spring下利用ajax实现本地图片的上传

首先需要导入js:

//该js网上有很多版本，但有好些有错误
jQuery.extend({

createUploadIframe: function(id, uri)
{
    //create frame
    var frameId = 'jUploadFrame' + id;

    if(window.ActiveXObject) {
        var io = document.createElement('<iframe id="' + frameId + '" name="' + frameId + '" />');
        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 = $('<form  action="" method="POST" name="' + formId + '" id="' + formId + '" enctype="multipart/form-data"></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;
},
addOtherRequestsToForm: function(form,data)
{
    // add extra parameter
    var originalElement = $('<input type="hidden" name="" value="">');
    for (var key in data) {
        name = key;
        value = data[key];
        var cloneElement = originalElement.clone();
        cloneElement.attr({'name':name,'value':value});
        $(cloneElement).appendTo(form);
    }
    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);
    if ( s.data ) form = jQuery.addOtherRequestsToForm(form,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
            {
                $(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" )
    {
        // If you add mimetype in your response,
        // you have to delete the '<pre></pre>' tag.
        // The pre tag in Chrome has attribute, so have to use regex to remove
        var data = r.responseText;
        var rx = new RegExp("<pre.*?>(.*?)</pre>","i");
        var am = rx.exec(data);
        //this is the desired data extracted
        var data = (am) ? am[1] : "";    //the only submatch or empty
        eval( "data = " + data );
    }
    // evaluate scripts within html
    if ( type == "html" )
        jQuery("<div>").html(data).evalScripts();
    //alert($('param', data).each(function(){alert($(this).attr('value'));}));
    return data;
}

})

在input中定义type = “file”,在jsp中利用ajax将图片上传到本地指定的文件夹下：
var filePath;

    //通过ajax上传图片
    function ajaxFileUpload() {
        $.ajaxFileUpload({
            url: '<%=basePath%>/ablum/img',
            secureuri: false,
            fileElementId: 'fileToUpload',
            dataType: 'json',
            success: function (data, status) {
                /*alert("上传成功")*/
                if(data.flag == 2){
                    alert("上传的文件必须是图片");
                    return;
                }else if(data.flag == 0){
                    alert("上传出错");
                    return;
                }else if(data.flag == 3){
                    alert("图片不能大于1M");
                    return;
                }else{
                    alert("上传成功");
                    document.getElementById("upImg").style.display = "inline";
                    filePath = (JSON.stringify(data.filenamelist[0]));
                    filePath = filePath.substring(1, filePath.length - 1);
                }
            },
            error: function (data, status, e) {
                alert('上传出错');
            }
        })

        return false;

    }

该方法会请求ablum下的img方法：
/**
* 处理图片
*/
@RequestMapping("/img")
@ResponseBody
public Map Img(HttpServletRequest request) {
//获得编译后class文件的跟路径
String path = this.getClass().getClassLoader().getResource("/").getPath();
path = path.substring(0,path.length()-16)+"/images/ablumupload";
Map map = FileUpLoad.upload(request, path, “”, “ablum”);
return map;
}
controler层会调用类FileUpLoad中的静态方法upload对上传的图片进行处理，解析出图片的格式，大小等信息，并通过输入输入流将图片复制到本地指定的文件夹

本文地址：https://blog.csdn.net/qq_31118837/article/details/85987279