本文实例讲述了微信小程序webview实现长按点击识别二维码功能。分享给大家供大家参考，具体如下：

场景：微信小程序，使用webview控件。需求：点击图片后长按图片出现“识别二维码”

1、JS代码：

<script src="http://res.wx.qq.com/open/js/jweixin-1.2.0.js"></script>
<script type="text/javascript">
$(function(){
 var returnData = false;
 $.ajax({
 type : "get",
 url : 'http://app.ka.com/m/config.php',
 data : [],
 async : false,
 success: function(data,textStatus,jqXHR){
 returnData = data;
 //console.log(returnData);
 }
 });//end ajax
 var returnData = eval('(' + returnData + ')');
 console.log(returnData);
 var appId = returnData.appId;
 var timestamp = returnData.timestamp;
 var nonceStr = returnData.nonceStr;
 var signature = returnData.signature;
 wx.config({
 debug: true, //调试阶段建议开启
 appId: appId,
 timestamp: timestamp,
 nonceStr: nonceStr,
 signature: signature,
 jsApiList: [
 /*
 * 所有要调用的 API 都要加到这个列表中
 * 这里以图像接口为例
 */
 "chooseImage",
 "previewImage",
 "uploadImage",
 "downloadImage",
 "scanQRCode"
 ]
 });
 wx.ready(function() {
 //alert(3);
 wx.checkJsApi({
 jsApiList : ['scanQRCode','previewImage'],
 success : function(res) {
 }
 });
 $("img").click(function(){
 var url = "http://app.ka.com/"+$(this).attr("src");
 wx.previewImage({
 current: url, // 当前显示图片的http链接
 urls: [url] // 需要预览的图片http链接列表
 });
 });
 });
 wx.error(function(res){
 // config信息验证失败会执行error函数，如签名过期导致验证失败，具体错误信息可以打开config的debug模式查看，也可以在返回的res参数中查看，对于SPA可以在这里更新签名。
 console.log(res);
 });
});
</script>

2、服务端代码（获取config配置信息）：

<?php
date_default_timezone_set("Asia/Shanghai");
$jssdk = new Jssdk();
$signPackage = $jssdk->getSignPackage();
echo json_encode($signPackage);exit;
class Jssdk
{
 private $_CI;
 private $appId;
 private $appSecret;
 public function __construct($appId='wx666666', $appSecret='ee32') {
 $this->appId = $appId;
 $this->appSecret = $appSecret;
 }
 public function getSignPackage() {
 $jsapiTicket = $this->getJsApiTicket();
 // 注意 URL 一定要动态获取，不能 hardcode.
 $protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS'] !== 'off' || $_SERVER['SERVER_PORT'] == 443) ? "https://" : "http://";
 $url = "$protocol$_SERVER[HTTP_HOST]$_SERVER[REQUEST_URI]";
 $timestamp = time();
 $nonceStr = $this->createNonceStr();
 // 这里参数的顺序要按照 key 值 ASCII 码升序排序
 $string = "jsapi_ticket=$jsapiTicket&noncestr=$nonceStr×tamp=$timestamp&url=$url";
 $signature = sha1($string);
 $signPackage = array(
 "appId" => $this->appId,
 "nonceStr" => $nonceStr,
 "timestamp" => $timestamp,
 "url" => $url,
 "signature" => $signature,
 "rawString" => $string,
 'jsapiTicket' =>$jsapiTicket,
 );
 return $signPackage;
 }
 private function createNonceStr($length = 16) {
 $chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
 $str = "";
 for ($i = 0; $i < $length; $i++) {
 $str .= substr($chars, mt_rand(0, strlen($chars) - 1), 1);
 }
 return $str;
 }
 private function getJsApiTicket() {
 // jsapi_ticket 应该全局存储与更新，以下代码以写入到文件中做示例
 $data = $this->get_php_file("jsapi_ticket");
 //echo $data['expire_time'].'------'.time();
 //print_r($data);exit;
 if (!isset($data['jsapi_ticket']) || (isset($data['expire_time']) && $data['expire_time'] < time())) {
 //echo 1111;
 $accessToken = $this->getAccessToken();
 // 如果是企业号用以下 URL 获取 ticket
 // $url = "https://qyapi.weixin.qq.com/cgi-bin/get_jsapi_ticket?access_token=$accessToken";
 $url = "https://api.weixin.qq.com/cgi-bin/ticket/getticket?type=jsapi&access_token=$accessToken";
 //echo $url;
 $res = json_decode($this->httpGet($url), true);
 $ticket = isset($res['ticket']) ? $res['ticket'] : false;
 if ($ticket) {
 $data['expire_time'] = time() + 7160;
 $data['token_value'] = $ticket;
 $this->set_php_file("jsapi_ticket", $data);
 }
 } else {
 //echo 22222;
 $ticket = $data['jsapi_ticket'];
 }
 return $ticket;
 }
 public function getAccessToken() {
 // access_token 应该全局存储与更新，以下代码以写入到文件中做示例
 $data = $this->get_php_file("access_token");
 if (!isset($data['access_token']) || (isset($data['expire_time']) && $data['expire_time'] < time())) {
 // 如果是企业号用以下URL获取access_token
 // $url = "https://qyapi.weixin.qq.com/cgi-bin/gettoken?corpid=$this->appId&corpsecret=$this->appSecret";
 $url = "https://api.weixin.qq.com/cgi-bin/token?grant_type=client_credential&appid=$this->appId&secret=$this->appSecret";
 $res = json_decode($this->httpGet($url));
 //var_dump($res);exit;
 $access_token = $res->access_token;
 if ($access_token) {
 $data['expire_time'] = time() + 7160;
 $data['token_value'] = $access_token;
 $this->set_php_file("access_token", $data);
 }
 } else {
 $access_token = $data['access_token'];
 }
 return $access_token;
 }
 private function httpGet($url) {
 $curl = curl_init();
 curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
 curl_setopt($curl, CURLOPT_TIMEOUT, 500);
 // 为保证第三方服务器与微信服务器之间数据传输的安全性，所有微信接口采用https方式调用，必须使用下面2行代码打开ssl安全校验。
 // 如果在部署过程中代码在此处验证失败，请到 http://curl.haxx.se/ca/cacert.pem 下载新的证书判别文件。
 curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, 0);
 curl_setopt($curl, CURLOPT_SSL_VERIFYHOST, 0);
 curl_setopt($curl, CURLOPT_URL, $url);
 $res = curl_exec($curl);
 curl_close($curl);
 return $res;
 }
 private function get_php_file($token_name) {
 if(file_exists($token_name)) return false;
 return json_decode(file_get_contents($token_name), true);
 }
 private function set_php_file($token_name, $data) {
 $fp = fopen($token_name, "w");
 fwrite($fp, "<?php exit();?>" . json_encode($data));
 fclose($fp);
 }
}

这里再为大家推荐一款功能相似的在线工具供大家参考：

在线二维码解码识别工具：
http://tools.jb51.net/transcoding/trans_qrcode

希望本文所述对大家微信小程序开发有所帮助。