https://staticcn.ihuaben.com/localdb/localdb.js

1/*
2	 * Copyright 2010 Nicholas C. Zakas. All rights reserved.
3	 * BSD Licensed.
4	 * modified by wushufeng 2014-07-01
5	 */
6	$.XDStorage = function(origin, path){
7	    this.origin = origin;
8	    this.path = path;
9	    this._iframe = null;
10	    this._iframeReady = false;
11	    this._queue = [];
12	    this._requests = {};
13	    this._id = 0;
14	}
15	
16	$.XDStorage.prototype = {
17	
18		op:{
19			WRITE: 'W',
20			READ: 'R',
21			DEL: 'D',
22			CLEAR: 'X'
23		},
24	    //restore constructor
25	    constructor: $.XDStorage,
26	
27	    //public interface methods
28	
29	    init: function(){
30	
31	        var that = this;
32	
33	        if (!this._iframe){
34	            if (window.postMessage && window.JSON && window.localStorage){
35	                this._iframe = document.createElement("iframe");
36	                this._iframe.style.cssText = "position:absolute;width:1px;height:1px;left:-9999px;";
37	                document.body.appendChild(this._iframe);
38	
39	                if (window.addEventListener){
40	                    this._iframe.addEventListener("load", function(){ that._iframeLoaded(); }, false);
41	                    window.addEventListener("message", function(event){ that._handleMessage(event); }, false);
42	                } else if (this._iframe.attachEvent){
43	                    this._iframe.attachEvent("onload", function(){ that._iframeLoaded(); }, false);
44	                    window.attachEvent("onmessage", function(event){ that._handleMessage(event); });
45	                }
46	            } else {
47	                throw new Error("Unsupported browser.");
48	            }
49	        }
50	
51	        this._iframe.src = this.origin + this.path;
52	
53	    },
54
55	    getValue: function(key, callback){
56	        this._toSend({
57                key: key
58            },callback);
59	    },
60	
61	    setValue: function(key,value,callback){
62
63	        this._toSend({
64                key: key,
65    			op:  this.op.WRITE,
66    			value: value
67            },callback);	
68	    },
69	    delValue: function(key,callback){
70	        this._toSend({
71                key: key,
72    			op: this.op.DEL
73            },callback);	
74	    },
75	    clearValue: function(callback){
76	        this._toSend({
77    			op: this.op.CLEAR
78            },callback);	
79	    },
80	    //private methods
81	    
82	    _toSend: function(params,callback){
83	    	var data = {
84	                request: {
85	                    key: params.key,
86	                    id: ++this._id,
87	                    op: params.op,
88	                    value: params.value
89	                },
90	                callback: callback
91            };
92	    	if (this._iframeReady){
93	            this._sendRequest(data);
94	        } else {
95	            this._queue.push(data);
96	        }   
97	
98	        if (!this._iframe){
99	            this.init();
100	        }	
101	    },
102	
103	    _sendRequest: function(data){
104	        this._requests[data.request.id] = data;
105	        this._iframe.contentWindow.postMessage(JSON.stringify(data.request), this.origin);
106	    },
107	
108	    _iframeLoaded: function(){
109	        this._iframeReady = true;
110	
111	        if (this._queue.length){
112	            for (var i=0, len=this._queue.length; i < len; i++){
113	                this._sendRequest(this._queue[i]);
114	            }
115	            this._queue = [];
116	        }
117	    },
118	
119	    _handleMessage: function(event){
120	        if (event.origin == this.origin){
121	            var data = JSON.parse(event.data);
122	            if(this._requests[data.id]&&this._requests[data.id].callback)
123					this._requests[data.id].callback(data.value);
124	            delete this._requests[data.id];
125	        }
126	    }
127	
128	};
129