一. 前置条件

接入支付首先得需要有企业资质，并开通企业对公户
注册微信支付并进行对公户打款认证

二. 开始接入

1. 下载微信支付的AP证书

2. 服务端接入微信支付

2.1 引入相关maven配置

<dependency>
   <groupId>com.github.binarywang</groupId>
    <artifactId>weixin-java-miniapp</artifactId>
    <version>${wechat.sdk.version}</version>
</dependency>
<dependency>
    <groupId>com.github.binarywang</groupId>
    <artifactId>weixin-java-pay</artifactId>
    <version>${wechat.sdk.version}</version>
</dependency>

2.2 配置小程序相关信息

#微信支付配置
wx.pay.appId=xxxxxxxxxxxxxxxx
wx.pay.mchId=xxxxx
wx.pay.mchKey=xxxxxxxxxxxxxxxxx
wx.pay.keyPath=classpath:xxxxxxx.p12

2.3 相关配置类文件代码编写

WxPayConfiguration.java

package com.xxxxx;

import com.github.binarywang.wxpay.config.WxPayConfig;
import com.github.binarywang.wxpay.service.WxPayService;
import com.github.binarywang.wxpay.service.impl.WxPayServiceImpl;
import lombok.AllArgsConstructor;
import org.apache.commons.lang3.StringUtils;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;


@Configuration
@ConditionalOnClass(WxPayService.class)
@EnableConfigurationProperties(WxPayProperties.class)
@AllArgsConstructor
public class WxPayConfiguration {
  private WxPayProperties properties;

  @Bean
  @ConditionalOnMissingBean
  public WxPayService wxService() {
    WxPayConfig payConfig = new WxPayConfig();
    payConfig.setAppId(StringUtils.trimToNull(this.properties.getAppId()));
    payConfig.setMchId(StringUtils.trimToNull(this.properties.getMchId()));
    payConfig.setMchKey(StringUtils.trimToNull(this.properties.getMchKey()));
    payConfig.setKeyPath(StringUtils.trimToNull(this.properties.getKeyPath()));

    // 可以指定是否使用沙箱环境
    payConfig.setUseSandboxEnv(false);

    WxPayService wxPayService = new WxPayServiceImpl();
    wxPayService.setConfig(payConfig);
    return wxPayService;
  }

}

WxPayProperties.java

package com.xxxxx

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;

@Data
@ConfigurationProperties(prefix = "wx.pay")
public class WxPayProperties {
  /**
   * 设置微信公众号或者小程序等的appid
   */
  private String appId;

  /**
   * 微信支付商户号
   */
  private String mchId;

  /**
   * 微信支付商户密钥
   */
  private String mchKey;

  /**
   * apiclient_cert.p12文件的绝对路径，或者如果放在项目中，请以classpath:开头指定
   */
  private String keyPath;

  /**
   * 回调地址
   */
  private String notifyUrl;

}

2.4 下单退款API接入

package com.xxxxx

import com.alibaba.fastjson.JSON;
import com.github.binarywang.wxpay.bean.notify.WxPayOrderNotifyResult;
import com.github.binarywang.wxpay.bean.order.WxPayMpOrderResult;
import com.github.binarywang.wxpay.bean.request.WxPayRefundRequest;
import com.github.binarywang.wxpay.bean.request.WxPayUnifiedOrderRequest;
import com.github.binarywang.wxpay.bean.result.WxPayRefundResult;
import com.github.binarywang.wxpay.exception.WxPayException;
import com.github.binarywang.wxpay.service.WxPayService;
import com.xxxxx.CustomException;
import com.xxxxx.ResultCode;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

@Component
@Slf4j
public class WechatPayRepository {

    @Autowired
    private WxPayService wxPayService;

    /**
     * 统一下单 发起微信支付
     * @param request
     * @return
     */
    public WxPayMpOrderResult createOrder(WxPayUnifiedOrderRequest request) {
        try {
            return wxPayService.createOrder(request);
        } catch (WxPayException e) {
            log.error("微信发起支付失败: {}", e);
            throw new CustomException(ResultCode.WECHAT_PAY_CREATE_ORDER_ERROR);
        }
    }

    /**
     * 解析支付结果通知
     * @param xmlData
     * @return
     */
    public WxPayOrderNotifyResult parseOrderNotifyResult(String xmlData) {
        try {
            return wxPayService.parseOrderNotifyResult(xmlData);
        } catch (WxPayException e) {
            log.error("微信支付回调解析失败: {}", e);
            throw new CustomException(ResultCode.WECHAT_PAY_PARSE_ERROR);
        }
    }



    /**
     * 退款
     * @param request
     * @return
     */
    public WxPayRefundResult refund(WxPayRefundRequest request) {
        try {
            log.info("微信发起退款: {}", JSON.toJSONString(request));
            return wxPayService.refund(request);
        } catch (WxPayException e) {
            if("INVALID_REQUEST".equals(e.getErrCode()) && "订单已全额退款".equals(e.getErrCodeDes())) {
                return null;
            }
            log.error("微信发起退款失败: {}", e);
            throw new CustomException(ResultCode.WECHAT_PAY_REFUND_ERROR);
        }
    }
}

3. 小程序端接入支付

wx.requestPayment({
 timeStamp: timeStamp,
 nonceStr: nonceStr,
 package: packageValue,
 signType: signType,
 paySign: paySign,
 success(res) {
   wx.reLaunch({
     url: '/xxx/xxx'
   });
 },
 fail(res) { }
})