JSP

jsp Click Picture Pop up File Upload Interface and Realize Detailed Explanation of Preview Example

jsp Click Picture Pop-up File Upload Interface and Implementation Preview Example Detailed Explanation

It took two days to ponder the function of picture preview

The task requirements are as follows:

1: There is a picture in the jsp page (pic_1)

2: Click on the picture to pop up an interface similar to Explorer

3: Preview at pic_1 after selecting a certain picture

I in IE8 test the following code, can achieve the above functions, not in other browsers test, if you know a variety of browser support methods, please comment, learn together, thank you.

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Insert title here</title>
<script type="text/javascript">
function tempClick(){

 /**
  *  Firefox browser realizes file uploading interface by clicking pictures
  * var a=document.createEvent("MouseEvents");
  * a.initEvent("click", true, true);
  * document.getElementById("upload_main_img").dispatchEvent(a);
  */

 //IE The browser realizes the file upload interface by clicking on the picture
 document.getElementById('main_img').click();   // Call main_img Adj. onclick Events
}

/**
 *  Preview Picture
 * @param obj
 * @returns {Boolean}
 */
function PreviewImg(obj) {

 var newPreview = document.getElementById("img_2");
 var imgPath = getPath(obj);
 alert(imgPath);
 if( !obj.value.match( /.jpg|.gif|.png|.bmp/i ) ){
  alert(" The picture format is wrong! ");
  return false;
 }

 newPreview.style.filter = "progid:DXImageTransform.Microsoft.AlphaImageLoader(sizingMethod=scale)";
 newPreview.filters.item("DXImageTransform.Microsoft.AlphaImageLoader").src = imgPath;
}

/**
 *  Get the absolute path of the picture
 * @param obj
 * @returns
 */
function getPath(obj){
 if(obj) {
  if(navigator.userAgent.indexOf("MSIE")>0) {
   obj.select();
   //IE Get the local path of the picture under
   return document.selection.createRange().text;
  } else if(isFirefox=navigator.userAgent.indexOf("Firefox")>0) {
    if (obj.files) { // Firefox What is obtained under is the data of the picture
    return files.item(0).getAsDataURL();
    }
    return obj.value;
   }
   return obj.value;
 }
}
</script>
</head>
<body>
<form>
<div><input type="file" style="position: absolute; filter: alpha(opacity = 0); opacity: 0; width: 30px;" size="1" id="main_img" name="main_img" onchange="PreviewImg(this)"></div>
<div id="img_2" style="width:133px;height:95px; cursor:pointer; background-image: url('Chrysanthemum.jpg');" onclick="tempClick()"></div>
</form>
</body>
</html>

Simply explain the code as follows:

input type= “file” This element I tried to hide style (style= “display: none”), so that I can’t get an absolute path, but fakepath. In order not to show it, let it be 100% transparent. Here is an div, id is img_2, and this div is the initial picture of the page. Click this picture to call the method in ES40type= “file” to realize this function.

Thank you for reading, hope to help everyone, thank you for your support to this site!