本文介绍了一种基于CocoaTouch框架的复杂JSON对象解析方法，利用递归和代理模式将JSON对象转换为JavaScript类实例，实现了类间的正确关联。
NOTE: 这里的JSON对象是指已经从JSON格式字符串转为JS对象的对象。所以，我这里要share的不是怎样把一个JSON格式的字符串转换为Javascript JSON对象，而是怎么样把JSON对象里的信息提取成一个一个的类实例。
这里还要提到的是我所采用的提取解析方式主要借鉴于Cocoa touch framwork. 在做iPhone开发之前，虽然对Delegate pattern也有所耳闻，但是并没有真正的大量的在工作中使用过。但是，做过iPhone开发的人应该都知道Cocoa touch framework里一个很重要的同时也是很便利的而且被大量使用的一种pattern就是Delegate, 它几乎无处不在。所以，基于在iPhone方面的开发经验以及自己对Delegate和NSXMLParser的理解，我决定也采用相同的方式对一个复杂JSON对象进行解析。
需求：把一个复杂JSON对象(只有数据没有function)按JSON对象内部表示的关系分解成一堆具有相同类关系的Javascript类实例。这个JSON对象是通过Jquery访问RESTful服务返回(服务器端返回的JSON字符串采用JSONLib生成)，所以RESTful服务返回的JSON格式字符串已经被JQuery转换为了JSON对象。简单说就是: 一个JSON大对象里每个子对象都用Javascript OO的类实例来表示, 同时这些实例之间的关联关系应该和大JSON对象里表示的一样。
NOTE: 大JSON对象里的属性名会多一个“@”符号以表示它是属性(这里的这种JSON格式在服)，如：
{
"person":[
{"@name":"handy", "@age":"18"},
{"@name":"wang", "@age":"20"}
]
}
如果是一个对象的key，那么就用普通字符串表示，如:"person".
下面贴被要被解析的JSON对象结构：
{
"screens": {"screen": [
{
"@id": "3",
"@name": "Light",
"@inverseScreenId": "64",
"background": {
"@fillScreen": "true",
"image": {"@src": "lightbackground1274950957643.png"}
},
"absolute": [
{
"@left": "43",
"@top": "108",
"@width": "86",
"@height": "52",
"button": {
"@id": "6",
"@name": "turn on",
"@hasControlCommand": "true"
}
},
{
"@left": "175",
"@top": "108",
"@width": "95",
"@height": "52",
"button": {
"@id": "8",
"@name": "turn off",
"@hasControlCommand": "true"
}
},
{
"@left": "127",
"@top": "174",
"@width": "185",
"@height": "54",
"label": {
"@id": "10",
"@fontSize": "14",
"@color": "#0000FF",
"@text": "light status",
"link": {
"@type": "sensor",
"@ref": "575",
"state": [
{
"@name": "off",
"@value": "light is off"
},
{
"@name": "on",
"@value": "light is on"
}
]
}
}
},
{
"@left": "195",
"@top": "240",
"@width": "50",
"@height": "50",
"switch": {
"@id": "12",
"link": {
"@type": "sensor",
"@ref": "575",
"state": [
{
"@name": "on",
"@value": "power.png"
},
{
"@name": "off",
"@value": "infrared.png"
}
]
}
}
},
{
"@left": "117",
"@top": "16",
"@width": "70",
"@height": "62",
"image": {
"@id": "14",
"@src": "OpenRemote.Logo.30x32.png",
"link": {
"@type": "sensor",
"@ref": "575",
"state": [
{
"@name": "off",
"@value": "lightbulboff1274938256022.png"
},
{
"@name": "on",
"@value": "lightbulb1274938250976.png"
}
]
},
"include": {
"@type": "label",
"@ref": "10"
}
}
},
{
"@left": "142",
"@top": "304",
"@width": "177",
"@height": "54",
"button": {
"@id": "29",
"@name": "To bedroom",
"navigate": {"@toGroup": "27"}
}
},
{
"@left": "142",
"@top": "361",
"@width": "176",
"@height": "52",
"button": {
"@id": "393",
"@name": "To background test",
"navigate": {
"@toGroup": "331",
"@toScreen": "332"
}
}
}
]
},
{
"@id": "64",
"@name": "Light",
"@landscape": "true",
"@inverseScreenId": "3",
"background": {
"@relative": "TOP",
"image": {"@src": "500X3001274943015264.png"}
},
"absolute": [
{
"@left": "184",
"@top": "112",
"@width": "84",
"@height": "82",
"image": {
"@id": "66",
"@src": "OpenRemote.Logo.30x32.png",
"link": {
"@type": "sensor",
"@ref": "575",
"state": [
{
"@name": "off",
"@value": "lightbulboff1274943081675.png"
},
{
"@name": "on",
"@value": "lightbulb1274943077035.png"
}
]
}
}
},
{
"@left": "126",
"@top": "22",
"@width": "212",
"@height": "52",
"label": {
"@id": "68",
"@fontSize": "14",
"@color": "#FF6600",
"@text": "light state",
"link": {
"@type": "sensor",
"@ref": "575",
"state": [
{
"@name": "off",
"@value": "OFF"
},
{
"@name": "on",
"@value": "ON"
}
]
}
}
},
{
"@left": "151",
"@top": "240",
"@width": "150",
"@height": "50",
"label": {
"@id": "322",
"@fontSize": "14",
"@color": "#FFFFFF",
"@text": "Test gesture"
}
}
],
"gesture": [
{
"@id": "105",
"@hasControlCommand": "true",
"@type": "swipe-bottom-to-top"
},
{
"@id": "102",
"@hasControlCommand": "true",
"@type": "swipe-top-to-bottom"
},
{
"@id": "127",
"@hasControlCommand": "true",
"@type": "swipe-left-to-right"
},
{
"@id": "132",
"@hasControlCommand": "true",
"@type": "swipe-right-to-left"
}
]
},
{
"@id": "15",
"@name": "Air_Condition",
"background": {
"@fillScreen": "true",
"image": {"@src": "air1274951021940.png"}
},
"absolute": [
{
"@left": "139",
"@top": "32",
"@width": "110",
"@height": "52",
"label": {
"@id": "18",
"@fontSize": "14",
"@color": "#3366FF",
"@text": "value",
"link": {
"@type": "sensor",
"@ref": "573"
}
}
},
{
"@left": "59",
"@top": "86",
"@width": "198",
"@height": "44",
"slider": {
"@id": "20",
"@vertical": "false",
"@passive": "false",
"link": {
"@type": "sensor",
"@ref": "573"
},
"min": {"@value": "0"},
"max": {"@value": "100"}
}
},
{
"@left": "267",
"@top": "178",
"@width": "44",
"@height": "198",
"slider": {
"@id": "24",
"@thumbImage": "vthumb1274939161708.png",
"@vertical": "true",
"@passive": "false",
"link": {
"@type": "sensor",
"@ref": "573"
},
"min": {
"@value": "0",
"@image": "vmin1274939127956.png",
"@trackImage": "vminTrack1274939151356.png"
},
"max": {
"@value": "100",
"@image": "vmax1274939183784.png",
"@trackImage": "vmaxTrack1274939173529.png"
}
}
},
{
"@left": "59",
"@top": "130",
"@width": "198",
"@height": "44",
"slider": {
"@id": "26",
"@thumbImage": "thumbImage1274939361119.png",
"@vertical": "false",
"@passive": "false",
"link": {
"@type": "sensor",
"@ref": "573"
},
"min": {
"@value": "0",
"@image": "low1274939314970.png",
"@trackImage": "red1274939338142.png"
},
"max": {
"@value": "100",
"@image": "high1274939397163.png",
"@trackImage": "green1274939382473.png"
}
}
},
{
"@left": "39",
"@top": "31",
"@width": "130",
"@height": "52",
"label": {
"@id": "63",
"@fontSize": "14",
"@color": "#FF6600",
"@text": "temperature:"
}
}
]
},
{
"@id": "71",
"@name": "TV",
"background": {
"@fillScreen": "true",
"image": {"@src": "tvbackground1274951037399.png"}
},
"absolute": [
{
"@left": "9",
"@top": "7",
"@width": "284",
"@height": "54",
"label": {
"@id": "98",
"@fontSize": "14",
"@color": "#000000",
"@text": "Test grid layout"
}
},
{
"@left": "14",
"@top": "272",
"@width": "248",
"@height": "52",
"label": {
"@id": "405",
"@fontSize": "14",
"@color": "#000000",
"@text": "Button 'Vol+' is repeatable"
}
}
],
"grid": {
"@left": "52",
"@top": "61",
"@width": "210",
"@height": "200",
"@rows": "4",
"@cols": "3",
"cell": [
{
"@x": "0",
"@y": "0",
"@rowspan": "1",
"@colspan": "1",
"button": {
"@id": "74",
"@name": "On",
"@hasControlCommand": "true"
}
},
{
"@x": "2",
"@y": "0",
"@rowspan": "1",
"@colspan": "1",
"button": {
"@id": "76",
"@name": "Off",
"@hasControlCommand": "true"
}
},
{
"@x": "1",
"@y": "0",
"@rowspan": "1",
"@colspan": "1",
"button": {
"@id": "78",
"@name": "Mute",
"@hasControlCommand": "true"
}
},
{
"@x": "0",
"@y": "2",
"@rowspan": "1",
"@colspan": "1",
"button": {
"@id": "80",
"@name": "Vol-",
"@hasControlCommand": "true"
}
},
{
"@x": "2",
"@y": "2",
"@rowspan": "1",
"@colspan": "1",
"button": {
"@id": "82",
"@name": "Vol+",
"@hasControlCommand": "true",
"@repeat": "true"
}
},
{
"@x": "1",
"@y": "1",
"@rowspan": "1",
"@colspan": "1",
"button": {
"@id": "84",
"@name": "Ch+",
"@hasControlCommand": "true"
}
},
{
"@x": "1",
"@y": "3",
"@rowspan": "1",
"@colspan": "1",
"button": {
"@id": "86",
"@name": "Ch-",
"@hasControlCommand": "true"
}
},
{
"@x": "1",
"@y": "2",
"@rowspan": "1",
"@colspan": "1",
"button": {
"@id": "88",
"@name": "Menu",
"@hasControlCommand": "true"
}
}
]
}
},
{
"@id": "30",
"@name": "Navigate_Buttons",
"background": {
"@fillScreen": "true",
"image": {"@src": "yesanpoh1274939752102.jpg"}
},
"absolute": [
{
"@left": "15",
"@top": "242",
"@width": "26",
"@height": "25",
"image": {
"@id": "33",
"@src": "turtle1274939826027.png"
}
},
{
"@left": "72",
"@top": "22",
"@width": "150",
"@height": "50",
"label": {
"@id": "415",
"@fontSize": "14",
"@color": "#000000",
"@text": "Test gesture"
}
},
{
"@left": "97",
"@top": "76",
"@width": "161",
"@height": "109",
"image": {
"@id": "421",
"@src": "lightbackground1275028518260.jpg"
}
}
],
"grid": {
"@left": "110",
"@top": "262",
"@width": "200",
"@height": "150",
"@rows": "3",
"@cols": "4",
"cell": [
{
"@x": "0",
"@y": "0",
"@rowspan": "1",
"@colspan": "2",
"button": {
"@id": "35",
"@name": "Login",
"navigate": {"@to": "login"}
}
},
{
"@x": "2",
"@y": "0",
"@rowspan": "1",
"@colspan": "2",
"button": {
"@id": "37",
"@name": "Logout",
"navigate": {"@to": "logout"}
}
},
{
"@x": "0",
"@y": "1",
"@rowspan": "1",
"@colspan": "2",
"button": {
"@id": "39",
"@name": "Setting",
"navigate": {"@to": "setting"}
}
},
{
"@x": "2",
"@y": "1",
"@rowspan": "1",
"@colspan": "2",
"button": {
"@id": "44",
"@name": "Back",
"navigate": {"@to": "back"}
}
},
{
"@x": "0",
"@y": "2",
"@rowspan": "1",
"@colspan": "4",
"button": {
"@id": "54",
"@name": "Next screen",
"navigate": {"@to": "nextScreen"}
}
}
]
},
"gesture": [
{
"@id": "416",
"@type": "swipe-bottom-to-top",
"navigate": {"@to": "logout"}
},
{
"@id": "417",
"@type": "swipe-top-to-bottom",
"navigate": {"@to": "login"}
},
{
"@id": "418",
"@type": "swipe-left-to-right",
"navigate": {"@to": "setting"}
}
]
},
{
"@id": "45",
"@name": "Button_Image",
"background": {
"@fillScreen": "true",
"image": {"@src": "whitebackground1274945911286.png"}
},
"absolute": [
{
"@left": "195",
"@top": "310",
"@width": "61",
"@height": "61",
"button": {
"@id": "48",
"@name": "Button",
"default": {"image": {"@src": "default1274940676120.png"}},
"pressed": {"image": {"@src": "pressed1274940704199.png"}}
}
},
{
"@left": "185",
"@top": "23",
"@width": "64",
"@height": "60",
"image": {
"@id": "50",
"@src": "bluerobot1274941389772.png"
}
},
{
"@left": "77",
"@top": "90",
"@width": "168",
"@height": "54",
"button": {
"@id": "52",
"@name": "Previous Screen",
"navigate": {"@to": "previousScreen"}
}
},
{
"@left": "76",
"@top": "163",
"@width": "179",
"@height": "56",
"button": {
"@id": "56",
"@name": "To livingroom",
"navigate": {"@toGroup": "2"}
}
},
{
"@left": "81",
"@top": "245",
"@width": "168",
"@height": "54",
"button": {
"@id": "58",
"@name": "Air condition",
"navigate": {
"@toGroup": "2",
"@toScreen": "15"
}
}
},
{
"@left": "31",
"@top": "314",
"@width": "150",
"@height": "50",
"label": {
"@id": "318",
"@fontSize": "14",
"@color": "#000000",
"@text": "Pressed button:"
}
},
{
"@left": "23",
"@top": "22",
"@width": "150",
"@height": "50",
"label": {
"@id": "320",
"@fontSize": "14",
"@color": "#000000",
"@text": "Image:"
}
}
]
},
{
"@id": "332",
"@name": "Absolute_10",
"background": {
"@absolute": "10,10",
"image": {"@src": "yesanpo1275017627763.jpg"}
},
"absolute": [
{
"@left": "127",
"@top": "92",
"@width": "161",
"@height": "52",
"label": {
"@id": "371",
"@fontSize": "14",
"@color": "#FF6600",
"@text": "Absolut (10,10)"
}
},
{
"@left": "93",
"@top": "350",
"@width": "150",
"@height": "52",
"button": {
"@id": "391",
"@name": "To livingroom",
"navigate": {
"@toGroup": "2",
"@toScreen": "3"
}
}
}
]
},
{
"@id": "335",
"@name": "Left",
"background": {
"@relative": "LEFT",
"image": {"@src": "yesanpo1275017627763.jpg"}
},
"absolute": {
"@left": "128",
"@top": "73",
"@width": "150",
"@height": "50",
"label": {
"@id": "373",
"@fontSize": "14",
"@color": "#FF6600",
"@text": "Left"
}
}
},
{
"@id": "339",
"@name": "Top",
"background": {
"@relative": "TOP",
"image": {"@src": "yesanpo1275017627763.jpg"}
},
"absolute": {
"@left": "84",
"@top": "82",
"@width": "150",
"@height": "50",
"label": {
"@id": "375",
"@fontSize": "14",
"@color": "#FF6600",
"@text": "Top"
}
}
},
{
"@id": "343",
"@name": "Right",
"background": {
"@relative": "RIGHT",
"image": {"@src": "yesanpo1275017627763.jpg"}
},
"absolute": {
"@left": "46",
"@top": "73",
"@width": "150",
"@height": "50",
"label": {
"@id": "377",
"@fontSize": "14",
"@color": "#FF6600",
"@text": "Right"
}
}
},
{
"@id": "347",
"@name": "Bottom",
"background": {
"@relative": "BOTTOM",
"image": {"@src": "yesanpo1275017627763.jpg"}
},
"absolute": {
"@left": "83",
"@top": "63",
"@width": "150",
"@height": "50",
"label": {
"@id": "379",
"@fontSize": "14",
"@color": "#FF6600",
"@text": "Bottom"
}
}
},
{
"@id": "351",
"@name": "Top_Left",
"background": {
"@relative": "TOP_LEFT",
"image": {"@src": "yesanpo1275017627763.jpg"}
},
"absolute": {
"@left": "122",
"@top": "80",
"@width": "150",
"@height": "50",
"label": {
"@id": "381",
"@fontSize": "14",
"@color": "#FF6600",
"@text": "Top_Left"
}
}
},
{
"@id": "355",
"@name": "Top_Right",
"background": {
"@relative": "TOP_RIGHT",
"image": {"@src": "yesanpo1275017627763.jpg"}
},
"absolute": {
"@left": "45",
"@top": "83",
"@width": "150",
"@height": "50",
"label": {
"@id": "383",
"@fontSize": "14",
"@color": "#FF6600",
"@text": "Top_Right"
}
}
},
{
"@id": "359",
"@name": "Center",
"background": {
"@relative": "CENTER",
"image": {"@src": "yesanpo1275017627763.jpg"}
},
"absolute": {
"@left": "78",
"@top": "72",
"@width": "150",
"@height": "50",
"label": {
"@id": "385",
"@fontSize": "14",
"@color": "#FF6600",
"@text": "Center"
}
}
},
{
"@id": "363",
"@name": "Bottom_Left",
"background": {
"@relative": "BOTTOM_LEFT",
"image": {"@src": "yesanpo1275017627763.jpg"}
},
"absolute": {
"@left": "128",
"@top": "65",
"@width": "150",
"@height": "50",
"label": {
"@id": "387",
"@fontSize": "14",
"@color": "#FF6600",
"@text": "Bottom_Left"
}
}
},
{
"@id": "367",
"@name": "Bottom_Right",
"background": {
"@relative": "BOTTOM_RIGHT",
"image": {"@src": "yesanpo1275017627763.jpg"}
},
"absolute": {
"@left": "41",
"@top": "64",
"@width": "150",
"@height": "50",
"label": {
"@id": "389",
"@fontSize": "14",
"@color": "#FF6600",
"@text": "Bottom_Right"
}
}
}
]},
"groups": {"group": [
{
"@id": "2",
"@name": "Livingroom",
"include": [
{
"@type": "screen",
"@ref": "3"
},
{
"@type": "screen",
"@ref": "64"
},
{
"@type": "screen",
"@ref": "15"
},
{
"@type": "screen",
"@ref": "71"
}
]
},
{
"@id": "27",
"@name": "Bedroom",
"include": [
{
"@type": "screen",
"@ref": "30"
},
{
"@type": "screen",
"@ref": "45"
}
]
},
{
"@id": "331",
"@name": "BackgroundTest",
"include": [
{
"@type": "screen",
"@ref": "332"
},
{
"@type": "screen",
"@ref": "335"
},
{
"@type": "screen",
"@ref": "339"
},
{
"@type": "screen",
"@ref": "343"
},
{
"@type": "screen",
"@ref": "347"
},
{
"@type": "screen",
"@ref": "351"
},
{
"@type": "screen",
"@ref": "355"
},
{
"@type": "screen",
"@ref": "359"
},
{
"@type": "screen",
"@ref": "363"
},
{
"@type": "screen",
"@ref": "367"
}
]
}
]}
}
哈哈哈哈。是不是看着都很烦呀。没事，慢慢一步一步的来。
下面贴解析上面JSON对象的代码:
JSONParser.js
JSONParser = (function() {
return function(jsonDataParam, delegateParam) {
var self = this;
var jsonData = jsonDataParam;
var delegate = delegateParam;
this.startParse = function() {
recursiveParse(null, jsonData);
};
this.setDelegate = function(delegateParam) {
delegate = delegateParam;
};
function recursiveParse(nodeName, jsonData) {
var properties = {};
var isLeaf = true;
for (var key in jsonData) {
var value = jsonData[key];
if (key.toString().indexOf("@") === 0) {
properties[key] = value;
} else {
isLeaf = false;
}
}
if (nodeName != null) {
delegate.didParse(self, nodeName, properties);
}
if (isLeaf) {
return;
}
for (var key in jsonData) {
var value = jsonData[key];
if (key.toString().indexOf("@") === 0) {
continue;
}else if (Object.prototype.toString.apply(value) === "[object Array]") {
for(var index in value) {
var oldDelegate = delegate;
recursiveParse(key, value[index]);
self.setDelegate(oldDelegate);
}
} else {
var oldDelegate = delegate;
recursiveParse(key, value);
self.setDelegate(oldDelegate);
}
}
}
};
})();
Worker.js
Worker = (function() {
return function() {
this.parseJSONData(jsonData) {
var jsonParser = new JSONParser(jsonData, self);
jsonParser.startParse();
}
// Delegate methods of JSONParser
this.didParse = function(jsonParser, nodeName, properties) {
if (nodeName == "screen") {
RenderDataDB.getInstance().addScreen(new Screen(jsonParser, properties));
} else if (nodeName == "group") {
RenderDataDB.getInstance().addGroup(new Group(jsonParser, properties));
}
};
}
})();
Screen.js
Screen = (function() {
return function(jsonParser, properties) {
// For extend
Screen.superClass.constructor.call(this, jsonParser, properties);
var self = this;
this.background = null;
// Delegate method of JSONParser.
this.didParse = function(jsonParser, nodeName, properties) {
if (nodeName == "background") {
this.background = new Background(jsonParser, properties);
} else if (nodeName == "absolute") {
// TODO
}
};
// Private methods
function init(jsonParser, properties) {
jsonParser.setDelegate(self);
self.className = "Screen";
}
// Init jobs
init(jsonParser, properties);
}
})();
ClassUtils.extend(Screen, BaseModel);
代码贴了(一些不重要的没有贴，不会影响整个解析机制)，下面还是解释一下吧。
上面JS代码的入口是Workker.js的parserData方法, 形参jsonData就是刚才说的那个大JSON对象(形如: {....} )。
主要是解释JSONParser.js 的recursiveParse方法：
在recursiveParse方法里的最外层有两个循环，而且这两个循环都是对同一个数据jsonData, 可能你会问为什么呢？如果，我不写这篇blog的话，再过个一年半年的，我只能对你说:"God knows!". 开玩笑的。可能再过一段时间来看代码的话，我还得从头捋，想想都可怕。这就是为什么我要写下这一篇blog.第一个循环是把节点的所以属性存起来，等循环结束后，通过delegate实例把nodeName和它的属性传给delegate实例，然后第二个循环再去遍历节点的子节点(递归方式)。这样做的好处是：在第一个循环结束后，调用了delegate的didParse方法(jsonParser把自己的实例也传过去了)，这样在Delegate实例那边就可以有机会改变jsonParser实例的delegate(可把delegate引用修改为下一次要接收nodeName, properties的实例， Screen类就是这样做的), 等recursiveParse方法解析子节点时候，jsonParser的delegate就是修改后的实例。从而那个实例就可以接收nodeName和properties了。但是请注意在recursiveParse方法里还有这样一个代码片断：
else if (Object.prototype.toString.apply(value) === "[object Array]") {
for(var index in value) {
var oldDelegate = delegate;
recursiveParse(key, value[index]);
self.setDelegate(oldDelegate);
}
} else {
var oldDelegate = delegate;
recursiveParse(key, value);
self.setDelegate(oldDelegate);
}
这个代码片断里有两处先
var oldDelegate = delegate;
再
self.setDelegate(oldDelegate);
那么这样做的目的是什么呢？目的就是当子结点解析完后了，要把原来的delegate恢复, 不然当与父节点同级的节点有多个时，把当前父结点以及以下的结点都解析完后，对下一个与父结点同点的节点解析时，调用
delegate.didParse(self, nodeName, properties);
时，这里的delegate是解析上一个同级节点时，
delegate.didParse(self, nodeName, properties);
方法里面修改后的delegate实例。所以当解析下一个父结点并再次调用
delegate.didParse(self, nodeName, properties);
时，真正期望的delegte实例却接收不到nodeName和properties。
说到这里，肯定有人会问，为什么不把两个循环合成一个来做呢，这样效率还高一些。不错，那样效率是高，其实之前我就是那样去做的，但是那样没有实现功能。因为
delegate.didParse(self, nodeName, properties);
在最后即在循环外面，大家知道递归的特点就是至底向上，那么不合成一个循环的原因也就有了。因为到递归调用到最底一层时，那时的delegateg还是JSONParser实例化的时候的那个delegte, 所以这样没法把nodeName和properties通过这个delegate实例传给最底一层节点对应的自定义的Javascript类实例。
下面的事就是去慢慢理解了。最重要的事看有没有BUG!!!
扫一扫
77
被折叠的 条评论
为什么被折叠?
到【灌水乐园】发言
