微信退款開發需要的步驟比較多，首先是按照官方文檔生成證書，下載下來是一個zip。有時候會很疑惑，這個證書怎麼用？實際上呢，就是發送接口的時候帶上證書就可了。看一個具體的例子吧，以JSAPI微信退款為例。1、首先是發起退款申請因為每次發起退款請求，都要帶上證書，如果直接從證書文件讀取内容，速度很慢，因此将證書内容存放于内存中。大緻如下：

@Getter @Configuration public class WxConfig { /** * 微信支付，證書存放父路徑 證書名稱：商戶id_cert.p12 商戶id_cert.pem 商戶id_key.pem */ @Value("${wx.apiCertLocation}") private String apiCertLocation; /** * 從 商戶id_cert.p12文件讀取内容，放入字節數組。(不要每次都從io中獲取數據，太慢) */ private byte [] certData; /** * 将商戶id_cert.p12文件内容轉換成流 * @return */ public InputStream getCertStream() throws IOException { if(certData==null||certData.length==0){ InputStream certStream = new FileInputStream(apiCertLocation mchId "_cert.p12"); this.certData = IOUtils.toByteArray(certStream); certStream.close(); } return new ByteArrayInputStream(this.certData); } }

下面就是發送帶證書的請求了：

InputStream certStream = wxConfig.getCertStream(); String xmlResult = requestWithApiCert(REFUND_URL,xmlStr,mchId(),certStream); certStream.close();

具體的工具類：

/** * 微信支付 帶API證書的請求 * @return * @throws Exception */ public static String requestWithApiCert(String url, String data, String mchId,InputStream certStream) throws Exception { BasicHttpClientConnectionManager connManager; // 證書 char[] password = mchId.toCharArray(); KeyStore ks = KeyStore.getInstance("PKCS12"); ks.load(certStream, password); // 實例化密鑰庫 & 初始化密鑰工廠 KeyManagerFactory kmf = KeyManagerFactory.getInstance(KeyManagerFactory.getDefaultAlgorithm()); kmf.init(ks, password); // 創建 SSLContext SSLContext sslContext = SSLContext.getInstance("TLS"); sslContext.init(kmf.getKeyManagers(), null, new SecureRandom()); SSLConnectionSocketFactory sslConnectionSocketFactory = new SSLConnectionSocketFactory( sslContext, new String[]{"TLSv1"}, null, new DefaultHostnameVerifier()); connManager = new BasicHttpClientConnectionManager( RegistryBuilder.<ConnectionSocketFactory>create() .register("http", PlainConnectionSocketFactory.getSocketFactory()) .register("https", sslConnectionSocketFactory) .build(), null, null, null ); HttpClient httpClient = HttpClientBuilder.create() .setConnectionManager(connManager) .build(); HttpPost httpPost = new HttpPost(url); RequestConfig requestConfig = RequestConfig.custom().build(); httpPost.setConfig(requestConfig); StringEntity postEntity = new StringEntity(data, "UTF-8"); httpPost.addHeader("Content-Type", "text/xml"); httpPost.setEntity(postEntity); HttpResponse httpResponse = httpClient.execute(httpPost); HttpEntity httpEntity = httpResponse.getEntity(); return EntityUtils.toString(httpEntity, "UTF-8"); }

微信退款回調中，有一個req_info字段，需要解密才可以使用:

/** * 注意此方法 如果報錯：Illegal key size or default parameters 一般需要到oracle官網下載local_policy.jar US_export_policy.jar 包進行替換，路徑：jdk安裝路徑/jre/lib/security * @param reqInfo * @param apiKey * @return reqInfo的xml字符串 * @throws Exception */ public static String getReqInfoXml(String reqInfo,String apiKey) throws Exception{ Cipher cipher = Cipher.getInstance("AES/ECB/PKCS5Padding"); MessageDigest md5 = MessageDigest.getInstance("MD5"); md5.update(apiKey.getBytes()); String keyMd5String = (new BigInteger(1, md5.digest())).toString(16).toLowerCase(); SecretKeySpec key = new SecretKeySpec(keyMd5String.getBytes(), "AES"); cipher.init(2, key); return new String(cipher.doFinal(Base64.decodeBase64(reqInfo))); }

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