分离与继承的思想实现图片上传后的预览功能：ImageUploadView

<div class="holy-layout-am appForm-group appForm-group-img-upload clearfix">
<label class="holy-layout-al">法人身份证电子版</label>
<div class="holy-layout-m">
<input id="legalPersonIDPic-input" name="legalPersonIDPic" class="form-control form-field"
type="hidden">
<ul id="legalPersonIDPic-view" class="image-upload-view clearfix">
<li class="view-item-add"><a class="view-act-add" href="javascript:;" title="点击上传">+</a>
</li>
</ul>
<p class="img-upload-msg">
请确保图片清晰，文字可辨
<a href="#" title="查看示例"><i class="fa fa-question-circle"></i> 查看示例</a>
</p>
</div>
</div>

var DEFAULTS = {
data: [], //要展示的数据列表，列表元素必须是object类型的，如[{url: 'xxx.png'},{url: 'yyyy.png'}]
sizeLimit: 0, //用来限制BaseView中的展示的元素个数，为0表示不限制
readonly: false, //用来控制BaseView中的元素是否允许增加和删除
onBeforeRender: $.noop, //对应render.before事件，在render方法调用前触发
onRender: $.noop, //对应render.after事件，在render方法调用后触发
onBeforeAppend: $.noop, //对应append.before事件，在append方法调用前触发
onAppend: $.noop, //对应append.after事件，在append方法调用后触发
onBeforeDelItem: $.noop, //对应delItem.before事件，在delItem方法调用前触发
onDelItem: $.noop //对应delItem.after事件，在delItem方法调用后触发
};

init: function (element, options) {
//通过this.base调用父类EventBase的init方法
this.base(element);
//实例属性
var opts = this.options = this.getOptions(options);
this.data = resolveData(opts.data);
delete opts.data;
this.sizeLimit = opts.sizeLimit;
this.readOnly = opts.readOnly;
//绑定事件
this.on('render.before', $.proxy(opts.onBeforeRender, this));
this.on('render.after', $.proxy(opts.onRender, this));
this.on('append.before', $.proxy(opts.onBeforeAppend, this));
this.on('append.after', $.proxy(opts.onAppend, this));
this.on('delItem.before', $.proxy(opts.onBeforeDelItem, this));
this.on('delItem.after', $.proxy(opts.onDelItem, this));
},

render: function () {
/**
* render是一个模板，子类不需要重写render方法，只需要重写_render方法
* 当调用子类的render方法时调用的是父类的render方法
* 但是执行到_render方法时，调用的是子类的_render方法
* 这样就能把before跟after事件的触发操作统一起来
*/
var e;
this.trigger(e = $.Event('render.before'));
if (e.isDefaultPrevented()) return;
this._render();
this.trigger($.Event('render.after'));
},
//子类需实现_Render方法
_render: function () {
},
append: function (item) {
var e;
if (!item) return;
item = resolveDataItem(item);
this.trigger(e = $.Event('append.before'), item);
if (e.isDefaultPrevented()) return;
this.data.push(item);
this._append(item);
this.trigger($.Event('append.after'), item);
},
//子类需实现_append方法
_append: function (data) {
},
delItem: function (uuid) {
var e, item = this.getDataItem(uuid);
if (!item) return;
this.trigger(e = $.Event('delItem.before'), item);
if (e.isDefaultPrevented()) return;
this.data.splice(this.getDataItemIndex(uuid), 1);
this._delItem(item);
this.trigger($.Event('delItem.after'), item);
},
//子类需实现_delItem方法
_delItem: function (data) {
}

define(function (require, exports, module) {
var $ = require('jquery');
var Class = require('mod/class');
var EventBase = require('mod/eventBase');
var DEFAULTS = {
data: [], //要展示的数据列表，列表元素必须是object类型的，如[{url: 'xxx.png'},{url: 'yyyy.png'}]
sizeLimit: 0, //用来限制BaseView中的展示的元素个数，为0表示不限制
readonly: false, //用来控制BaseView中的元素是否允许增加和删除
onBeforeRender: $.noop, //对应render.before事件，在render方法调用前触发
onRender: $.noop, //对应render.after事件，在render方法调用后触发
onBeforeAppend: $.noop, //对应append.before事件，在append方法调用前触发
onAppend: $.noop, //对应append.after事件，在append方法调用后触发
onBeforeDelItem: $.noop, //对应delItem.before事件，在delItem方法调用前触发
onDelItem: $.noop //对应delItem.after事件，在delItem方法调用后触发
};
/**
* 数据处理，给data的每条记录都添加一个_uuid的属性，方便查找
*/
function resolveData(data) {
var time = new Date().getTime();
return $.map(data, function (d) {
return resolveDataItem(d, time);
});
}
function resolveDataItem(data, time) {
time = time || new Date().getTime();
data._uuid = '_uuid' + time + Math.floor(Math.random() * 100000);
return data;
}
var FileUploadBaseView = Class({
instanceMembers: {
init: function (element, options) {
//通过this.base调用父类EventBase的init方法
this.base(element);
//实例属性
var opts = this.options = this.getOptions(options);
this.data = resolveData(opts.data);
delete opts.data;
this.sizeLimit = opts.sizeLimit;
this.readOnly = opts.readOnly;
//绑定事件
this.on('render.before', $.proxy(opts.onBeforeRender, this));
this.on('render.after', $.proxy(opts.onRender, this));
this.on('append.before', $.proxy(opts.onBeforeAppend, this));
this.on('append.after', $.proxy(opts.onAppend, this));
this.on('delItem.before', $.proxy(opts.onBeforeDelItem, this));
this.on('delItem.after', $.proxy(opts.onDelItem, this));
},
getOptions: function (options) {
return $.extend({}, this.getDefaults(), options);
},
getDefaults: function () {
return DEFAULTS;
},
getDataItem: function (uuid) {
//根据uuid获取dateItem
return this.data.filter(function (item) {
return item._uuid === uuid;
})[0];
},
getDataItemIndex: function (uuid) {
var ret;
this.data.forEach(function (item, i) {
item._uuid === uuid && (ret = i);
});
return ret;
},
render: function () {
/**
* render是一个模板，子类不需要重写render方法，只需要重写_render方法
* 当调用子类的render方法时调用的是父类的render方法
* 但是执行到_render方法时，调用的是子类的_render方法
* 这样就能把before跟after事件的触发操作统一起来
*/
var e;
this.trigger(e = $.Event('render.before'));
if (e.isDefaultPrevented()) return;
this._render();
this.trigger($.Event('render.after'));
},
//子类需实现_Render方法
_render: function () {
},
append: function (item) {
var e;
if (!item) return;
item = resolveDataItem(item);
this.trigger(e = $.Event('append.before'), item);
if (e.isDefaultPrevented()) return;
this.data.push(item);
this._append(item);
this.trigger($.Event('append.after'), item);
},
//子类需实现_append方法
_append: function (data) {
},
delItem: function (uuid) {
var e, item = this.getDataItem(uuid);
if (!item) return;
this.trigger(e = $.Event('delItem.before'), item);
if (e.isDefaultPrevented()) return;
this.data.splice(this.getDataItemIndex(uuid), 1);
this._delItem(item);
this.trigger($.Event('delItem.after'), item);
},
//子类需实现_delItem方法
_delItem: function (data) {
}
},
extend: EventBase,
staticMembers: {
DEFAULTS: DEFAULTS
}
});
return FileUploadBaseView;
});

//继承并扩展父类的默认DEFAULTS
var DEFAULTS = $.extend({}, FileUploadBaseView.DEFAULTS, {
onAppendClick: $.noop //点击上传按钮时候的回调
});

define(function (require, exports, module) {
var $ = require('jquery');
var Class = require('mod/class');
var FileUploadBaseView = require('mod/fileUploadBaseView');
//继承并扩展父类的默认DEFAULTS
var DEFAULTS = $.extend({}, FileUploadBaseView.DEFAULTS, {
onAppendClick: $.noop //点击上传按钮时候的回调
});
var ImageUploadView = Class({
instanceMembers: {
init: function (element, options) {
var $element = this.$element = $(element);
var opts = this.getOptions(options);
//调用父类的init方法完成options获取，data解析以及通用事件的监听处理
this.base(this.$element, options);
//添加上传和删除的监听器及触发处理
if (!this.readOnly) {
var that = this;
that.on('appendClick', $.proxy(opts.onAppendClick, this));
$element.on('click.append', '.view-act-add', function (e) {
e.preventDefault();
that.trigger('appendClick');
});
$element.on('click.remove', '.view-act-del', function (e) {
var $this = $(e.currentTarget);
that.delItem($this.data('uuid'));
e.preventDefault();
});
}
this.render();
},
getDefaults: function () {
return DEFAULTS;
},
_setItemAddHtml: function () {
this.$element.prepend($('<li class="view-item-add"><a class="view-act-add" href="javascript:;" title="点击上传">+</a></li>'));
},
_clearItemAddHtml: function ($itemAddLi) {
$itemAddLi.remove();
},
_render: function () {
var html = [], that = this;
//如果不是只读的状态，并且还没有达到上传限制的话，就添加上传按钮
if (!(this.readOnly || (this.sizeLimit && this.sizeLimit <= this.data.length))) {
this._setItemAddHtml();
}
this.data.forEach(function (item) {
html.push(that._getItemRenderHtml(item))
});
this.$element.append($(html.join('')));
},
_getItemRenderHtml: function (item) {
return [
'<li id="',
item._uuid,
'"><a class="view-act-preview" href="javascript:;"><img alt="" src="',
item.url,
'">',
this.readOnly ? '' : '<span class="view-act-del" data-uuid="',
item._uuid,
'">删除</span>',
'</a></li>'
].join('');
},
_dealWithSizeLimit: function () {
if (this.sizeLimit) {
var $itemAddLi = this.$element.find('li.view-item-add');
//如果已经达到上传限制的话，就移除上传按钮
if (this.sizeLimit && this.sizeLimit <= this.data.length && $itemAddLi.length) {
this._clearItemAddHtml($itemAddLi);
} else if (!$itemAddLi.length) {
this._setItemAddHtml();
}
}
},
_append: function (data) {
this.$element.append($(this._getItemRenderHtml(data)));
this._dealWithSizeLimit();
},
_delItem: function (data) {
$('#' + data._uuid).remove();
this._dealWithSizeLimit();
}
},
extend: FileUploadBaseView
});
return ImageUploadView;
});

define(function(require, exports, module) {
return function() {
var imgList = ['../img/1.jpg','../img/2.jpg','../img/3.jpg','../img/4.jpg'], i = 0;
var that = this;
that.onSuccess = function(uploadValue){}
this.openChooseFileWin = function(){
setTimeout(function(){
that.onSuccess(imgList[i++]);
if(i == imgList.length) {
i = 0;
}
},1000);
}
}
});

define(function (require, exports, module) {
var $ = require('jquery');
var ImageUploadView = require('mod/imageUploadView');
var FileUploader = require('mod/fileUploader');//这是用异步任务模拟的文件上传组件
//$legalPersonIDPic，用来存储已上传的文件信息，上传组件上传成功之后以及ImageUploadView组件删除某个item之后会对$legalPersonIDPic的值产生影响
var $legalPersonIDPic = $('#legalPersonIDPic-input'),
data = JSON.parse($legalPersonIDPic.val() || '[]');//data是初始值，比如当前页面有可能是从数据库加载的，需要用ImageUploadView组件呈现出来
//在文件上传成功之后，将刚上传的文件保存到$legalPersonIDPic的value中
//$legalPersonIDPic以json字符串的形式存储
var appendImageInputValue = function ($input, item) {
var value = JSON.parse($input.val() || '[]');
value.push(item);
$input.val(JSON.stringify(value));
};
//当调用ImageUploadView组件删除某个item之后，要同步把$legalPersonIDPic中已存储的信息清掉
var removeImageInputValue = function ($input, uuid) {
var value = JSON.parse($input.val() || '[]'), index;
value.forEach(function (item, i) {
if (item._uuid === uuid) {
index = i;
}
});
value.splice(index, 1);
$input.val(JSON.stringify(value));
};
var fileUploader = new FileUploader();
fileUploader.onSuccess = function (uploadValue) {
var item = {url: uploadValue};
legalPersonIDPicView.append(item);
appendImageInputValue($legalPersonIDPic, item);
};
var legalPersonIDPicView = new ImageUploadView('#legalPersonIDPic-view', {
data: data,
sizeLimit: 4,
onAppendClick: function () {
//打开选择文件的窗口
fileUploader.openChooseFileWin();
},
onDelItem: function (data) {
removeImageInputValue($legalPersonIDPic, data._uuid);
}
});
});