ajax实现图片的回显功能
前端页面
给文件上传域绑定一个改变事件
图片介绍
选择图片后通过ajax发送请求到服务端，把图片进行存储并且返回json数据，使得图片回显
这里采用的$.ajaxFileUpload是一个命名为ajaxfileupload.js需要引入到js包下面，直接赋值下面代码即可
jQuery.extend({
createUploadIframe: function(id, uri)
{
//create frame
var frameId = 'jUploadFrame' + id;
if(window.ActiveXObject) {
var io = document.createElement('');
if(typeof uri== 'boolean'){
io.src = 'javascript:false';
}
else if(typeof uri== 'string'){
io.src = uri;
}
}
else {
var io = document.createElement('iframe');
io.id = frameId;
io.name = frameId;
}
io.style.position = 'absolute';
io.style.top = '-1000px';
io.style.left = '-1000px';
document.body.appendChild(io);
return io
},
createUploadForm: function(id, fileElementId)
{
//create form
var formId = 'jUploadForm' + id;
var fileId = 'jUploadFile' + id;
var form = $('');
var oldElement = $('#' + fileElementId);
var newElement = $(oldElement).clone();
$(oldElement).attr('id', fileId);
$(oldElement).before(newElement);
$(oldElement).appendTo(form);
//set attributes
$(form).css('position', 'absolute');
$(form).css('top', '-1200px');
$(form).css('left', '-1200px');
$(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 = s.fileElementId;
var form = jQuery.createUploadForm(id, s.fileElementId);
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
{
$(io).remove();
$(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 io = $('#' + frameId);
var form = $('#' + formId);
$(form).attr('action', s.url);
$(form).attr('method', 'POST');
$(form).attr('target', frameId);
if(form.encoding)
{
form.encoding = 'multipart/form-data';
}
else
{
form.enctype = 'multipart/form-data';
}
$(form).submit();
} catch(e)
{
jQuery.handleError(s, xml, null, e);
}
if(window.attachEvent){
document.getElementById(frameId).attachEvent('onload', uploadCallback);
}
else{
document.getElementById(frameId).addEventListener('load', uploadCallback, false);
}
return {abort: function () {}};
},
uploadHttpData: function( r, type ) {
var data = !type;
data = type == "xml" || data ? r.responseXML : r.responseText;
// If the type is "script", eval it in global context
if ( type == "script" )
jQuery.globalEval( data );
// Get the JavaScript object, if JSON is used.
if ( type == "json" )
eval( "data = " + data );
// evaluate scripts within html
if ( type == "html" )
jQuery("").html(data).evalScripts();
//alert($('param', data).each(function(){alert($(this).attr('value'));}));
return data;
}
})
服务端
主要采用了spring mvc框架，并且利用了多部件解析器
//异步ajax的图片回显功能
@ResponseBody
@RequestMapping("/ajaxImg.action")
public Object ajaximg(MultipartFile pimage,HttpServletRequest request){
//提取生成文件名UUID+文件名后缀 保证图片可以重复
String saveFileName= FileNameUtil.getUUIDFileName()+FileNameUtil.getFileType(pimage.getOriginalFilename());
//得到项目中图片的存储路径
String path = request.getServletContext().getRealPath("/image_big");
//转存文件
try {
pimage.transferTo(new File(path+File.separator+saveFileName));
} catch (IOException e) {
e.printStackTrace();
}
//返回一个json对象
JSONObject object = new JSONObject();
object.put("imgurl",saveFileName);
return object.toString();
}
这里利用到了一个文件名的工具类，主要是生成一个随机的文件名和对文件名后缀的截取
public class FileNameUtil {
//根据UUID生成文件名
public static String getUUIDFileName() {
UUID uuid = UUID.randomUUID();
return uuid.toString().replace("-", "");
}
//从请求头中提取文件名和类型
public static String getRealFileName(String context) {
// Content-Disposition: form-data; name="myfile"; filename="a_left.jpg"
int index = context.lastIndexOf("=");
String filename = context.substring(index + 2, context.length() - 1);
return filename;
}
//根据给定的文件名和后缀截取文件名
public static String getFileType(String fileName){
//9527s.jpg
int index = fileName.lastIndexOf(".");
return fileName.substring(index);
}
}
另外json转换工具用的是下面的，其中要注意要返回json数据格式时必须要用toString方法
org.json
json
20140107
最终效果展示
