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Java implements drag and drop upload

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Release： 2016-11-11 10:48:54

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Java implements drag and drop upload

jsp上传前端代码

<%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>  
<!DOCTYPE html>  
<html>  
<head>  
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">  
<title></title>  
<style type="text/css">  
* {  
    padding: 0px;  
    margin: 0px;  
}  
   
body {  
    background: #394E48;  
    font-size: 14px;  
    font-family: "微软雅黑";  
}  
   
.title {  
    text-align: center;  
    color: #fff;  
    margin-top: 50px;  
}  
   
.demo {  
    width: 900px;  
    height: 140px;  
    margin: 50px auto;  
}  
   
.drag-area {  
    width: 100%;  
    height: 100px;  
    border: 3px dashed #fff;  
    text-align: center;  
    line-height: 100px;  
    color: #fff;  
    font-size: 36px;  
    font-weight: 700;  
}  
   
}  
.preview div {  
    width: 195px;  
    overflow: hidden;  
    border: 1px dashed silver;  
    margin-top: 10px;  
    float: left;  
    padding: 9px;  
    text-align: center;  
    height: 168px;  
}  
   
.preview img {  
    width: 80px;  
    height: 80px;  
}  
</style>  
</head>  
<body>  
    <h1 class="title">小夜的传说最新力作！Java实现拖拽上传！！</h1>  
     <div class="demo">  
        <div class="drag-area" id="upload-area">  
            将图片拖拽到这里  
        </div>  
        <!-- 图片预览 -->  
        <div id="preview" class="preview"></div>  
     </div>  
</body>  
<script type="text/javascript">  
    //1、文件上传HTML5 通过drag把文件拖拽到浏览器的默认事件覆盖  
    //文件离开  
    document.ondragleave=function(e){  
    e.preventDefault();  
        console.info("文件离开执行了我！！");  
    };  
    //鼠标松开文件  
    document.ondrop=function(e){  
    e.preventDefault();  
        console.info("松开以后执行了我！");  
    };  
    //鼠标移动文件  
    document.ondragover=function(e){  
    e.preventDefault();  
        console.info("文件移动以后执行了我！");  
    };  
       
    function tm_upload(){  
        var img1="";  
        var uploadArea=document.getElementById("upload-area");  
        //2、通过HTML5拖拽事件，ondrop，然后通过拖动区域监听浏览器的drop事件达到文件上传的目的  
        uploadArea.addEventListener("drop", function(e){  
            e.preventDefault();  
            //3、从事件event中获取拖拽到浏览器的文件信息  
            var fileList=e.dataTransfer.files;  
            for(var i=0;i<fileList.length;i++){  
                //此处判断只能上传图片  
                if(fileList[i].type.indexOf("image")!=0){  
                    alert("请上传图片");  
                    return;               
                }  
                //图片预览  这一步需要判断是什么浏览器  大家自己判断吧  
                /*************************************/ 
                img1=window.URL.createObjectURL(fileList[i]);  
                /*************************************/ 
                var str="<div><img  src=&#39;"+img1+"&#39;/ alt="Java implements drag and drop upload" ><p>"+fileList[i].name+"</p></div>";  
                document.getElementById("preview").innerHTML +=str;  
                   
                var fileName=fileList[i].name;  
                console.info(fileName);  
                var fileSize=fileList[i].size;  
                console.info(fileSize);  
                //4、通过XMLHttpRequest上传文件到服务器  就是一个ajax请求  
                var xhr=new XMLHttpRequest();  
                //5、这里需要先写好一个data.jsp的上传文件，当然，你写成servlet或者是action都可以  
                xhr.open("post","data.jsp",true);  
                xhr.setRequestHeader("X-Request-Width", "XMLHttpRequest");  
                //6、通过HTML5 FormData动态设置表单元素  
                var formData=new FormData();//动态给表单赋值，传递二进制文件  
                //其实就相当于<input type="file" name="file"/>  
                formData.append("doc",fileList[i]);  
                xhr.send(formData);  
            }  
        });  
    }  
    //直接调用  
    tm_upload();  
</script>  
</html>

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ok，编写完前台代码，在写后台，如下:

<%@page import="java.util.UUID"%>  
<%@page import="org.apache.commons.fileupload.FileItem"%>  
<%@page import="java.util.Iterator"%>  
<%@page import="java.util.List"%>  
<%@page import="org.apache.commons.fileupload.servlet.ServletFileUpload"%>  
<%@page import="org.apache.commons.fileupload.disk.DiskFileItemFactory"%>  
<%@page import="org.apache.commons.fileupload.FileItemFactory"%>  
<%@page import="java.io.File"%>  
<%@ page language="java" contentType="text/html; charset=UTF-8" 
    pageEncoding="UTF-8"%>  
<%  
/*  
1、文件上传:  
   
*/ 
request.setCharacterEncoding("utf-8");  
response.setCharacterEncoding("utf-8");  
//获取文件路径  
String strPath=request.getRealPath("/")+"/upload";  
File file =new File(strPath);  
if(!file.exists())file.mkdirs();  
FileItemFactory factory=new DiskFileItemFactory();  
ServletFileUpload upload=new ServletFileUpload(factory);  
//从请求对象中获取文件信息  
List items= upload.parseRequest(request);  
if(items!=null){  
    for(int i=0;i<items.size();i++){  
        Iterator iterator=items.iterator();  
        while(iterator.hasNext()){  
        FileItem item=(FileItem)iterator.next();  
        if(item.isFormField()){  
            continue;  
        }else{  
            String fileName=item.getName();  
            Long fileSize=item.getSize();  
            int pos=fileName.indexOf(".");  
            String ext=fileName.substring(pos,fileName.length());     
            fileName=UUID.randomUUID().toString()+ext;  
            File saveFile=new File(strPath,fileName);  
            item.write(saveFile);  
         }  
        }  
    }  
}  
 %>

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