这两天在项目里面接入了微信支付，刚开始在项目里面引入了官方提供的sdk，这是下载地址https://pay.weixin.qq.com/wiki/doc/api/app/app.php?chapter=11_1，填入了在微信开发平台申请的，应用的APP_ID APP_SECRET已经PARTNER_ID，自己生成一个订单，发现可以跳转到微信进行支付，但是和后台调试的时候，拿到后台给我的订单信息，进入微信，发现只有一个确定按钮，
当时在网上搜了不少文章，但是没有符合自己情况的，和后台一起按照步奏调试了好几天，好在问题最后解决了，分享一下给遇到同样问题的同学看看，也避免以后自己踩到同样的坑，下面，我尽可能用通俗的语言，说一下我遇到问题的原因和解决方法。
3，首先看一下在客户端，选择一个要买的商品以后，点击去微信支付，在没有进入微信前经历了什么
3 .1 下单 这里面呢需要提供三个参数，orderid是要买商品的id，ordertitle是在跳转到微信支付里面，展示给用户的订单标题，orderprice是商品的价钱了，iOS里面对应下订单的方法如下
- ( NSMutableDictionary *)sendPay_demo:(NSString *)orderid title:(NSString *)ordertitle price:(NSString *)orderprice
{
//订单标题，展示给用户
NSString *order_name = ordertitle;
//订单金额,单位（分）
NSString *order_price = orderprice;//1分钱测试
//================================
//预付单参数订单设置
//================================
srand( (unsigned)time(0) );
NSString *noncestr = [NSString stringWithFormat:@"%d", rand()];
NSMutableDictionary *packageParams = [NSMutableDictionary dictionary];
NSString *ii=@"079d9a74b95f41c58e636e344109ee1f";
[packageParams setObject: appid forKey:@"appid"]; //开放平台appid
[packageParams setObject: mchid forKey:@"mch_id"]; //商户号
[packageParams setObject: @"APP-001" forKey:@"device_info"]; //支付设备号或门店号
NSLog(@"第一次noncestr %@",noncestr);
[packageParams setObject: noncestr forKey:@"nonce_str"]; //随机串
[packageParams setObject: @"APP" forKey:@"trade_type"]; //支付类型，固定为APP
[packageParams setObject: order_name forKey:@"body"]; //订单描述，展示给用户
[packageParams setObject: NOTIFY_URL forKey:@"notify_url"]; //支付结果异步通知
[packageParams setObject: orderid forKey:@"out_trade_no"];//商户订单号
[packageParams setObject: @"196.168.1.1" forKey:@"spbill_create_ip"];//发器支付的机器ip
[packageParams setObject: order_price forKey:@"total_fee"]; //订单金额，单位为分
//获取prepayId（预支付交易会话标识）
NSString *prePayid;
prePayid = [self sendPrepay:packageParams];
NSLog(@"获取prepayId %@",prePayid);
if ( prePayid != nil) {
//获取到prepayid后进行第二次签名
NSString *package, *time_stamp, *nonce_str;
//设置支付参数
time_t now;
time(&now);
time_stamp = [NSString stringWithFormat:@"%ld", now];
nonce_str = [WXUtil md5:time_stamp];
//重新按提交格式组包，微信客户端暂只支持package=Sign=WXPay格式，须考虑升级后支持携带package具体参数的情况
//package = [NSString stringWithFormat:@"Sign=%@",package];
package = @"Sign=WXPay";
//第二次签名参数列表
NSMutableDictionary *signParams = [NSMutableDictionary dictionary];
[signParams setObject: appid forKey:@"appid"];
NSLog(@"第二次noncestr %@ %@",nonce_str,time_stamp);
[signParams setObject: nonce_str forKey:@"noncestr"];
[signParams setObject: package forKey:@"package"];
[signParams setObject: mchid forKey:@"partnerid"];
[signParams setObject: time_stamp forKey:@"timestamp"];
[signParams setObject: prePayid forKey:@"prepayid"];
//[signParams setObject: @"MD5" forKey:@"signType"];
//生成签名
NSString *sign = [self createMd5Sign:signParams];
//添加签名
[signParams setObject: sign forKey:@"sign"];
[debugInfo appendFormat:@"第二步签名成功，sign＝%@\n",sign];
//返回参数列表
return signParams;
}else{
[debugInfo appendFormat:@"获取prepayid失败！\n"];
}
return nil;
}
3.2这里面非常重要的一步是提交预支付获取prepayid，我们的错误就出在这里，获取prepayid的方法如下
//提交预支付
-(NSString *)sendPrepay:(NSMutableDictionary *)prePayParams
{
NSString *prepayid = nil;
NSLog(@"提交预支付发送的数据%@",prePayParams);
//获取提交支付
NSString *send = [self genPackage:prePayParams];
NSLog(@"获取提交支付 send %@",send);
//输出Debug Info
[debugInfo appendFormat:@"API链接:%@\n", payUrl];
[debugInfo appendFormat:@"发送的xml:%@\n", send];
//发送请求post xml数据
NSData *res = [WXUtil httpSend:payUrl method:@"POST" data:send];
//输出Debug Info
[debugInfo appendFormat:@"服务器返回：\n%@\n\n",[[NSString alloc] initWithData:res encoding:NSUTF8StringEncoding]];
XMLHelper *xml = [[XMLHelper alloc] init];
//开始解析
[xml startParse:res];
NSMutableDictionary *resParams = [xml getDict];
NSString *return_code = [resParams objectForKey:@"return_code"];
NSString *result_code = [resParams objectForKey:@"result_code"];
if ( [return_code isEqualToString:@"SUCCESS"] )
{
//生成返回数据的签名
NSString *sign = [self createMd5Sign:resParams ];
NSString *send_sign =[resParams objectForKey:@"sign"] ;
//验证签名正确性
if( [sign isEqualToString:send_sign]){
if( [result_code isEqualToString:@"SUCCESS"]) {
//验证业务处理状态
prepayid = [resParams objectForKey:@"prepay_id"];
return_code = 0;
[debugInfo appendFormat:@"获取预支付交易标示成功！\n"];
}
}else{
last_errcode = 1;
[debugInfo appendFormat:@"gen_sign=%@\n _sign=%@\n",sign,send_sign];
[debugInfo appendFormat:@"服务器返回签名验证错误！！！\n"];
}
}else{
last_errcode = 2;
[debugInfo appendFormat:@"接口返回错误！！！\n"];
}
return prepayid;
}
3.3 这个方法进行了第一次MD5的加密，
//获取package带参数的签名包
-(NSString *)genPackage:(NSMutableDictionary*)packageParams
{
NSString *sign;
NSMutableString *reqPars=[NSMutableString string];
//生成签名
sign = [self createMd5Sign:packageParams];
//生成xml的package
NSArray *keys = [packageParams allKeys];
[reqPars appendString:@"<xml>\n"];
for (NSString *categoryId in keys) {
[reqPars appendFormat:@"<%@>%@</%@>\n", categoryId, [packageParams objectForKey:categoryId],categoryId];
}
[reqPars appendFormat:@"<sign>%@</sign>\n</xml>", sign];
return [NSString stringWithString:reqPars];
}
就是通过上面的这个方法，获得了向微信发送的生成订单xml的内容，我们后台刚开始的错误是生成sign签名的时候，他没有找到系统提供给后台的生成签名的方法，就自己写了一个方法进行签名，然后他把所有的参数，包括key进行ASCII码从小到大排序，事实上应该把除key以外的参数进行排序，且参数名要区分大小写，排序后，在得到的字符串后面在追加key.
iOS里面签名的方法是下面这个
-(NSString*) createMd5Sign:(NSMutableDictionary*)dict
{
NSMutableString *contentString =[NSMutableString string];
NSArray *keys = [dict allKeys];
//按字母顺序排序
NSArray *sortedArray = [keys sortedArrayUsingComparator:^NSComparisonResult(id obj1, id obj2) {
return [obj1 compare:obj2 options:NSNumericSearch];
}];
//拼接字符串
for (NSString *categoryId in sortedArray) {
if ( ![[dict objectForKey:categoryId] isEqualToString:@""]
&& ![categoryId isEqualToString:@"sign"]
&& ![categoryId isEqualToString:@"key"]
)
{
[contentString appendFormat:@"%@=%@&", categoryId, [dict objectForKey:categoryId]];
}
}
//添加key字段
spkey=PARTNER_ID;
[contentString appendFormat:@"key=%@", spkey];
NSLog(@"数据排序前 %@ 数据排序后sortedArray %@ 先把参数排序后追加一个key后得到 %@",keys,sortedArray,contentString);
NSLog(@"添加key字段 %@",spkey);
//得到MD5 sign签名
NSString *md5Sign =[WXUtil md5:contentString];
//输出Debug Info
[debugInfo appendFormat:@"MD5签名字符串：\n%@\n\n",contentString];
return md5Sign;
}
3.4在获得prepayid以后，还要在进行第二次签名 ios里面对应的方法是这个
if ( prePayid != nil) {
//获取到prepayid后进行第二次签名
NSString *package, *time_stamp, *nonce_str;
//设置支付参数
time_t now;
time(&now);
time_stamp = [NSString stringWithFormat:@"%ld", now];
nonce_str = [WXUtil md5:time_stamp];
//重新按提交格式组包，微信客户端暂只支持package=Sign=WXPay格式，须考虑升级后支持携带package具体参数的情况
//package = [NSString stringWithFormat:@"Sign=%@",package];
package = @"Sign=WXPay";
//第二次签名参数列表
NSMutableDictionary *signParams = [NSMutableDictionary dictionary];
[signParams setObject: appid forKey:@"appid"];
NSLog(@"第二次noncestr %@ %@",nonce_str,time_stamp);
[signParams setObject: nonce_str forKey:@"noncestr"];
[signParams setObject: package forKey:@"package"];
[signParams setObject: mchid forKey:@"partnerid"];
[signParams setObject: time_stamp forKey:@"timestamp"];
[signParams setObject: prePayid forKey:@"prepayid"];
//[signParams setObject: @"MD5" forKey:@"signType"];
//生成签名
NSString *sign = [self createMd5Sign:signParams];
//添加签名
[signParams setObject: sign forKey:@"sign"];
[debugInfo appendFormat:@"第二步签名成功，sign＝%@\n",sign];
//返回参数列表
return signParams;
}
3.5 这时候就生成了跳转到微信所需要的signParams ，然后在iOS客户端里面调用下面的方法就可以发起支付了
NSMutableString *stamp = [dict objectForKey:@"timestamp"];
//调起微信支付
PayReq* req = [[PayReq alloc] init];
req.openID = [dict objectForKey:@"appid"];
req.partnerId = [dict objectForKey:@"partnerid"];
req.prepayId = [dict objectForKey:@"prepayid"];
req.nonceStr = [dict objectForKey:@"noncestr"];
req.timeStamp = stamp.intValue;
req.package = [dict objectForKey:@"package"];
req.sign = [dict objectForKey:@"sign"];
BOOL status = [WXApi sendReq:req];
总结一下，我开始遇到跳转微信只有一个确定按钮，就是因为服务器那边在进行签名的时候，出错了，微信支付流程就服务器在下订单前要进行一次签名，拿到prepayid以后要再进行一次签名，不知道大家遇到的问题是否和我一样，如果不一样，你刚好也解决了，欢迎补充。
