☆☆☆Dojo中define和declare的结合使用

在原生的js中是不可以创建类的，没有class这个关键字，但是在dojo中，dojo自定义了一个模块叫做dojo/_base/declare，用这个模块我们可以创建自己的类，实现面向对象编程。

单继承例子：

define(["dojo/_base/declare"],function(declare){
    return declare("namespace.Person",null,{
        name:null,
        age:null,
        constructor: function(args){
            declare.safeMixin(this,args);
        },
        toString:function(){
            return this.name+":"+this.age
        }
    })
})
//调用自定义的类：
require(["js/person"], function(Person) {
    var p=new Person({
    name:"wpx",
    age:20
    });
    alert(p.toString())
});

多继承例子:

define(["dojo/_base/declare"], function(declare){ 
  var VanillaSoftServe = declare(null, { 
        constructor: function(){ 
          console.log("adding soft serve"); 
        } 
  }); 
  var OreoMixin = declare(null, { 
        constructor: function(){ 
          console.log("mixing in oreos"); 
        }, 
        kind: "plain"
  }); 
  var CookieDoughMixin = declare(null, { 
        constructor: function(){ 
          console.log("mixing in cookie dough"); 
        }, 
        chunkSize: "medium"
  }); 
  //继承VanillaSoftServe, OreoMixin, CookieDoughMixin三个类
  return declare([VanillaSoftServe, OreoMixin, CookieDoughMixin],{         
    constructor: function(){ console.log("A blizzard with " + this.kind + " oreos and " + this.chunkSize + "-sized chunks of cookie dough." 　　); 　　} }); 
});

通过“return declare([VanillaSoftServe, OreoMixin, CookieDoughMixin]......;”来返回我们所定义的类（widget），然后在其它的地方通过“require”或者“define”来指明变量引用该类（widget）。数组里面的对象“[VanillaSoftServe, OreoMixin, CookieDoughMixin]”是该自定义类的基类。需要强调一点，这里的declare省略了第一个变量：类的名称，即：“declare("pkg.MyClassName", [VanillaSoftServe, OreoMixin, CookieDoughMixin]......;”,如果设定这第一个变量，它会将这个字符串存储到该类的“declaredClass”变量中，同时会将"pkg.MyClassName"作为一个全局的变量用于今后方便构建该类的对象。

这段代码返回的信息为：

adding soft serve
mixing in oreos
mixing in cookie dough
A blizzard with plain oreos and medium-sized chunks of cookie dough.

以下是几种常用的写法：

1.声明一个类并将该类返回：

define(["dojo/_base/declare", "extension/bussiness/ModuleBussiness"]
, function (declare, ModuleBussiness) {
    var instance = declare(null, {
        //构造函数
        constructor: function (data) {
            this.data = data;
        },
        action: function () {
             ModuleBussiness.LayerToc();
        }
    });
    return instance;
});

设置该模块的名称为ModuleLayerTocCommand，则调用方式为：

require(['ModuleLayerTocCommand'], function (command) {
        var command = new command(params);
        command.action();
});

2.直接返回自定义类：调用方法同样是实例化后直接调用方法。

define(["dojo/_base/declare", "dojo/topic", "walk/bussiness/DrawToolBussiness", "com/events/EventManager"]
, function (declare, Topic, DrawToolBussiness, EventManager) {
    return declare(null, {
        //构造函数
        constructor: function (geoType, distance, redraw) {
            this.geoType = geoType;
            this.distance = distance;
            this.redraw = redraw;
        },
        action: function (callbackSuc) {
            EventManager.removeEvent();
            EventManager.deactivateMapTool();
            var params = {
                geoType: this.geoType,
                distance: this.distance,
                redraw: this.redraw
            };
            DrawToolBussiness.DrawBuffer(params, callbackSuc);
        }, 
        actionBuff: function (parm) {
            EventManager.removeEvent();
            EventManager.deactivateMapTool();
            DrawToolBussiness.DrawBuffer(parm.params, parm.callbackSuc);
        }
    });
});

3.使用单例模式：

define(['dojo/_base/declare', 'dojo/topic', 'dojo/dom-construct', 'dojo/dom-style', 'dojo/dom', 'dojo/on', 'dojo/domReady!'],
    function (declare, topic, DomConstruct, DomStyle, dom, on) {
        var instance = declare(null, {
            constructor: function (kwArgs) {
                if (instance.Instance) {
                    throw new Error('only one instance can be created');
                }
            },
            showProcess: function (container, title) {
                title = title || "正在加载...";
                var div = "<div id='ProcessBarDivCover' style='100%;height:100%;position:absolute;left:0px;top:0px;z-index:999991;background:#000;-ms-filter:alpha(opacity=15);filter:alpha(opacity=15); opacity:0.15;text-align:center;'></div>"
                var processBardiv = '<div id="ProcessBarDiv" style="background:url(themes/default/images/loading_background.png); 90px; height:85px; left:50%;top:50%;position:absolute;z-index:999992;margin:-43px 0 0 -45px">'
                    + '<img src="themes/default/images/loading.gif" alt="" style=" display:block; 40px; margin:12px auto 0 auto" />'
                    + '<div style=" color:#fff; font-size:12px; text-align:center;  margin-top:8px">' + title + '</div> '
                    + '</div>';
                //控制父级定位
                if (container) {
                    var position = DomStyle.get(container, "position");
                    if (position == undefined || position == "" || position == "static") {
                        DomStyle.set(container, "position", "relative");
                    }
                    DomConstruct.place(div, container, "last");
                    DomConstruct.place(processBardiv, container, "last");
                }
                else {
                    $(document.body).append(div);
                    $(document.body).append(processBardiv);
                }
                var $this = this;
                on(dom.byId("ProcessBarDivCover"), "dblclick", function () {
                    var tip = confirm("是否取消当前操作？");
                    if (tip) {
                        $this.closeProcess();
                        $this.Cancel();
                    }
                });
            },
            closeProcess: function () {
                DomConstruct.destroy("ProcessBarDiv");
                DomConstruct.destroy("ProcessBarDivCover");
            },
            Cancel: function () {///取消时候调用事件

            }
        });
        //单例
        if (instance.Instance == undefined || instance.Instance == null) {
            instance.Instance = new instance();
        }
        return instance;
    });