var freeOne=""; 
freeOne=$(".freePreviewOne").attr("data-url"); 
if(freeOne==null){ 
 //没有免费视频 
}else{ 
 $("#coursePicture").append("<a class='hide-650 fade5' "+ 
  "style='top:94px;left:150px;position:absolute;z-index:100; " + 
  " width: 180px;height: 60px;border: 2px solid white;" + 
  "display: block;color: white;text-decoration: none;" + 
  "letter-spacing: 1px;font-size: 16px;line-height: 20px;" + 
  "text-align:center;padding-top:18px;" + 
  "background-color: rgba(0, 0, 0, 0.44);" + 
  "-webkit-backface-visibility: hidden;-webkit-transition: all .3s ease-in-out;" + 
  "-moz-transition: all .3s ease-in-out;-ms-transition: all .3s ease-in-out;" + 
  "-o-transition: all .3s ease-in-out;" + 
  "border-radius: 10px;'"+ 
  "href='#modal' data-toggle='modal' "+ 
  "data-url='"+freeOne+"'> "+ 
  "<span class='contactus' style='font-size:26px;'>试 看</span> <span class='glyphicon glyphicon-play' style='font-size:20px;top:0;bottom:2px;'></span> </a>"
  );
}

<div class="es-row-wrap container-gap course-cover"> 
 <div class="row row-5-7 course-cover-heading"> 
 <div id="coursePicture" class="col-sm-5 picture hidden-xs" style="position: relative;"> 
 <#if course.coverImage?has_content> 
  <img src="${course.coverImage}" class="img-responsive" width="436px" height="245px" /> 
 <#else> 
  <img src="/resources/assets/img/default/course-large.png" class="img-responsive" />
 </#if> 
 </div> 
 </div>
</div> 

//在课程图片上放置按钮 
/* <a class="button hide-650 fade5" href="#modal" data-toggle="modal" data-url="/course/hyjgz2np/lesson/preview?lectureId=hyjgz2np0.49618492345325650.04212287697009742"> <span class="contactus"><strong>试看</strong></span> </a> 
*/ 
//$("#coursePicture").append("<a class='btn btn-sm btn-info' href='#' style='top:120px;left:180px;position:absolute;z-index:100;'>试看</a>"); 
var freeOne=""; 
freeOne=$(".freePreviewOne").attr("data-url"); 
if(freeOne==null){ 
 //没有免费视频 
}else{ 
 $("#coursePicture").append("<a class='freePreviewPicture hide-650 fade5' "+ 
  "href='#modal' data-toggle='modal' "+ 
  "data-url='"+freeOne+"'> "+ 
  "<span class='contactus' style='font-size:26px;'>试 看</span> <span class='glyphicon glyphicon-play' style='font-size:20px;top:0;bottom:2px;'></span> </a>" 
  ); 
}

<style> 
.freePreviewPicture{ 
 top:94px; 
 left:150px; 
 position:absolute; 
 z-index:100; 
 width: 180px; 
 height: 60px; 
 border: 2px solid white; 
 display: block; 
 color: white;text-decoration: none; 
 letter-spacing: 1px;font-size: 16px; 
 line-height: 20px; 
 text-align:center;padding-top:18px; 
 background-color: rgba(0, 0, 0, 0.44); 
 -webkit-backface-visibility: hidden; 
 -webkit-transition: all .3s ease-in-out; 
 -moz-transition: all .3s ease-in-out; 
 -ms-transition: all .3s ease-in-out; 
 -o-transition: all .3s ease-in-out; 
 border-radius: 10px; 
} 
</style> 
<div class="es-row-wrap container-gap course-cover"> 
 <div class="row row-5-7 course-cover-heading"> 
 <div id="coursePicture" class="col-sm-5 picture hidden-xs" style="position: relative;"> 
 <#if course.coverImage?has_content> 
  <img src="${course.coverImage}" class="img-responsive" width="436px" height="245px" /> 
 <#else> 
  <img src="/resources/assets/img/default/course-large.png" class="img-responsive" /> 
 </#if> 
 </div> 
 </div> 
</div>