JavaScript实现多张图片上传功能

今天闲着没事，把之前的多张图片上传代码整理了下。

页面主要代码：

 <div class="upBox upBox2">
     <div class="d1">
         <a class="redA1 rightA" href="javascript:choosePhotos();" id="continue_add_button" style="display:none;">继续添加</a>
     </div>
     <div class="d2" id="add_photo_button">
         <a href="javascript:choosePhotos();" class="blueA1">从电脑上传照片</a>
         <p class="p1">注：支持JPG格式多张上传，按住Ctrl或Shift选择图片，一次最多可上传150张照片</p>
     </div>
     <input type="file" id="upload" accept="image/jpeg" multiple="multiple" style="display:none;" />
     <canvas id="myCanvas" style="display:none;"></canvas>
     <div class="d3">
         <ul class="ul1 clearfix" id="local_upload_div">

         </ul>
     </div>
 </div>

js部分主要代码，其实不用html5的画布也行，不过貌似用画布页面加载比直接预览图较快。

具体上传代码没写，和单张上传是一样的，需要的朋友可以去我的另一篇写单张上传的博客里看一下：JavaScript实现单张图片上传功能

 //准备上传的模板
 var mb_upload = "<li id=\"up_li_INDEX\">"+
                     "<div>"+
                         "<div class=\"imgD\">" +
                             "<img id=\"up_img_INDEX\" src=\"/img/upload/morenI.png\" >"+
                         "</div>" +
                         "<p class=\"jdP\" id=\"up_p_INDEX\">" +
                             "<img class=\"i1\" src=\"/img/upload/loading.gif\">"+
                             "准备上传"+
                         "</p>" +
                     "</div>"+
                 "</li>";

 $(function(){
     //文件域改变时触发
     $('#upload').change(function (evt) {
           fileChange(evt);
     });
 });

 //触发文件域
 function choosePhotos(){
     $("#upload").click();
 }

 //文件域改变时触发
 function fileChange(evt){
     var files = evt.target.files;
     if(files.length == 0)return;
     //上传页面已有照片数量
     var up_page_num = $("#local_upload_div li").length;

     $("#add_photo_button").hide();
     $("#continue_add_button").show();

     layer.msg('照片加载中', {icon: 16});

     for(var m=0; m<files.length; m++){
         var f = files[m];
         console.log("type="+f.type+" name="+f.name+" length="+f.size);
         addPhoto(m+1+up_page_num);
     }
     getImagesInfo(files,0,up_page_num);

 }

 //页面添加等待上传的预显示图片
 function addPhoto(i){
     var segment = mb_upload;
     segment = segment.replace(/INDEX/g,i);
     $("#local_upload_div").append(segment);
 }

 //获取到照片信息并在页面添加预览图
 var getImagesInfo = function(files,a,up_page_num){

     if(files.length > a){

         usUploading = true;

         var f = files[a];

         ///var type = f.type;
         //获取容器
         var c = document.getElementById("myCanvas");
         //获取画布对象
         var cxt = c.getContext("2d");

         var reader = new FileReader();

         var name = f.name;//完整照片名称，带格式

         //异步方法，文件读取完毕才执行
         reader.onload = function(e){
             //图片的读取结果
             var dataImg = e.target.result;
             var img = new Image();
             //异步方法
             img.onload = function(){
                 var ratio = img.width/img.height;
                 var h,w;
                 //等比例压缩宽和高
                 if(ratio>1){
                     w = 110;
                     h = w*img.height/img.width;
                 }else{
                     h = 110;
                     w = h*img.width/img.height;
                 }
                 //容器设置宽和高
                 c.width = w;
                 c.height = h;
                 //清空容器
                 cxt.clearRect(0, 0, w, h);
                 //开始作画
                 cxt.drawImage(img,0,0,w,h);
                 //获取容器中画的url
                 var compressed = c.toDataURL("image/jpeg");   

                 //将预览图插入上传页面
                 $("#up_img_"+(a+1+up_page_num)).attr("src",compressed);
                 $("#up_img_"+(a+1+up_page_num)).show("slow");

                 syncUpload(files,dataImg,a,name,up_page_num);
             };
             //将图片的读取结果赋到img对象的src属性上
             img.src = dataImg;
         };
         //将图片读取为URL数据:base64编码
         reader.readAsDataURL(f);
     }
 }

 //原图上传
 var syncUpload = function(files,imgStr,index,name,up_page_num){

     sleep(1000);//延时1s，模拟ajax，O(∩_∩)O哈哈~

     //这里就是和单张上传逻辑一样了，只不过在上传成功后再次调用上面的方法，具体上传的方法就不写了
     $("#up_p_"+(index+1+up_page_num)).html("<img class=\"i1\" src=\"/img/upload/duihao2.png\">"+
                                             "上传成功"+
                                             "<a href=\"javascript:void(0);\" class=\"right\"><img class=\"i2\" src=\"/img/upload/shanI.gif\"></a>");

     getImagesInfo(files,++index,up_page_num);

 };

 //设置延时函数
 function sleep(numberMillis) {
     var now = new Date();
     var exitTime = now.getTime() + numberMillis;
     while (true) {
         now = new Date();
         if (now.getTime() > exitTime)return;
     }
 }

看看基本效果O(∩_∩)O：