先创建Springboot项目

已上传至github库 https://github.com/gaoruiqiang2017/weixinpay.git

pom文件添加依赖

        <!--微信支付SDK-->
        <dependency>
            <groupId>com.github.wxpay</groupId>
            <artifactId>wxpay-sdk</artifactId>
            <version>0.0.3</version>
        </dependency>
        <dependency>
            <groupId>org.apache.httpcomponents</groupId>
            <artifactId>httpclient</artifactId>
            <version>4.5.5</version>
        </dependency>
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
            <version>1.2.47</version>
        </dependency>
        <dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>core</artifactId>
            <version>3.3.0</version>
        </dependency>
        <dependency>
            <groupId>com.google.zxing</groupId>
            <artifactId>javase</artifactId>
            <version>3.0.0</version>
        </dependency>
        <dependency>
            <groupId>commons-io</groupId>
            <artifactId>commons-io</artifactId>
            <version>2.6</version>
        </dependency>

utils工具类(可使用自己项目的)

public class HttpUtil {

    public static String doPost(String url, String requestXml) {
        CloseableHttpClient httpClient = null;
        CloseableHttpResponse httpResponse = null;
        //创建httpClient连接对象
        httpClient = HttpClients.createDefault();
        //创建post请求连接对象
        HttpPost httpPost = new HttpPost(url);
        //创建连接请求对象,并设置连接参数
        RequestConfig requestConfig = RequestConfig.custom()
                .setConnectTimeout(15000)   //连接服务区主机超时时间
                .setConnectionRequestTimeout(60000) //连接请求超时时间
                .setSocketTimeout(60000).build(); //设置读取响应数据超时时间
        //为httppost请求设置参数
        httpPost.setConfig(requestConfig);
        //将上传参数放到entity属性中
        httpPost.setEntity(new StringEntity(requestXml, "UTF-8"));
        //添加头信息
        httpPost.addHeader("Content-type", "text/xml");
        String result = "";
        try {
            //发送请求
            httpResponse = httpClient.execute(httpPost);
            //从相应对象中获取返回内容
            HttpEntity entity = httpResponse.getEntity();
            result = EntityUtils.toString(entity, "UTF-8");
        } catch (IOException e) {
            e.printStackTrace();
        }
        return result;

    }

Controller接口

@RestController
@RequestMapping("/weixinpay")
public class Weixinpay {
    
 

    @Value("${appid}")
    private String appid;  //公众账号id

    @Value("${mchid}")
    private String mchId;  //商户号

    @Value("${weixinKey}")
    private String weixinKey;  //密匙

    @Value("${unifiedorderUrl}")
    private String unifiedorderUrl; //统一下单接口

    /**
     * @param httpServletRequest
     * @param httpServletResponse
     * @param orderNo             订单号 (前面要创建自己的订单)
     * @param money               金额
     * @param body                商品内容
     */
    @RequestMapping("/pay")
    public void pay(HttpServletRequest httpServletRequest, HttpServletResponse
            httpServletResponse, String orderNo, String money, String body)
            throws Exception {
        try {
            HashMap<String, String> dataMap = new HashMap<>();
            dataMap.put("appid", appid); //公众账号ID
            dataMap.put("mch_id", mchId); //商户号
            dataMap.put("nonce_str", WXPayUtil.generateNonceStr()); //随机字符串，长度要求在32位以内。
            dataMap.put("body", body); //商品描述
            dataMap.put("out_trade_no", orderNo); //商品订单号
            dataMap.put("total_fee", money); //商品金
            dataMap.put("spbill_create_ip", InetAddress.getLocalHost().getHostAddress()); //客户端ip
            dataMap.put("notify_url", "www.baidu.com"); //通知地址(假设是百度)
            dataMap.put("trade_type", "NATIVE"); //交易类型
            dataMap.put("product_id", "1"); //trade_type=NATIVE时，此参数必传。商品ID，商户自行定义。
            //生成签名
            String signature = WXPayUtil.generateSignature(dataMap, weixinKey);
            dataMap.put("sign", signature);//签名
            //将类型为map的参数转换为xml
            String requestXml = WXPayUtil.mapToXml(dataMap);
            //发送参数,调用微信统一下单接口,返回xml
            String responseXml = HttpUtil.doPost(unifiedorderUrl, requestXml);
            Map<String, String> map = WXPayUtil.xmlToMap(responseXml);
            if (map.get("return_code").toString().equals("SUCCESS") && map.get("result_code")
                    .toString().equals("SUCCESS")) {
                String urlCode = (String) map.get("code_url"); //微信二维码短链接
                // 生成微信二维码(或者直接传给前端处理)
                Hashtable<EncodeHintType, String> hints = new Hashtable<EncodeHintType, String>();
                // 内容所使用编码
                hints.put(EncodeHintType.CHARACTER_SET, "utf-8");
                BitMatrix bitMatrix = new MultiFormatWriter().encode(urlCode, BarcodeFormat
                        .QR_CODE, 300, 300, hints);
                // 生成二维码
                MatrixToImageWriter.writeToFile(bitMatrix, "gif", new File("C:/downloads/二维码文件" +
                        ".gif"));
            } else {
            }
        } catch (Exception e) {

        }
    }
	
	//自定义回调接口
    @RequestMapping("/notifyUrl")
    public String notifyUrl(String unifiedorderUrl, String requestXml) {
        System.out.print("h");
        //扫码支付完成之后回调接口,修改订单状态
        return "回调成功";

    }
}