Android微信支付SDK开发

准备工作

开发平台及SDK下载

微信开放平台申请APP：https://open.weixin.qq.com

微信支付SDK及Demo下载：http://pay.weixin.qq.com/wiki/doc/api/app.php?chapter=11_1

创建应用

创建移动应用获取AppID和AppSecret

要获取支付功能还需要开发者资质认证，300RMB/年的费用，貌似是开放平台中唯一要收费的

AndroidMainfest文件修改

配置权限

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"/>
<uses-permission android:name="android.permission.ACCESS_WIFI_STATE"/>
<uses-permission android:name="android.permission.READ_PHONE_STATE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

业务流程

商户系统和微信支付系统主要交互说明：

步骤1：用户在商户APP中选择商品，提交订单，选择微信支付。

步骤2：商户后台收到用户支付单，调用微信支付统一下单接口。参见【统一下单API】。

步骤3：统一下单接口返回正常的prepay_id，再按签名规范重新生成签名后，将数据传输给APP。参与签名的字段名为appId，partnerId，prepayId，nonceStr，timeStamp，package。注意：package的值格式为Sign=WXPay

步骤4：商户APP调起微信支付。api参见本章节【App端开发步骤说明】

步骤5：商户后台接收支付通知。api参见【支付结果通知API】

步骤6：商户后台查询支付结果。api参见【查询订单API】

开发

注册应用

final IWXAPI msgApi = WXAPIFactory.createWXAPI(this, null);
msgApi.registerApp(Constants.APP_ID);

调用支付统一下单接口，并返回PrepayID

private class GetPrepayIdTask extends AsyncTask<Void, Void, Map<String,String>> {

    private ProgressDialog dialog;

    @Override
    protected void onPreExecute() {
        dialog = ProgressDialog.show(PayActivity.this, getString(R.string.app_tip), getString(R.string.getting_prepayid));
    }

    @Override
    protected void onPostExecute(Map<String, String> result) {
        if (dialog != null) {
            dialog.dismiss();
        }
        sb.append("prepay_id\n" + result.get("prepay_id") + "\n\n");
        show.setText(sb.toString());
        unifiedorderResult = result;
    }

    @Override
    protected void onCancelled() {
        super.onCancelled();
    }

    @Override
    protected Map<String,String>  doInBackground(Void... params) {
        String url = String.format("https://api.mch.weixin.qq.com/pay/unifiedorder");
        String entity = genProductArgs();
        Log.e("orion", entity);
        byte[] buf = Util.httpPost(url, entity);
        String content = new String(buf);
        Log.e("orion", content);
        Map<String,String> xml = decodeXml(content);
        return xml;
    }
}

设置统一下单参数：

private String genProductArgs() {
    StringBuffer xml = new StringBuffer();
    try {
        String  nonceStr = genNonceStr();
        xml.append("</xml>");
       List<NameValuePair> packageParams = new LinkedList<NameValuePair>();
        packageParams.add(new BasicNameValuePair("appid", Constants.APP_ID));
        packageParams.add(new BasicNameValuePair("body", "APP pay test"));
        packageParams.add(new BasicNameValuePair("mch_id", Constants.MCH_ID));
        packageParams.add(new BasicNameValuePair("nonce_str", nonceStr));
        packageParams.add(new BasicNameValuePair("notify_url", "http://www.yezhou.cc/callback/notify.php"));
        packageParams.add(new BasicNameValuePair("out_trade_no", genOutTradNo()));
        packageParams.add(new BasicNameValuePair("spbill_create_ip", "127.0.0.1"));
        packageParams.add(new BasicNameValuePair("total_fee", "1"));
        packageParams.add(new BasicNameValuePair("trade_type", "APP"));

        String sign = genPackageSign(packageParams);
        packageParams.add(new BasicNameValuePair("sign", sign));
       String xmlstring =toXml(packageParams);
        return xmlstring;
    } catch (Exception e) {
        Log.e(TAG, "genProductArgs fail, ex = " + e.getMessage());
        return null;
    }
}

设置PayReq请求的参数，并发送支付请求

//设置PayReq请求的参数
private void genPayReq() {
    req.appId = Constants.APP_ID;
    req.partnerId = Constants.MCH_ID;
    req.prepayId = unifiedorderResult.get("prepay_id");
    req.packageValue = "prepay_id=" + unifiedorderResult.get("prepay_id");
    req.nonceStr = genNonceStr();
    req.timeStamp = String.valueOf(genTimeStamp());

    List<NameValuePair> signParams = new LinkedList<NameValuePair>();
    signParams.add(new BasicNameValuePair("appid", req.appId));
    signParams.add(new BasicNameValuePair("noncestr", req.nonceStr));
    signParams.add(new BasicNameValuePair("package", req.packageValue));
    signParams.add(new BasicNameValuePair("partnerid", req.partnerId));
    signParams.add(new BasicNameValuePair("prepayid", req.prepayId));
    signParams.add(new BasicNameValuePair("timestamp", req.timeStamp));

    req.sign = genAppSign(signParams);
    sb.append("sign\n" + req.sign + "\n\n");
    show.setText(sb.toString());
    Log.e("orion", signParams.toString()); 
}

//发送请求
msgApi.sendReq(req);

处理结果回调

实现微信API的IWXAPIEventHandler接口

api.handleIntent(getIntent(), new IWXAPIEventHandler);

在IWXAPIEventHandler的onResp(BaseResp resp)中处理请求回调

@Override
public void onResp(BaseResp resp) {
    Log.d(TAG, "onPayFinish, errCode = " + resp.errCode);

    if (resp.getType() == ConstantsAPI.COMMAND_PAY_BY_WX) {
        //处理PayReq的回调
        AlertDialog.Builder builder = new AlertDialog.Builder(this);
        builder.setTitle(R.string.app_tip);
        builder.setMessage(getString(R.string.pay_result_callback_msg, resp.errStr + ";code=" + String.valueOf(resp.errCode)));
        builder.show();
    }
}