微信小程序對接主要涉及的接口（僅供參考）

1.授權登錄需要獲取到用戶的唯一標識openid以及session_key會話密鑰

/**
* @Description: 獲取openid用戶唯一標識以及session_key會話密鑰
*/
@PostMapping("/getOpenId")
public Map<String,Object> getOpenId(String code){
    Map<String,Object>  map = new HashMap<>();
    //登錄憑證不能爲空
    if (null == code || code.length() == 0){
        map.put("errMessage","code 不能爲空!");
        return map;
    }
    //1.向微信服務器 試用登錄憑證 code 獲取session_key 和openid
    //請求參數
    Map<String,String> params = new HashMap<>();
    params.put("appid",StringInfo.APPID);
    params.put("secret",StringInfo.APPSECRET);
    params.put("js_code",code);
    params.put("grant_type","authorization_code");
    String result = HttpClientUtil.doGet("https://api.weixin.qq.com/sns/jscode2session?",params);
    JSONObject json = JSON.parseObject(result);
    System.out.println(json);

    if (json != null) {
        //當請求成功
        if (json.getString("errcode")==null) {
            map.put("openid",json.getString("openid"));//用戶的唯一標識
            map.put("sessionKey",json.getString("session_key"));//會話密鑰
            if (json.getString("unionid") != null) {
                map.put("unionid", json.getString("unionid"));//用戶在開放平臺的唯一標識符
            }
        }else{
            //當請求不成功的時候，將錯誤信息
            map.put("errMessage",json.getString("errmsg"));
        }
    }
    System.out.println(JSON.toJSON(map));
    return map;
}

2.獲取AccessToken

/**
* @Description:  獲取AccessToken
*/
@PostMapping("/getAccessToken")
public Map<String,Object> getAccessToken(){
    Map<String,Object> map = new HashMap<>();

    Map<String,String> params = new HashMap<>();
    //請求參數
    params.put("grant_type","client_credential");
    params.put("appid", StringInfo.APPID);
    params.put("secret",StringInfo.APPSECRET);

    //向微信服務端發起請求
    String result = HttpClientUtil.doGet("https://api.weixin.qq.com/cgi-bin/token?",params);
    //將結果轉爲json對象
    JSONObject json = JSON.parseObject(result);
    if (json != null) {
        if (json.getString("errcode") == null){
            map.put("accessToken",json.getString("access_token"));
            map.put("expiresIn",json.getString("expires_in"));
        }else {
            map.put("errMessage",json.getString("errmsg"));
        }
    }
    return map;
}

 

3.微信付款

/**
 * 支付接口
 * @param openid 用戶的唯一標識
 * @param body1 商品描述信息
 * @param total_fee1 金額
 * @return
 */
@RequestMapping("/WeiXinPay")
public @ResponseBody Object WeiXinPay(String openid,String body1,int total_fee1
      ) {
   try {
      String appid = userService.getUser().getAppid(); // 微信小程序--》“開發者ID”
      String mch_id = userService.getUser().getMchId(); // 商戶號，將該值賦值給partner
      String key = userService.getUser().getMchKey(); // 微信支付商戶平臺登錄）--》“API安全”--》“API密鑰”--“設置密鑰”（設置之後的那個值就是partnerkey，32位）
      LOGGER.debug(appid);
      LOGGER.debug(mch_id);
      LOGGER.debug(key);
      String body = body1; // 描述
      int total_fee = total_fee1; // 支付金額
       Date data = new Date();
      String notify_url = "https://www.baidu.com/weixinpay/notify"; // 自己發佈在公網回調鏈接，不然無法訪問
       String out_trade_no = IdUtils.genOrderName();//IdUtils-->見下面
      LOGGER.debug(out_trade_no);
      Map<Object, Object> map = WeiXinAtcion.me.weixinPlay(mch_id, appid,
            key, openid, total_fee, out_trade_no, notify_url, body);
      return map;
   } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
   }
   return TTResult.fail();
}

 

6.微信退款

/**
 * 
 * @param request
 * @param database
 * @param out_trade_no
 * @param all_total_fee
 * @param refund_fee
 * @return
 */
@RequestMapping("/WeiXinRefund")
public @ResponseBody Object WeiXinRefund(HttpServletRequest request,
      @RequestParam("out_trade_no") String out_trade_no,
      @RequestParam("all_total_fee") int all_total_fee,
      @RequestParam("refund_fee") int refund_fee) {
   try {
      LOGGER.debug("訂單號是--->"+out_trade_no);
      LOGGER.debug("總金額--->"+all_total_fee);
      LOGGER.debug("剩餘金額--->"+refund_fee);
      // out_trade_no 退款訂單號
      // all_total_fee 訂單金額
      // refund_fee  輸0  all_total_fee-refund_fee=退款的金額
      String appid = userService.getUser().getAppid(); // 微信小程序--》“開發者ID”
      String mch_id = userService.getUser().getMchId(); // 商戶號，將該值賦值給partner
      String key = userService.getUser().getMchKey(); // 微信支付商戶平臺登錄）--》“API安全”--》“API密鑰”--“設置密鑰”（設置之後的那個值就是partnerkey，32位）

      Map<String, String> refundmap = WeiXinAtcion.me.wechatRefund(
            request, mch_id, appid, key, out_trade_no, all_total_fee,
            refund_fee, userService.getUser().getCert());
      if (refundmap.get("return_code").equals("SUCCESS")) {
         if (refundmap.get("result_code").equals("FAIL")) {
            LOGGER.debug("退款失敗:原因" + refundmap.get("err_code_des"));
         } else {
            LOGGER.debug("退款成功");
            return TTResult.ok();
         }
      } else {
         LOGGER.debug("退款失敗:原因" + refundmap.get("return_ms"));
         return TTResult.fail();
      }
   } catch (Exception e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
   }
   return TTResult.fail();
}

 

5.將調用微信付款、退款封裝

import java.io.BufferedOutputStream;
import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.UnsupportedEncodingException;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.SortedMap;
import java.util.TreeMap;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.dom4j.Document;
import org.dom4j.DocumentException;
import org.dom4j.Element;
import org.dom4j.io.SAXReader;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;

import com.mj.mall.user.service.UserService;
import com.mj.pay.util.WXUtil;

@Controller
public class WeiXinAtcion {
    public static final WeiXinAtcion me = new WeiXinAtcion();
    private static final Logger LOGGER = LoggerFactory
            .getLogger(WeiXinAtcion.class);
    @Autowired
    private UserService userService;

    /**
     * 退款
     */
    public static Map<String, String> wechatRefund(HttpServletRequest request, String mch_id, String appid, String key, String out_trade_no, int all_total_fee, int refund_fee, String apiclient_certLocationp12) throws Exception {

        SortedMap<Object, Object> packageParams = new TreeMap<Object, Object>();
        LOGGER.debug("走到退款函數了");
        packageParams.put("appid", appid);
        packageParams.put("mch_id", mch_id);
        packageParams.put("op_user_id", mch_id);
        packageParams.put("nonce_str", WXUtil.generate());
        packageParams.put("out_trade_no", out_trade_no);
        packageParams.put("out_refund_no", WXUtil.generate());
        packageParams.put("total_fee", String.valueOf(all_total_fee));
        packageParams.put("refund_fee", String.valueOf(all_total_fee - refund_fee));
        String sign = WXUtil.createSign_ChooseWXPay("UTF-8", packageParams, key);
        packageParams.put("sign", sign);
        String XML = WXUtil.getRequestXml(packageParams);
        LOGGER.debug("退款函數結束,接下來執行退款操作");
        return WXUtil.doRefund(request, "https://api.mch.weixin.qq.com/secapi/pay/refund", XML, mch_id, apiclient_certLocationp12);

    }

    /**
     * 生成微信訂單
     */
    public SortedMap<Object, Object> weixinPlay(String mch_id, String appid, String key, String openid, int total_fee, String out_trade_no, String notify_url, String body) throws UnsupportedEncodingException, DocumentException {

        SortedMap<Object, Object> paymentPo = new TreeMap<Object, Object>();
        paymentPo.put("appid", appid);
        paymentPo.put("mch_id", mch_id);
        paymentPo.put("nonce_str", WXUtil.generate());
        paymentPo.put("body", body);
        paymentPo.put("out_trade_no", out_trade_no);
        paymentPo.put("total_fee", String.valueOf(total_fee));
        paymentPo.put("spbill_create_ip", "120.77.171.156");//此處是公網ip
        paymentPo.put("notify_url", notify_url);
        paymentPo.put("trade_type", "JSAPI");
        paymentPo.put("openid", openid);

        String sign = WXUtil.createSign_ChooseWXPay("UTF-8", paymentPo, key);
        paymentPo.put("sign", sign);
        String param = WXUtil.getRequestXml(paymentPo);
        ;

        String request = WXUtil.httpRequest("https://api.mch.weixin.qq.com/pay/unifiedorder", "POST", param);
        Map<String, String> map = new HashMap<String, String>();         // 將解析結果存儲在HashMap中
        InputStream in = new ByteArrayInputStream(request.getBytes());
        SAXReader reader = new SAXReader();                              // 讀取輸入流
        Document document = reader.read(in);

        Element root = document.getRootElement();                        // 得到xml根元素
        @SuppressWarnings("unchecked")                                   // 得到根元素的所有子節點
                List<Element> elementList = root.elements();
        for (Element element : elementList) {
            map.put(element.getName(), element.getText());
        }
        SortedMap<Object, Object> result = new TreeMap<Object, Object>();

        LOGGER.debug("第一次簽名返回碼" + map.get("return_code"));
        LOGGER.debug("第一次簽名返回結果" + map.get("return_msg"));
        //第一次簽名成功
        if (map.get("return_code").equals("SUCCESS")) {                  // 業務結果
            String nonceStr = WXUtil.generate();
            Long timeStamp = System.currentTimeMillis() / 1000;
            SortedMap<Object, Object> params = new TreeMap<Object, Object>();

            params.put("appId", appid);
            params.put("nonceStr", nonceStr);
            params.put("package", "prepay_id=" + map.get("prepay_id"));
            params.put("signType", "MD5");
            params.put("timeStamp", timeStamp);

            //第二次簽名成功
            LOGGER.debug("開始第二次簽名");
            String paySign = WXUtil.createSign_ChooseWXPay("UTF-8", params, key);
            result.put("paySign", paySign);
            result.put("timeStamp", timeStamp + "");
            result.put("nonceStr", nonceStr);
            result.put("out_trade_no", paymentPo.get("out_trade_no"));
            result.put("package", "prepay_id=" + map.get("prepay_id"));
            result.put("return_code", "SUCCESS");
        } else {
            result.put("return_code", "Fail");
            result.put("return_msg", map.get("return_msg"));

        }
        return result;
    }

    /**
     * 支付成功回調函數
     */
    @RequestMapping("/weixinpay/notify")
    public void weixinpay_notify(HttpServletRequest request, HttpServletResponse response) throws Exception {
        InputStream inputStream;
        StringBuffer sb = new StringBuffer();
        inputStream = request.getInputStream();
        String s;
        BufferedReader in = new BufferedReader(new InputStreamReader(inputStream, "UTF-8"));
        while ((s = in.readLine()) != null) {
            sb.append(s);
        }
        in.close();
        inputStream.close();
        Map<String, String> m = new HashMap<String, String>();
        m = WXUtil.doXMLParse(sb.toString());
        SortedMap<Object, Object> packageParams = new TreeMap<Object, Object>();
        Iterator it = m.keySet().iterator();
        while (it.hasNext()) {
            String parameter = (String) it.next();
            String parameterValue = m.get(parameter);
            String v = "";
            if (null != parameterValue) {
                v = parameterValue.trim();
            }
            packageParams.put(parameter, v);
        }
        //String key = ""; //祕鑰
        String key = userService.getUser().getMchKey(); //祕鑰
        if (WXUtil.isTenpaySign("UTF-8", packageParams, key)) {
            String resXml = "";
            if ("SUCCESS".equals((String) packageParams.get("result_code"))) {

                //得到返回的參數
                String openid = (String) packageParams.get("openid");
                String transaction_id = (String) packageParams.get("transaction_id");
                String out_trade_no = (String) packageParams.get("out_trade_no");
                String total_fee = (String) packageParams.get("total_fee");
                Float fee = Float.parseFloat(total_fee) / 100;
                //這裏可以寫你需要的業務
                System.out.println("openid---->" + openid);
                System.out.println("transaction_id---->" + transaction_id);
                System.out.println("out_trade_no---->" + out_trade_no);
                System.out.println("total_fee---->" + total_fee);
                System.out.println("fee---->" + fee);
                resXml = "<xml>" + "<return_code><![CDATA[SUCCESS]]></return_code>"
                        + "<return_msg><![CDATA[OK]]></return_msg>" + "</xml> ";
                BufferedOutputStream out = new BufferedOutputStream(response.getOutputStream());
                out.write(resXml.getBytes());
                out.flush();
                out.close();
            } else {
                System.out.println("回調失敗");
            }
        } else {
            System.out.println("回調失敗");
        }
    }

}

8.WXUtil工具類

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URI;
import java.net.URL;
import java.security.KeyStore;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Map.Entry;
import java.util.Set;
import java.util.SortedMap;
import java.util.UUID;

import javax.net.ssl.SSLContext;
import javax.servlet.http.HttpServletRequest;

import org.apache.http.HttpEntity;
import org.apache.http.client.methods.CloseableHttpResponse;
import org.apache.http.client.methods.HttpPost;
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 org.jdom.Document;
import org.jdom.Element;
import org.jdom.JDOMException;
import org.jdom.input.SAXBuilder;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class WXUtil {
   
   private static final Logger LOGGER = LoggerFactory.getLogger(WXUtil.class);
   /**
    * 隨機字符串
    * @return
    */
   public static String generate() {
      return UUID.randomUUID().toString().trim().replaceAll("-", "");
   }
   
   /**
    * 解析xml,返回第一級元素鍵值對。如果第一級元素有子節點，則此節點的值是子節點的xml數據。
    */
   public static Map doXMLParse(String strxml) throws JDOMException, IOException {
      strxml = strxml.replaceFirst("encoding=\".*\"", "encoding=\"UTF-8\"");

      if(null == strxml || "".equals(strxml)) {
         return null;
      }
      Map m = new HashMap();
      InputStream in = new ByteArrayInputStream(strxml.getBytes("UTF-8"));
      SAXBuilder builder = new SAXBuilder();
      Document doc = builder.build(in);
      Element root = doc.getRootElement();
      List list = root.getChildren();
      Iterator it = list.iterator();
      while(it.hasNext()) {
         Element e = (Element) it.next();
         String k = e.getName();
         String v = "";
         List children = e.getChildren();
         if(children.isEmpty()) {
            v = e.getTextNormalize();
         } else {
            v = WXUtil.getChildrenText(children);
         }
         m.put(k, v);
      }
      
      //關閉流
      in.close();
      
      return m;
   }
   
   /**
    * 獲取子結點的xml
    * @param children
    * @return String
    */
   public static String getChildrenText(List children) {
      StringBuffer sb = new StringBuffer();
      if(!children.isEmpty()) {
         Iterator it = children.iterator();
         while(it.hasNext()) {
            Element e = (Element) it.next();
            String name = e.getName();
            String value = e.getTextNormalize();
            List list = e.getChildren();
            sb.append("<" + name + ">");
            if(!list.isEmpty()) {
               sb.append(WXUtil.getChildrenText(list));
            }
            sb.append(value);
            sb.append("</" + name + ">");
         }
      }
      return sb.toString();
   }
   /**
    * 將請求參數轉換爲xml格式的string字符串，微信服務器接收的是xml格式的字符串
    */
   public static String getRequestXml(SortedMap<Object, Object> parameters) {
      StringBuffer sb = new StringBuffer();
      sb.append("<xml>");
      Set<Entry<Object, Object>> es = parameters.entrySet();
      Iterator<Entry<Object, Object>> it = es.iterator();
      while (it.hasNext()) {
         Map.Entry<Object, Object> entry = (Map.Entry<Object, Object>) it.next();
         String k = (String) entry.getKey();
         String v = (String) entry.getValue();
         
         if ("attach".equalsIgnoreCase(k) || "body".equalsIgnoreCase(k) || "sign".equalsIgnoreCase(k)) {
            sb.append("<" + k + ">" + "<![CDATA[" + v + "]]></" + k + ">");
         } else {
            sb.append("<" + k + ">" + v + "</" + k + ">");
         }
      }
      sb.append("</xml>");
      return sb.toString();
   }
   
   /**
    * sign簽名，必須使用MD5簽名，且編碼爲UTF-8
    */
   public static String createSign_ChooseWXPay(String characterEncoding, SortedMap<Object, Object> parameters, String key) {
      StringBuffer sb = new StringBuffer();
      Set<Entry<Object, Object>> es = parameters.entrySet();
      Iterator<Entry<Object, Object>> it = es.iterator();
      while (it.hasNext()) {
         Map.Entry<Object, Object> entry = (Map.Entry<Object, Object>) it.next();
         String k = (String) entry.getKey();
         Object v = entry.getValue();
         if (null != v && !"".equals(v) && !"sign".equals(k) && !"key".equals(k)) {
            sb.append(k + "=" + v + "&");
         }
      }
      /** 支付密鑰必須參與加密，放在字符串最後面 */
      sb.append("key=" + key);
      String sign = MD5Util.MD5Encode(sb.toString(), characterEncoding).toUpperCase();
      return sign;
   }
   

    /**
     * 
     * @param requestUrl 請求地址
     * @param requestMethod 請求方法
     * @param outputStr 參數
     */
    public static String httpRequest(String requestUrl,String requestMethod,String outputStr){
        // 創建SSLContext
        StringBuffer buffer=null;
        try{
        URL url = new URL(requestUrl);
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setRequestMethod(requestMethod);
        conn.setDoOutput(true);
        conn.setDoInput(true);
        conn.connect();

        //往服務器端寫內容
        if(null !=outputStr){
            OutputStream os=conn.getOutputStream();
            os.write(outputStr.getBytes("utf-8"));
            os.close();
        }
        // 讀取服務器端返回的內容
        InputStream is = conn.getInputStream();
        InputStreamReader isr = new InputStreamReader(is, "utf-8");
        BufferedReader br = new BufferedReader(isr);
        buffer = new StringBuffer();
        String line = null;
        while ((line = br.readLine()) != null) {
             buffer.append(line);
         }
        }catch(Exception e){
            e.printStackTrace();
        }
        return buffer.toString();
        }   
    public static String urlEncodeUTF8(String source){
        String result=source;
        try {
            result=java.net.URLEncoder.encode(source, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return result;
    }
       
   /**
    * 退款
     */
   public static Map<String, String> doRefund(HttpServletRequest request,String url,String data,String partner,String apiclient_certLocation) throws Exception {
   // p12證書的位置
         // 微信公衆平臺：“微信支付”--》“商戶信息”--》“交易數據”--》“詳情請登錄微信支付商戶平臺查看”（登錄）--》“API安全”--》“API證書”--》“下載證書”
         // 下載證書後將apiclient_cert.p12放在src目錄下面（出於安全考慮，請自行下載自己的證書）
         KeyStore keyStore = KeyStore.getInstance("PKCS12");
         String url2 = request.getSession().getServletContext().getRealPath("/")
               + "images/cert/" + apiclient_certLocation;
         LOGGER.debug("url2--->"+url2);
         File file=new File(url2);
         LOGGER.debug("new了一個file");
         FileInputStream instream = new FileInputStream(file);// P12文件目錄
         LOGGER.debug("退款路徑結束");
        try {
            keyStore.load(instream, partner.toCharArray());
        } finally {
            instream.close();
        }
        SSLContext sslcontext = SSLContexts.custom().loadKeyMaterial(keyStore, partner.toCharArray()).build();
        SSLConnectionSocketFactory sslsf = new SSLConnectionSocketFactory(sslcontext,new String[] { "TLSv1" }, null,SSLConnectionSocketFactory.BROWSER_COMPATIBLE_HOSTNAME_VERIFIER);
        CloseableHttpClient httpclient = HttpClients.custom().setSSLSocketFactory(sslsf).build();
        try {
           HttpPost httpost = new HttpPost(url); // 設置響應頭信息
           httpost.addHeader("Connection", "keep-alive");
           httpost.addHeader("Accept", "*/*");
           httpost.addHeader("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8");
           httpost.addHeader("Host", "api.mch.weixin.qq.com");
           httpost.addHeader("X-Requested-With", "XMLHttpRequest");
           httpost.addHeader("Cache-Control", "max-age=0");
           httpost.addHeader("User-Agent", "Mozilla/4.0 (compatible; MSIE 8.0; Windows NT 6.0) ");
          httpost.setEntity(new StringEntity(data, "UTF-8"));
            CloseableHttpResponse response = httpclient.execute(httpost);
            try {
               HttpEntity entity = response.getEntity();
                String jsonStr = EntityUtils.toString(response.getEntity(), "UTF-8");
                EntityUtils.consume(entity);
                return WXUtil.doXMLParse(jsonStr);
            } finally {
                response.close();
            }
        } finally {
            httpclient.close();
        }
    }
    
    /** 
     * 是否簽名正確,規則是:按參數名稱a-z排序,遇到空值的參數不參加簽名。 
     */  
    public static boolean isTenpaySign(String characterEncoding, SortedMap<Object, Object> packageParams, String API_KEY) {  
        StringBuffer sb = new StringBuffer();  
        Set es = packageParams.entrySet();  
        Iterator it = es.iterator();  
        while(it.hasNext()) {  
            Map.Entry entry = (Map.Entry)it.next();  
            String k = (String)entry.getKey();  
            String v = (String)entry.getValue();  
            if(!"sign".equals(k) && null != v && !"".equals(v)) {  
                sb.append(k + "=" + v + "&");  
            }  
        }  
        sb.append("key=" + API_KEY);  
        //算出摘要  
        String mysign = MD5Util.MD5Encode(sb.toString(), characterEncoding).toLowerCase();  
        String tenpaySign = ((String)packageParams.get("sign")).toLowerCase();  
          
        //System.out.println(tenpaySign + "    " + mysign);  
        return tenpaySign.equals(mysign);  
    }  

}

 

9.IdUtils工具類

import java.util.Random;

public class IdUtils {
   /**
    * 圖片名生成
    */
   public static String genImageName() {
      //取當前時間的長整形值包含毫秒
      long millis = System.currentTimeMillis();
      //long millis = System.nanoTime();
      //加上三位隨機數
      Random random = new Random();
      int end3 = random.nextInt(999);
      //如果不足三位前面補0
      String str = millis + String.format("%03d", end3);
      
      return str;
   }
   
   /**
    * 訂單號生成
    * @return
    */
   public static String genOrderName() {
      //取當前時間的長整形值包含毫秒
      long millis = System.currentTimeMillis();
      //long millis = System.nanoTime();
      //加上六位隨機數
      Random random = new Random();
      long end6 = random.nextInt(999999);
      //如果不足三位前面補0
      String str = millis + String.format("%06d", end6);
      
      return str;
   }
}

 

10.MD5Util工具類

import java.security.MessageDigest;
public class MD5Util {

   private static String byteArrayToHexString(byte b[]) {
      StringBuffer resultSb = new StringBuffer();
      for (int i = 0; i < b.length; i++)
         resultSb.append(byteToHexString(b[i]));

      return resultSb.toString();
   }

   private static String byteToHexString(byte b) {
      int n = b;
      if (n < 0)
         n += 256;
      int d1 = n / 16;
      int d2 = n % 16;
      return hexDigits[d1] + hexDigits[d2];
   }

    public static String MD5Encode(String origin, String charsetname) {  
           String resultString = null;  
           try {  
               resultString = new String(origin);  
               MessageDigest md = MessageDigest.getInstance("MD5");  
               if (charsetname == null || "".equals(charsetname))  
                   resultString = byteArrayToHexString(md.digest(resultString  
                           .getBytes()));  
               else  
                   resultString = byteArrayToHexString(md.digest(resultString  
                           .getBytes(charsetname)));  
           } catch (Exception exception) {  
           }  
           return resultString;  
       }  
   
   private static final String hexDigits[] = { "0", "1", "2", "3", "4", "5",
      "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };
}