JS 调用微信扫一扫功能

1.第一步：

设置调用微信js安全域名，就可以在该域名下调用微信的js接口

2.第二步：

将下面的js附在需要调用微信扫一扫的页面上，前提是需要引入微信的js[]

3.第三步：

参考官方文档 https://mp.weixin.qq.com/wiki?t=resource/res_main&id=mp1421141115&token=876521668&lang=zh_CN

通过后台获取js权限签名jsapi_ticket【参考文档：http://mp.weixin.qq.com/wiki/7/aaa137b55fb2e0456bf8dd9148dd613f.html#.E9.99.84.E5.BD.951-JS-SDK.E4.BD.BF.E7.94.A8.E6.9D.83.E9.99.90.E7.AD.BE.E5.90.8D.E7.AE.97.E6.B3.95】

后台获取签名代码：

package com.epoch.wap.common;
import java.io.IOException;
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.Formatter;
import java.util.HashMap;
import java.util.Map;
import java.util.UUID;
import org.apache.http.HttpResponse;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.HttpClients;
import org.apache.http.util.EntityUtils;
import com.epoch.common.utils.JsonUtil;
/** 
 * 官方给的使用js的验证工具 
 * @author Administrator 
 * 
 */ 
public class JsSignUtil { 
  public static String accessToken = null; 
  public static Map<String, Object> sign(String url) {  
    String sendUrl = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=**appid**&secret= **secret**";
    String result = getHttpResult(sendUrl);
    Object accessResult = JsonUtil.getValueFromJson(result, "access_token");
    String signUrl = "https://api.weixin.qq.com/cgi-bin/ticket/getticket?access_token="+accessResult.toString()+"&type=jsapi";
    String resultSign = getHttpResult(signUrl);
    Object ticket = JsonUtil.getValueFromJson(resultSign, "ticket");
    Map<String, Object> ret = new HashMap<String, Object>(); 
    String nonce_str = create_nonce_str(); 
    String timestamp = create_timestamp(); 
    String string1; 
    String signature = ""; 
    //注意这里参数名必须全部小写，且必须有序 
    string1 = "jsapi_ticket=" + ticket +
         "&noncestr=" + nonce_str + 
         "&timestamp=" + timestamp + 
         "&url=" + url; 
    try 
    { 
      MessageDigest crypt = MessageDigest.getInstance("SHA-1"); 
      crypt.reset(); 
      crypt.update(string1.getBytes("UTF-8")); 
      signature = byteToHex(crypt.digest()); 
    } 
    catch (NoSuchAlgorithmException e) 
    { 
      e.printStackTrace(); 
    } 
    catch (UnsupportedEncodingException e) 
    { 
      e.printStackTrace(); 
    } 
    ret.put("url", url); 
    ret.put("nonceStr", nonce_str); 
    ret.put("timestamp", timestamp); 
    ret.put("signature", signature); 
    ret.put("jsapi_ticket", ticket); 
    ret.put("appId", "wx154f74654ae04891");
    return ret; 
  } 
  /** 
   * 随机加密 
   * @param hash 
   * @return 
   */ 
  private static String byteToHex(final byte[] hash) { 
    Formatter formatter = new Formatter(); 
    for (byte b : hash) 
    { 
      formatter.format("%02x", b); 
    } 
    String result = formatter.toString(); 
    formatter.close(); 
    return result; 
  } 
  /*
   * 获取访问地址链接返回值
   */
  private static String getHttpResult(String url) {
    String result = "";
    HttpGet httpRequest = new HttpGet(url);
    try {
      HttpResponse httpResponse = HttpClients.createDefault().execute(httpRequest);
      if (httpResponse.getStatusLine().getStatusCode() == 200) {
        result = EntityUtils.toString(httpResponse.getEntity());
      }
    } catch (ClientProtocolException e) {
      e.printStackTrace();
      result = e.getMessage().toString();
    } catch (IOException e) {
      e.printStackTrace();
      result = e.getMessage().toString();
    }
    return result;
  }
  /** 
   * 产生随机串--由程序自己随机产生 
   * @return 
   */ 
  private static String create_nonce_str() { 
    return UUID.randomUUID().toString(); 
  } 
  /** 
   * 由程序自己获取当前时间 
   * @return 
   */ 
  private static String create_timestamp() { 
    return Long.toString(System.currentTimeMillis() / 1000); 
  } 
}

官方文档示例：

参考以下文档获取access_token（有效期7200秒，开发者必须在自己的服务全局缓存access_token）：../15/54ce45d8d30b6bf6758f68d2e95bc627.html

用第一步拿到的access_token 采用http GET方式请求获得jsapi_ticket（有效期7200秒，开发者必须在自己的服务全局缓存jsapi_ticket）：https://api.weixin.qq.com/cgi-bin/ticket/getticket?access_token=ACCESS_TOKEN&type=jsapi

4 第四步：

前台进入页面：`

@RequestMapping(value = "/tiaoma")
public String tiaoma( HttpServletRequest request,GoodsVO goods) throws Exception {
  String Url=request.getRequestURL()+"?"+request.getQueryString().toString();;
  Map<String, Object> resMap = new HashMap<String, Object>();
  resMap = JsSignUtil.sign(Url);
  request.setAttribute("nonceStr", resMap.get("nonceStr"));
  request.setAttribute("timestamp", resMap.get("timestamp"));
  request.setAttribute("signature", resMap.get("signature"));
  request.setAttribute("appId", resMap.get("appId"));
  request.setAttribute("url", resMap.get("url"));
  request.setAttribute("jsapi_ticket",                 resMap.get("jsapi_ticket"));
  return "index/tiaoma";
}`