JFinal使用ajaxfileupload实现图片上传及预览

本文实例为大家分享了JFinal使用ajaxfileupload实现图片上传预览的具体代码，供大家参考，具体内容如下

1.前端jsp页面核心代码

<script type="text/javascript" src="<％=request.getContextPath() ％>/js/jquery.min.js"></script>
<script type="text/javascript" src="<％=request.getContextPath() ％>/media/ajaxupload/ajaxfileupload.js"></script>

<input type="file" class="upload" name="file" id="upfile" onchange="ajaxFileUpload('upfile')"/>
<!--用于预览图片-->
<img src="<c:if test="${banner.img!=null}"><％=request.getContextPath() ％>/media/file/${banner.img}</c:if>" style="width:300px;height:100px;" id="imgsrc"/>
<!--存放图片路径,提交页面时传给后台的值-->
<input id='imgurl' type='hidden' name="imgurl" style="height:30px;width:100％" value='${banner.img}'/>

function ajaxFileUpload(fileEid, paramdata){
if(typeof(paramdata)=='undefined') paramdata = {};
var $file=$('#'+fileEid).val();
if($file=='') {alert("请先选择对应的上传文件，谢谢"); return;}

$.ajaxFileUpload({
url:'<％=request.getContextPath()％>/banner/uploadpic',
secureuri:false,
fileElementId:fileEid,
dataType: 'text',
data:paramdata,
success: function (result){
 var result = result.substring(result.indexOf("{"),result.indexOf("}")+1);
 result = eval("("+result+")");

if(result.t==1){
 $("#imgsrc").attr("src","<％=request.getContextPath() ％>/media/file/"+result.msg);
 $("#imgurl").val(result.msg);
 }else{
 alert("上传失败");
 }
}
});
}

2.后台核心代码

public void uploadpic(){
UploadFile upfile = getFile();//JFinal规定getFile()必须最先执行
File file = upfile.getFile();
String filename = file.getName();
String delfilename = filename;
if(filename!=null && !filename.equals("")){
filename = new SimpleDateFormat("yyyyMMddkkmmss").format(new Date())+filename;
/**
 * 新保存的位置
 */
String path = getRequest().getSession().getServletContext()
 .getRealPath("/");
String newPath = "/media/file/";//自定义目录 用于存放图片
/**
 * 没有则新建目录
 */
File floder = new File(path + newPath);
if (!floder.exists()) {
 floder.mkdirs();
}
/**
 * 保存新文件
 */
FileInputStream fis = null;
FileOutputStream fos = null;
try{
 File savePath = new File(path + newPath + filename);
 if(!savePath.isDirectory()) savePath.createNewFile();
 fis = new FileInputStream(file);
 fos = new FileOutputStream(savePath);
 byte[] bt = new byte[300];
 while (fis.read(bt, 0, 300) != -1) {
 fos.write(bt, 0, 300);
 }
}catch(Exception e){
 e.printStackTrace();
}finally{
 try{
 if(null!=fis) fis.close();
 if(null!=fos) fos.close();
 }catch(Exception e){
 e.printStackTrace();
 }
}

/**
 * 删除原图片，JFinal默认上传文件路径为 /upload（自动创建）
 */
File delFile = new File(path+"/upload/"+delfilename);
if(delFile.exists()){
 delFile.delete();
}
setAttr("msg",filename);
setAttr("t",1);
}else{
setAttr("t",0);
}
renderJson();
}

附：ajaxfileupload.js代码

jQuery.extend({
createUploadIframe: function(id, uri) {
//create frame
var frameId = 'jUploadFrame' + id;
var iframeHtml = '<iframe id="' + frameId + '" name="' + frameId + '" style="position:absolute; top:-9999px; left:-9999px"';
if(window.ActiveXObject) {
 if(typeof uri== 'boolean'){
 iframeHtml += ' src="' + 'javascript:false' + '"';
 } else if(typeof uri== 'string'){
 iframeHtml += ' src="' + uri + '"';
 }
}
iframeHtml += ' />';
jQuery(iframeHtml).appendTo(document.body);
return jQuery('#' + frameId).get(0);
},
createUploadForm: function(id, fileElementId, data) {
//create form
var formId = 'jUploadForm' + id;
var fileId = 'jUploadFile' + id;
var form = jQuery('<form action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></form>');
if(data) {
 for(var i in data) {
 jQuery('<input type="hidden" name="' + i + '" value="' + data[i] + '" />').appendTo(form);
 }
}
var oldElement = jQuery('#' + fileElementId);
var newElement = jQuery(oldElement).clone();
jQuery(oldElement).attr('id', fileId);
jQuery(oldElement).before(newElement);
jQuery(oldElement).appendTo(form);

//set attributes
jQuery(form).css('position', 'absolute');
jQuery(form).css('top', '-1200px');
jQuery(form).css('left', '-1200px');
jQuery(form).appendTo('body');
return form;
},

ajaxFileUpload: function(s) {
// TODO introduce global settings, allowing the client to modify them for all requests, not only timeout
s = jQuery.extend({}, jQuery.ajaxSettings, s);
var id = new Date().getTime()
var form = jQuery.createUploadForm(id, s.fileElementId, (typeof(s.data)=='undefined'?false:s.data));
var io = jQuery.createUploadIframe(id, s.secureuri);
var frameId = 'jUploadFrame' + id;
var formId = 'jUploadForm' + id;
// Watch for a new set of requests
if ( s.global && ! jQuery.active++ )
{
 jQuery.event.trigger( "ajaxStart" );
}  
var requestDone = false;
// Create the request object
var xml = {}
if ( s.global )
 jQuery.event.trigger("ajaxSend", [xml, s]);
// Wait for a response to come back
var uploadCallback = function(isTimeout)
{  
 var io = document.getElementById(frameId);
 try {
 if(io.contentWindow) {
  xml.responseText = io.contentWindow.document.body?io.contentWindow.document.body.innerHTML:null;
  xml.responseXML = io.contentWindow.document.XMLDocument?io.contentWindow.document.XMLDocument:io.contentWindow.document;
 } else if(io.contentDocument) {
  xml.responseText = io.contentDocument.document.body?io.contentDocument.document.body.innerHTML:null;
  xml.responseXML = io.contentDocument.document.XMLDocument?io.contentDocument.document.XMLDocument:io.contentDocument.document;
 }
 } catch(e) {
 jQuery.handleError(s, xml, null, e);
 }
 if ( xml || isTimeout == "timeout") {
 requestDone = true;
 var status;
 try {
  status = isTimeout != "timeout" ? "success" : "error";
  // Make sure that the request was successful or notmodified
  if ( status != "error" ) {
  // process the data (runs the xml through httpData regardless of callback)
  var data = jQuery.uploadHttpData( xml, s.dataType );
  // If a local callback was specified, fire it and pass it the data
  if ( s.success )
   s.success( data, status );

// Fire the global callback
  if( s.global )
   jQuery.event.trigger( "ajaxSuccess", [xml, s] );
  } else
  jQuery.handleError(s, xml, status);
 } catch(e) {
  status = "error";
  jQuery.handleError(s, xml, status, e);
 }

// The request was completed
 if( s.global )
  jQuery.event.trigger( "ajaxComplete", [xml, s] );

// Handle the global AJAX counter
 if ( s.global && ! --jQuery.active )
  jQuery.event.trigger( "ajaxStop" );

// Process result
 if ( s.complete )
  s.complete(xml, status);

jQuery(io).unbind()

setTimeout(function() {
    try {
     jQuery(io).remove();
     jQuery(form).remove();
    } catch(e) {
     jQuery.handleError(s, xml, null, e);
    }
    }, 100)
 xml = null
 }
}
// Timeout checker
if ( s.timeout > 0 )
{
 setTimeout(function(){
 // Check to see if the request is still happening
 if( !requestDone ) uploadCallback( "timeout" );
 }, s.timeout);
}
try
{

var form = jQuery('#' + formId);
 jQuery(form).attr('action', s.url);
 jQuery(form).attr('method', 'POST');
 jQuery(form).attr('target', frameId);
 if(form.encoding) {
 jQuery(form).attr('encoding', 'multipart/form-data');
 } else {
 jQuery(form).attr('enctype', 'multipart/form-data');
 }  
 jQuery(form).submit();
} catch(e) {
 jQuery.handleError(s, xml, null, e);
}

jQuery('#' + frameId).load(uploadCallback);
return {abort: function () {}};
},

uploadHttpData: function( r, type ) {
var data = !type;
data = type == "xml" || data ? r.responseXML : r.responseText;
// If the type is "script", eval it in global context
if ( type == "script" )
 jQuery.globalEval( data );
// Get the JavaScript object, if JSON is used.
if ( type == "json" )
 eval( "data = " + data );
// evaluate scripts within html
if ( type == "html" )
 jQuery("<div>").html(data).evalScripts();
return data;
}
})

来源：https://blog.csdn.net/z834410038/article/details/54598747