Java实现JsApi方式的微信支付

要使用JsApi进行微信支付，首先要从微信获得一个prepay_id，然后通过调用微信的jsapi完成支付，JS API的返回结果get_brand_wcpay_request:ok仅在用户成功完成支付时返回。由于前端交互复杂，get_brand_wcpay_request:cancel或者get_brand_wcpay_request:fail可以统一处理为用户遇到错误或者主动放弃，不必细化区分。
示例代码如下：

function onBridgeReady(){
   WeixinJSBridge.invoke(
       'getBrandWCPayRequest', {
           "appId" : "wx2421b1c4370ec43b",     //公众号名称，由商户传入     
           "timeStamp":" 1395712654",         //时间戳，自1970年以来的秒数     
           "nonceStr" : "e61463f8efa94090b1f366cccfbbb444", //随机串     
           "package" : "u802345jgfjsdfgsdg888",     
           "signType" : "MD5",         //微信签名方式:     
           "paySign" : "70EA570631E4BB79628FBCA90534C63FF7FADD89" //微信签名 
       },
       function(res){     
           if(res.err_msg == "get_brand_wcpay_request:ok" ) {}     // 使用以上方式判断前端返回,微信团队郑重提示：res.err_msg将在用户支付成功后返回    ok，但并不保证它绝对可靠。 
       }
   ); 
}
if (typeof WeixinJSBridge == "undefined"){
   if( document.addEventListener ){
       document.addEventListener('WeixinJSBridgeReady', onBridgeReady, false);
   }else if (document.attachEvent){
       document.attachEvent('WeixinJSBridgeReady', onBridgeReady); 
       document.attachEvent('onWeixinJSBridgeReady', onBridgeReady);
   }
}else{
   onBridgeReady();
}

以上传入的参数package，即为prepay_id
详细文档见：https://pay.weixin.qq.com/wiki/doc/api/jsapi.php?chapter=7_7

下面讲的是获得参数来调用jsapi
我们调用JSAPI时，必须获得用户的openid，（trade_type=JSAPI，openid为必填参数。）
首先定义一个请求的对象：

package com.unstoppedable.protocol;


import com.thoughtworks.xstream.annotations.XStreamAlias;
import com.unstoppedable.common.Configure;
import com.unstoppedable.common.RandomStringGenerator;
import com.unstoppedable.common.Signature;

import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.Map;

@XStreamAlias("xml")
public class UnifiedOrderReqData {

    private String appid;
    private String mch_id;
    private String device_info;
    private String nonce_str;
    private String sign;
    private String body;
    private String detail;
    private String attach;
    private String out_trade_no;
    private String fee_type;
    private int total_fee;
    private String spbill_create_ip;
    private String time_start;
    private String time_expire;
    private String goods_tag;
    private String notify_url;
    private String trade_type;
    private String product_id;
    private String limit_pay;
    private String openid;

    private UnifiedOrderReqData(UnifiedOrderReqDataBuilder builder) {
        this.appid = builder.appid;
        this.mch_id = builder.mch_id;
        this.device_info = builder.device_info;
        this.nonce_str = RandomStringGenerator.getRandomStringByLength(32);
        this.body = builder.body;
        this.detail = builder.detail;
        this.attach = builder.attach;
        this.out_trade_no = builder.out_trade_no;
        this.fee_type = builder.fee_type;
        this.total_fee = builder.total_fee;
        this.spbill_create_ip = builder.spbill_create_ip;
        this.time_start = builder.time_start;
        this.time_expire = builder.time_expire;
        this.goods_tag = builder.goods_tag;
        this.notify_url = builder.notify_url;
        this.trade_type = builder.trade_type;
        this.product_id = builder.product_id;
        this.limit_pay = builder.limit_pay;
        this.openid = builder.openid;
        this.sign = Signature.getSign(toMap());
    }

    public String getAppid() {
        return appid;
    }

    public String getMch_id() {
        return mch_id;
    }

    public String getDevice_info() {
        return device_info;
    }

    public String getNonce_str() {
        return nonce_str;
    }

    public String getSign() {
        return sign;
    }

    public String getBody() {
        return body;
    }

    public String getDetail() {
        return detail;
    }

    public String getAttach() {
        return attach;
    }

    public String getOut_trade_no() {
        return out_trade_no;
    }

    public String getFee_type() {
        return fee_type;
    }

    public int getTotal_fee() {
        return total_fee;
    }

    public String getSpbill_create_ip() {
        return spbill_create_ip;
    }

    public String getTime_start() {
        return time_start;
    }

    public String getTime_expire() {
        return time_expire;
    }

    public String getGoods_tag() {
        return goods_tag;
    }

    public String getNotify_url() {
        return notify_url;
    }

    public String getTrade_type() {
        return trade_type;
    }

    public String getProduct_id() {
        return product_id;
    }

    public String getLimit_pay() {
        return limit_pay;
    }

    public String getOpenid() {
        return openid;
    }

    public Map<String, Object> toMap() {
        Map<String, Object> map = new HashMap<String, Object>();
        Field[] fields = this.getClass().getDeclaredFields();
        for (Field field : fields) {
            Object obj;
            try {
                obj = field.get(this);
                if (obj != null) {
                    map.put(field.getName(), obj);
                }
            } catch (IllegalArgumentException e) {
                e.printStackTrace();
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
        }
        return map;
    }


    public static class UnifiedOrderReqDataBuilder {
        private String appid;
        private String mch_id;
        private String device_info;
        private String body;
        private String detail;
        private String attach;
        private String out_trade_no;
        private String fee_type;
        private int total_fee;
        private String spbill_create_ip;
        private String time_start;
        private String time_expire;
        private String goods_tag;
        private String notify_url;
        private String trade_type;
        private String product_id;
        private String limit_pay;
        private String openid;

        /**
         * 使用配置中的 appid 和  mch_id
         *
         * @param body
         * @param out_trade_no
         * @param total_fee
         * @param spbill_create_ip
         * @param notify_url
         * @param trade_type
         */
        public UnifiedOrderReqDataBuilder(String body, String out_trade_no, Integer total_fee,
                                          String spbill_create_ip, String notify_url, String trade_type) {

            this(Configure.getAppid(), Configure.getMchid(), body, out_trade_no, total_fee,
                    spbill_create_ip, notify_url, trade_type);

        }

        public UnifiedOrderReqDataBuilder(String appid, String mch_id, String body, String out_trade_no, Integer total_fee,
                                          String spbill_create_ip, String notify_url, String trade_type) {
            if (appid == null) {
                throw new IllegalArgumentException("传入参数appid不能为null");
            }
            if (mch_id == null) {
                throw new IllegalArgumentException("传入参数mch_id不能为null");
            }
            if (body == null) {
                throw new IllegalArgumentException("传入参数body不能为null");
            }
            if (out_trade_no == null) {
                throw new IllegalArgumentException("传入参数out_trade_no不能为null");
            }
            if (total_fee == null) {
                throw new IllegalArgumentException("传入参数total_fee不能为null");
            }
            if (spbill_create_ip == null) {
                throw new IllegalArgumentException("传入参数spbill_create_ip不能为null");
            }
            if (notify_url == null) {
                throw new IllegalArgumentException("传入参数notify_url不能为null");
            }
            if (trade_type == null) {
                throw new IllegalArgumentException("传入参数trade_type不能为null");
            }
            this.appid = appid;
            this.mch_id = mch_id;
            this.body = body;
            this.out_trade_no = out_trade_no;
            this.total_fee = total_fee;
            this.spbill_create_ip = spbill_create_ip;
            this.notify_url = notify_url;
            this.trade_type = trade_type;
        }

        public UnifiedOrderReqDataBuilder setDevice_info(String device_info) {
            this.device_info = device_info;
            return this;
        }

        public UnifiedOrderReqDataBuilder setDetail(String detail) {
            this.detail = detail;
            return this;
        }

        public UnifiedOrderReqDataBuilder setAttach(String attach) {
            this.attach = attach;
            return this;
        }

        public UnifiedOrderReqDataBuilder setFee_type(String fee_type) {
            this.fee_type = fee_type;
            return this;
        }

        public UnifiedOrderReqDataBuilder setTime_start(String time_start) {
            this.time_start = time_start;
            return this;
        }

        public UnifiedOrderReqDataBuilder setTime_expire(String time_expire) {
            this.time_expire = time_expire;
            return this;
        }

        public UnifiedOrderReqDataBuilder setGoods_tag(String goods_tag) {
            this.goods_tag = goods_tag;
            return this;
        }

        public UnifiedOrderReqDataBuilder setProduct_id(String product_id) {
            this.product_id = product_id;
            return this;
        }

        public UnifiedOrderReqDataBuilder setLimit_pay(String limit_pay) {
            this.limit_pay = limit_pay;
            return this;
        }

        public UnifiedOrderReqDataBuilder setOpenid(String openid) {
            this.openid = openid;
            return this;
        }


        public UnifiedOrderReqData build() {

            if ("JSAPI".equals(this.trade_type) && this.openid == null) {
                throw new IllegalArgumentException("当传入trade_type为JSAPI时，openid为必填参数");
            }
            if ("NATIVE".equals(this.trade_type) && this.product_id == null) {
                throw new IllegalArgumentException("当传入trade_type为NATIVE时，product_id为必填参数");
            }
            return new UnifiedOrderReqData(this);
        }
    }


}

因为有些参数为必填，有些参数为选填。而且sign要等所有参数传入之后才能计算的出，所以这里用了builder模式。关于builder模式。关于每个参数的定义，参考说明文档https://pay.weixin.qq.com/wiki/doc/api/jsapi.php?chapter=9_1

我们选用httpclient进行网络传输。

package com.unstoppedable.common;

import com.thoughtworks.xstream.XStream;
import com.thoughtworks.xstream.io.xml.DomDriver;
import com.thoughtworks.xstream.io.xml.XmlFriendlyNameCoder;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.ResponseHandler;
import org.apache.http.client.config.RequestConfig;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.conn.ConnectTimeoutException;
import org.apache.http.conn.ConnectionPoolTimeoutException;
import org.apache.http.conn.ssl.SSLConnectionSocketFactory;
import org.apache.http.conn.ssl.SSLContexts;
import org.apache.http.entity.StringEntity;
import org.apache.http.impl.client.CloseableHttpClient;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;

import javax.net.ssl.SSLContext;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.net.SocketTimeoutException;
import java.security.KeyStore;

/**
 * Created by hupeng on 2015/7/28.
 */
public class HttpService {
    private static Log logger = LogFactory.getLog(HttpService.class);

    private static CloseableHttpClient httpClient = buildHttpClient();

    //连接超时时间，默认10秒
    private static int socketTimeout = 5000;

    //传输超时时间，默认30秒
    private static int connectTimeout = 5000;

    private static int requestTimeout = 5000;

    public static CloseableHttpClient buildHttpClient() {

        try {
            KeyStore keyStore = KeyStore.getInstance("PKCS12");
            FileInputStream instream = new FileInputStream(new File(Configure.getCertLocalPath()));//加载本地的证书进行https加密传输
            try {
                keyStore.load(instream, Configure.getCertPassword().toCharArray());//设置证书密码
            } finally {
                instream.close();
            }


            // Trust own CA and all self-signed certs
            SSLContext sslcontext = SSLContexts.custom()
                    .loadKeyMaterial(keyStore, Configure.getCertPassword().toCharArray())
                    .build();
            // Allow TLSv1 protocol only
            SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(
                    sslcontext,
                    new String[]{"TLSv1"},
                    null,
                    SSLConnectionSocketFactory.BROWSER_COMPATIBLE_HOSTNAME_VERIFIER);

            RequestConfig requestConfig = RequestConfig.custom()
                    .setConnectTimeout(connectTimeout)
                    .setConnectionRequestTimeout(requestTimeout)
                    .setSocketTimeout(socketTimeout).build();

            httpClient = HttpClients.custom()
                    .setDefaultRequestConfig(requestConfig)
                    .setSSLSocketFactory(sslsf)
                    .build();

            return httpClient;
        } catch (Exception e) {
            throw new RuntimeException("error create httpclient......", e);
        }
    }



    public static String doGet(String requestUrl) throws Exception {
        HttpGet httpget = new HttpGet(requestUrl);
        try {


            logger.debug("Executing request " + httpget.getRequestLine());
            // Create a custom response handler
            ResponseHandler<String> responseHandler = new ResponseHandler<String>() {

                @Override
                public String handleResponse(
                        final HttpResponse response) throws ClientProtocolException, IOException {
                    int status = response.getStatusLine().getStatusCode();
                    if (status >= 200 && status < 300) {
                        HttpEntity entity = response.getEntity();
                        return entity != null ? EntityUtils.toString(entity) : null;
                    } else {
                        throw new ClientProtocolException("Unexpected response status: " + status);
                    }
                }

            };

            return httpClient.execute(httpget, responseHandler);
        } finally {
            httpget.releaseConnection();
        }
    }

    public static String doPost(String url, Object object2Xml) {

        String result = null;

        HttpPost httpPost = new HttpPost(url);

        //解决XStream对出现双下划线的bug
        XStream xStreamForRequestPostData = new XStream(new DomDriver("UTF-8", new XmlFriendlyNameCoder("-_", "_")));

        //将要提交给API的数据对象转换成XML格式数据Post给API
        String postDataXML = xStreamForRequestPostData.toXML(object2Xml);

        logger.info("API，POST过去的数据是：");
        logger.info(postDataXML);

        //得指明使用UTF-8编码，否则到API服务器XML的中文不能被成功识别
        StringEntity postEntity = new StringEntity(postDataXML, "UTF-8");
        httpPost.addHeader("Content-Type", "text/xml");
        httpPost.setEntity(postEntity);

        //设置请求器的配置

        logger.info("executing request" + httpPost.getRequestLine());

        try {
            HttpResponse response = httpClient.execute(httpPost);

            HttpEntity entity = response.getEntity();

            result = EntityUtils.toString(entity, "UTF-8");

        } catch (ConnectionPoolTimeoutException e) {
            logger.error("http get throw ConnectionPoolTimeoutException(wait time out)", e);

        } catch (ConnectTimeoutException e) {
            logger.error("http get throw ConnectTimeoutException", e);

        } catch (SocketTimeoutException e) {
            logger.error("http get throw SocketTimeoutException", e);

        } catch (Exception e) {
            logger.error("http get throw Exception", e);

        } finally {
            httpPost.abort();
        }

        return result;
    }
}

然后是我们的总入口：

package com.unstoppedable.service;

import com.unstoppedable.common.Configure;
import com.unstoppedable.common.HttpService;
import com.unstoppedable.common.XMLParser;
import com.unstoppedable.protocol.UnifiedOrderReqData;
import org.xml.sax.SAXException;

import javax.xml.parsers.ParserConfigurationException;
import java.io.IOException;
import java.util.Map;

/**
 * Created by hupeng on 2015/7/28.
 */
public class WxPayApi {

    public static Map<String,Object> UnifiedOrder(UnifiedOrderReqData reqData) throws IOException, SAXException, ParserConfigurationException {
        String res  = HttpService.doPost(Configure.UNIFIED_ORDER_API, reqData);
        return XMLParser.getMapFromXML(res);
    }

    public static void main(String[] args) throws Exception {
        UnifiedOrderReqData reqData = new UnifiedOrderReqData.UnifiedOrderReqDataBuilder("appid", "mch_id", "body", "out_trade_no", 1, "spbill_create_ip", "notify_url", "JSAPI").setOpenid("openid").build();
        System.out.println(UnifiedOrder(reqData));


    }
}

返回的xml为：

<xml>
   <return_code><![CDATA[SUCCESS]]></return_code>
   <return_msg><![CDATA[OK]]></return_msg>
   <appid><![CDATA[wx2421b1c4370ec43b]]></appid>
   <mch_id><![CDATA[10000100]]></mch_id>
   <nonce_str><![CDATA[IITRi8Iabbblz1Jc]]></nonce_str>
   <sign><![CDATA[7921E432F65EB8ED0CE9755F0E86D72F]]></sign>
   <result_code><![CDATA[SUCCESS]]></result_code>
   <prepay_id><![CDATA[wx201411101639507cbf6ffd8b0779950874]]></prepay_id>
   <trade_type><![CDATA[JSAPI]]></trade_type>
</xml>

return_code 和result_code都为SUCCESS的时候会返回我们需要的prepay_id。。。

然后在jsapi中使用他就可以了。。

代码托管在https://github.com/hupengcool/wxpay_jsapi ，欢迎指正