extjs如何完成下传文件功能——后台是java接收

extjs怎么完成上传文件功能——后台是java接收
extjs我完全不会啊，但是必须弄出来，就各位大虾帮帮我啊..... [code=myuploadform= new Ext.FormPanel({
                fileUpload: true,
                width: 500,
                autoHeight: true,
                bodyStyle: 'padding: 10px 10px 10px 10px;',
                labelWidth: 50,
                defaults: {
                    anchor: '95%',
                    allowBlank: false,
                    msgTarget: 'side'
                },
                items:[
                {
                    xtype: 'fileuploadfield',
                    id: 'filedata',
                    emptyText: 'Select a document to upload...',
                    fieldLabel: 'File',
                    buttonText: 'Browse'
                }],
                buttons: [{
                    text: 'Upload',
                    handler: function(){
                        if(myuploadform.getForm().isValid()){
                            form_action=1;
                            myuploadform.getForm().submit({
                                url: 'handleupload.php',
                                waitMsg: 'Uploading file...',