微信APP支付开发的流程跟前面所讲的微信公众号支付开发、微信扫码开发基本一致，但是所需要的appid和mch_id不一样，这个是比较坑的地方，而且微信的开发文档并没有明显说明这一点，导致很多开发者在这一步掉坑。下面会在开发过程中特殊所遇到的坑与解决方法。
一、前期准备工作
1、申请一个微信开发者账号
2、创建APP应用
3、申请开通该APP应用支付功能（会开通一个新的微信商户后台，跟公众号的商户后台不是同一个，注意：商户号mch_id也不是同一个）
4、备案的域名+服务器（这个是必备的）
二、微信公众号支付开发流程
1、根据微信支付文档封装支付参数，调用微信支付统一下单接口向微信服务器发起请求，返回微信预支付交易会话标识。微信文档链接
2、封装APP端需要的支付接口参数
3、APP应用接收支付参数，调起微信APP支付。
三、代码开发流程
前面粗略讲解了微信APP支付的开发流程，理解起来应该是相对简单。下面是示例代码(只是测试代码，不要用于生产环境)：
1、调用微信统一下单接口，获取微信预支付交易会话标识。
调用统一下单接口类 wxpay.class.php1
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194<?php
/**
* 微信支付
*/
class WxPay
{
private $apiUrl = 'https://api.mch.weixin.qq.com/pay/unifiedorder';
private $key;
private $mch_id;
private $appid;
private $openid;
private $nonce_str;
private $body;
private $out_trade_no;
private $total_fee;
private $spbill_create_ip;
private $notify_url;
private $trade_type;
function __construct($attributes)
{
$this->key = $attributes['key'];
$this->mch_id = $attributes['mch_id'];
$this->appid = $attributes['appid'];
$this->openid = $attributes['openid'];
$this->body = $attributes['body'];
$this->total_fee = $attributes['total_fee'];
$this->trade_type = $attributes['trade_type'];
$this->notify_url = $attributes['notify_url'];
}
//发送post请求
function http_post($url, $param) {
$header [] = "content-type: application/json; charset=UTF-8";
$ch = curl_init ();
curl_setopt ( $ch, CURLOPT_URL, $url );
curl_setopt ( $ch, CURLOPT_CUSTOMREQUEST, "POST" );
curl_setopt ( $ch, CURLOPT_SSL_VERIFYPEER, FALSE );
curl_setopt ( $ch, CURLOPT_SSL_VERIFYHOST, FALSE );
curl_setopt ( $ch, CURLOPT_HTTPHEADER, $header );
curl_setopt ( $ch, CURLOPT_USERAGENT, 'Mozilla/4.0 (compatible; MSIE 5.01; Windows NT 5.0)' );
curl_setopt ( $ch, CURLOPT_FOLLOWLOCATION, 1 );
curl_setopt ( $ch, CURLOPT_AUTOREFERER, 1 );
curl_setopt ( $ch, CURLOPT_POSTFIELDS, $param );
curl_setopt ( $ch, CURLOPT_RETURNTRANSFER, true );
$res = curl_exec ( $ch );
curl_close ( $ch );
//$res = json_decode ( $res, true );
return $res;
}
//数组转换为xml格式
function arrayToXml($arr)
{
$xml = "<xml>";
foreach ($arr as $key=>$val)
{
if (is_numeric($val)){
$xml.="<".$key.">".$val."</".$key.">";
}else{
$xml.="<".$key."><![CDATA[".$val."]]></".$key.">";
}
}
$xml.="</xml>";
return $xml;
}
//将XML转为数组
function xmlToArray($xml)
{
//禁止引用外部xml实体
libxml_disable_entity_loader(true);
$values = json_decode(json_encode(simplexml_load_string($xml, 'SimpleXMLElement', LIBXML_NOCDATA)), true);
return $values;
}
//支付参数签名
function paySign($array, $key){
ksort($array);
$str = '';
foreach($array as $k => $value){
$str .= $k.'='.$value.'&';
}
$str .= "key=".$key;
$str = strtoupper(md5($str));
return $str;
}
//生成随机字符串
function get_rand_char($length = 6, $type = 1) {
$str1 = "ABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789abcdefghijklmnopqrstuvwxyz";
$str2 = "0123456789";
$strLength1 = 61;
$strLength2 = 9;
$res = '';
if($type == 1){
for($i = 0; $i < $length; $i ++) {
$res .= $str1 [rand ( 0, $strLength1 )];
}
}else{
for($i = 0; $i < $length; $i ++) {
$res .= $str2 [rand ( 0, $strLength2 )];
}
}
return $res;
}
//获取IP
function get_client_ip() {
$ip = $_SERVER['REMOTE_ADDR'];
if (isset($_SERVER['HTTP_CLIENT_IP']) && preg_match('/^([0-9]{1,3}\.){3}[0-9]{1,3}$/', $_SERVER['HTTP_CLIENT_IP'])) {
$ip = $_SERVER['HTTP_CLIENT_IP'];
} elseif(isset($_SERVER['HTTP_X_FORWARDED_FOR']) AND preg_match_all('#\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}#s', $_SERVER['HTTP_X_FORWARDED_FOR'], $matches)) {
foreach ($matches[0] AS $xip) {
if (!preg_match('#^(10|172\.16|192\.168)\.#', $xip)) {
$ip = $xip;
break;
}
}
}
return $ip == '::1' ? '127.0.0.1' : $ip;
}
function prepare(){
$payConfig = [
'mch_id' => $this->mch_id,
'appid' => $this->appid,
'openid' => $this->openid,
'nonce_str' => $this->get_rand_char(32,2),
'body' => $this->body,
'out_trade_no' => date('YmdHis').$this->get_rand_char(6,1),
'total_fee' => $this->total_fee,
'spbill_create_ip' => $this->get_client_ip(),
'notify_url' => $this->notify_url,
'trade_type' => $this->trade_type,
];
$sign = $this->paySign($payConfig, $this->key);
$payConfig['sign'] = $sign;
$payXML = $this->arrayToXml($payConfig);
$result = $this->http_post($this->apiUrl, $payXML);
return $this->xmlToArray($result);
}
function qr_prepare(){
$payConfig = [
'mch_id' => $this->mch_id,
'appid' => $this->appid,
'nonce_str' => $this->get_rand_char(32,2),
'body' => $this->body,
'out_trade_no' => date('YmdHis').$this->get_rand_char(6,1),
'total_fee' => $this->total_fee,
'spbill_create_ip' => $this->get_client_ip(),
'notify_url' => $this->notify_url,
'trade_type' => $this->trade_type,
];
$sign = $this->paySign($payConfig, $this->key);
$payConfig['sign'] = $sign;
$payXML = $this->arrayToXml($payConfig);
$result = $this->http_post($this->apiUrl, $payXML);
return $this->xmlToArray($result);
}
function configForPayment($prepayId){
$jsPayConfig = [
'appId' => $this->appid,
'timeStamp' => strval(time()),
'nonceStr' => $this->get_rand_char(32,2),
'package' => "prepay_id=$prepayId",
'signType' => 'MD5',
];
$jsPayConfig['paySign'] = $this->paySign($jsPayConfig, $this->key);
return json_encode($jsPayConfig);
}
function configForApp($prepayId){
$PayConfig = [
'appid' => $this->appid,
'partnerid' => $this->mch_id,
'prepayid' => $prepayId,
'package' => 'Sign=WXPay',
'nonceStr' => $this->get_rand_char(32,2),
'timestamp' => strval(time()),
];
$PayConfig['sign'] = $this->paySign($PayConfig, $this->key);
return json_encode($PayConfig);
}
}
测试代码 test.php1
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36<?php
//引入微信支付类
include 'wxpay.class.php';
//APPID(微信开放平台审核通过的应用APPID)
$appid = 'APPID';
//商户号(微信开放平台对应的商户平台的商户号)
$mch_id = 'MCH_ID';
//API KEY
$key = 'KEY';
//支付回调地址
$notify_url = 'http://whatcode.cn/notify.php';
//商品描述
$body = '微信测试';
//商品价格
$total_fee = '100';
//微信支付类型(注意支付类型不要搞错，这里用APP)
$trade_type = 'APP';
//支付配置参数
$attributes = [
'mch_id' => $mch_id,
'key' => $key,
'appid' => $appid,
'body' => $body,
'total_fee' => $total_fee,
'notify_url' => $notify_url,
'trade_type' => $trade_type,
];
$wxpay = new WxPay($attributes);
$result = $wxpay->qr_prepare();
//打印输出$result
print_r($result);
//如果提示“商户未开通此接口权限”，有两个可能：1、商户号mch_id填错了,appid填错了 2、该APP应用没用开通微信支付，第一种可能性最大
?>
2、封装APP端需要的支付接口参数
测试代码：1
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36//引入微信支付类
include 'wxpay.class.php';
//APPID(微信开放平台审核通过的应用APPID)
$appid = 'APPID';
//商户号(微信开放平台对应的商户平台的商户号)
$mch_id = 'MCH_ID';
//API KEY
$key = 'KEY';
//支付回调地址
$notify_url = 'http://whatcode.cn/notify.php';
//商品描述
$body = '微信测试';
//商品价格
$total_fee = '100';
//微信支付类型(注意支付类型不要搞错，这里用APP)
$trade_type = 'APP';
//支付配置参数
$attributes = [
'mch_id' => $mch_id,
'key' => $key,
'appid' => $appid,
'body' => $body,
'total_fee' => $total_fee,
'notify_url' => $notify_url,
'trade_type' => $trade_type,
];
$wxpay = new WxPay($attributes);
$result = $wxpay->qr_prepare();
if ($result['return_code'] == 'SUCCESS' && $result['result_code'] == 'SUCCESS'){
$appPayConfig = $wxpay->configForApp($result['prepay_id']);
//APP端需要的支付参数（安卓或者IOS）
print_r($appPayConfig)
}
如果到这一步都没问题，那么剩下的就是安卓端或者IOS端的事情了。
四、总结
微信APP支付开发的流程跟前面所讲的微信公众号支付开发、微信扫码开发基本一致，但是所需要的appid和mch_id不一样，这里很容易搞错，加上微信的开发文档没有特殊说明，加上商户后台众多，很容易就掉坑。
