微信支付服务端代码开发

一、准备工作：
微信支付开发需要用到应用id（appid）、商户号（mch_id）和秘钥(key)、以及证书，这几个重要的参数需要从微信开发平台中去获得，在此不做赘述。
二、用户支付流程：用户在客户端中选择商品或者充值，提交订单，选择微信支付–>服务端收到用户支付订单，调用微信同意下单接口–>统一下单的接口返回appid_应用ID、partnerid_商户号、prepayid_预支付交易会话标识、package、noncestr_随机字符串和timestamp，而且都必须是小写–>客户端唤起微信支付–>服务端接收支付通知，处理业务逻辑–>服务端查询支付结果。
三、服务端代码编写：
在此我使用官方封装的SDK来进行开发，我的项目为maven项目
1、在pom.xml文件中添加如下配置：

<!-- 微信支付插件 -->
		<dependency>     
			<groupId>com.github.wxpay</groupId>     
			<artifactId>wxpay-sdk</artifactId>     
			<version>0.0.3</version> 
		</dependency>

2、编写配置文件，在调用官方封装的SDK的时候需要使用，代码如下：

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;

import com.github.wxpay.sdk.WXPayConfig;

public class WXConfigUtil implements WXPayConfig{
	private byte[] certData;
    public static final String APP_ID = "应用ID";
    public static final String KEY = "秘钥";
    public static final String MCH_ID = "商户ID";
    
    public WXConfigUtil() throws Exception {
        //String certPath = "D:/weixzhifu/1592702951_20200513_cert/apiclient_cert.pem";//从微信商户平台下载的安全证书存放的路径
        String certPath = "/usr/java/weixzhifu/1592702951_20200513_cert/apiclient_cert.pem";
        File file = new File(certPath);
        InputStream certStream = new FileInputStream(file);
        this.certData = new byte[(int) file.length()];
        certStream.read(this.certData);
        certStream.close();
    }

	@Override
	public String getAppID() {
		return APP_ID;
	}
	
	//parnerid，商户号
	@Override
	public String getMchID() {
		return MCH_ID;
	}

	@Override
	public String getKey() {
		return KEY;
	}

	@Override
	public InputStream getCertStream() {
		ByteArrayInputStream certBis = new ByteArrayInputStream(this.certData);
        return certBis;
	}

	@Override
	public int getHttpConnectTimeoutMs() {
		return 0;
	}

	@Override
	public int getHttpReadTimeoutMs() {
		return 0;
	}

}

3、服务端生成预支付订单和客户端支付后的异步回调
3.1、controller层代码：

@Autowired
private PaymentServiceI paymentService;
/**
	 *  微信支付
	 *  统一下单
     *  官方文档:https://pay.weixin.qq.com/wiki/doc/api/app/app.php?chapter=9_1
     * @param user_id
     * @param total_fee
     * @return
     * @throws Exception
     */
	@ApiOperation(value = "微信支付")
	@RequestMapping(value = "wxPay/", method = RequestMethod.POST, produces = "application/json")
	@ResponseBody
	@ApiImplicitParams({
		@ApiImplicitParam(paramType = "query", name = "phone", dataType = "String", required = true, value = "手机号"),
		@ApiImplicitParam(paramType = "query", name = "id", dataType = "String", required = true, value = "充值金额id"),
		@ApiImplicitParam(paramType = "query", name = "identification", dataType = "String", required = true, value = "是否优惠")})
    public Result<Object> wxPay(HttpServletRequest request,@RequestParam String phone,
    		@RequestParam String id,@RequestParam String identification) throws Exception {
		Result<Object> resu = new Result<Object>();
		try {
			String attach = "{\"phone\":\"" + phone + "\"}";
	        //请求预支付订单
	        Map<String, String> result = paymentServic