3</version>
        </dependency>
        <dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>javase</artifactId>
            <version>3.3.3</version>
        </dependency>

2. 准备工作：

AlipayConfig 配置类在第一篇关于支付宝支付文章里有写到：
Java 支付宝手机网站支付下单 支付回调 及订单查询实现
这里直接用了
file.qrCode是在配置文件里写到的二维码图片本地存储位置，

需要在项目里配置虚拟路径，参考SpringBoot文件虚拟路径配置，
以及图片开放访问，有权限限制的项目需要这一步，项目不同开放的方式也不同，举例：

如果是分布式项目的话，集成MinIO来存储图片会更好，参考
Java MinIO文件上传返回访问路径及访问配置

3. 代码：

QrCodeUtil

import com.google.zxing.*;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.QRCodeWriter;
import com.google.zxing.qrcode.decoder.ErrorCorrectionLevel;

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.*;
import java.util.Hashtable;

public class QrCodeUtil {
    /**
     * 生成包含字符串信息的二维码图片
     * @param outputStream 文件输出流路径
     * @param content 二维码携带信息
     */
    public static boolean createQrCode(OutputStream outputStream, String content) throws WriterException, IOException{
        //设置二维码纠错级别ＭＡＰ
        Hashtable<EncodeHintType, ErrorCorrectionLevel> hintMap = new Hashtable<EncodeHintType, ErrorCorrectionLevel>();
        hintMap.put(EncodeHintType.ERROR_CORRECTION, ErrorCorrectionLevel.L);  // 矫错级别
        QRCodeWriter qrCodeWriter = new QRCodeWriter();
        //创建比特矩阵(位矩阵)的QR码编码的字符串
        BitMatrix byteMatrix = qrCodeWriter.encode(content, BarcodeFormat.QR_CODE, 900, 900, hintMap);
        // 使BufferedImage勾画QRCode  (matrixWidth 是行二维码像素点)
        int matrixWidth = byteMatrix.getWidth();
        BufferedImage image = new BufferedImage(matrixWidth-200, matrixWidth-200, BufferedImage.TYPE_INT_RGB);
        image.createGraphics();
        Graphics2D graphics = (Graphics2D) image.getGraphics();
        graphics.setColor(Color.WHITE);
        graphics.fillRect(0, 0, matrixWidth, matrixWidth);
        // 使用比特矩阵画并保存图像
        graphics.setColor(Color.BLACK);
        for (int i = 0; i < matrixWidth; i++){
            for (int j = 0; j < matrixWidth; j++){
                if (byteMatrix.get(i, j)){
                    graphics.fillRect(i-100, j-100, 1, 1);
                }
            }
        }
        return ImageIO.write(image, "JPEG", outputStream);
    }
}

controller

    @Value("${file.qrCode}")
    private String qrCode;

    @PreAuthorize("@el.check('anonymous')")	// 匿名访问
    @PostMapping("/alipayPrecreate")
    public ResponseEntity alipayPrecreate(@RequestBody Map params) throws Exception {
		// 创建订单并返回订单id
        ShopOrderDTO shopOrderDTO = createOrder(params);

		// 支付请求参数准备 
        AlipayConfig alipayConfig = new AlipayConfig(shopDeviceService);

        AlipayClient alipayClient = new DefaultAlipayClient(alipayConfig.getUrl(), alipayConfig.getAppId(),
                alipayConfig.getRSAPrivateKey(), alipayConfig.getFormat(), alipayConfig.getCharset(),
                alipayConfig.getAliPayPublicKey(), alipayConfig.getSignType());
        AlipayTradePrecreateRequest req = new AlipayTradePrecreateRequest();

        AlipayTradePrecreateModel model=new AlipayTradePrecreateModel();
        model.setOutTradeNo(shopOrderDTO.getId().toString());
        model.setSubject(alipayConfig.getSubject());
        String amount = String.valueOf(shopOrderDTO.getAmount().floatValue() / 100);
        model.setTotalAmount(amount);
        req.setBizModel(model);
        req.setNotifyUrl(alipayConfig.getNotifyUrl());

        logger.info("发起AliPay下单请求");
        AlipayTradePrecreateResponse execute = alipayClient.execute(req);

        String result = execute.getBody();
        JSONObject res = JSON.parseObject(result);
        Map response = (Map) res.get("alipay_trade_precreate_response");
        if (response.get("code").toString().equals("10000") && response.get("qr_code") != null) {
        
        	// 将返回的二维码存储至本地
            String path = qrCode + shopOrderDTO.getId() + "AliPay.jpg";
            String httpPath = "/qrCode/" + shopOrderDTO.getId() + "AliPay.jpg";
            File file = new File(path);
            if (!file.getParentFile().exists()) {
                file.getParentFile().mkdirs();
            }
            QrCodeUtil.createQrCode(new FileOutputStream(file), response.get("qr_code").toString());
            
            // 将图片可访问的url返回给前端
            response.put("qrcode", httpPath);
            
            return new ResponseEntity<>(response, HttpStatus.OK);
        }
        return new ResponseEntity<>(response, HttpStatus.OK);

    }