json对象格式化字符串输出

转自：http://www.cnitblog.com/seeyeah/archive/2009/09/29/61618.html

函数的主要功能是：传入一个Json对象（为了节省空间，一般请求返回的Json都是没有格式化的，可读性不好），可以输出格式化字符串，提高Json可读性。
虽然很多IDE或工具已经实现，但有时做简单测试时，格式化还是需要的。

假设，JS调用（假设界面有一个id为result的textarea）

var json = {
    Id: 1,
    Name: "Test",
    Date: new Date(),
    Subjects:
    [
        {
            Name: "语文"
        },
        {
            Name: "数学"
        },
        {
            Name: "英语",
            Marks: [90, 100, 83, { Test: "aaa"}]
        }
    ],
    Company:
    {
        Name: "Microsoft",
        Location: "USA"
    },
    Test: null
};
//-------------测试
//格式化Json字符串
document.getElementById("result").value = JsonUti.convertToString(json);

界面输出


实现代码如下:

        var JsonUti = {
            //定义换行符
            n: "\n",
            //定义制表符
            t: "\t",
            //转换String
            convertToString: function(obj) {
                return JsonUti.__writeObj(obj, 1);
            },
            //写对象
            __writeObj: function(obj    //对象
                    , level             //层次（基数为1）
                    , isInArray) {       //此对象是否在一个集合内
                //如果为空，直接输出null
                if (obj == null) {
                    return "null";
                }
                //为普通类型，直接输出值
                if (obj.constructor == Number || obj.constructor == Date || obj.constructor == String || obj.constructor == Boolean) {
                    var v = obj.toString();
                    var tab = isInArray ? JsonUti.__repeatStr(JsonUti.t, level - 1) : "";
                    if (obj.constructor == String || obj.constructor == Date) {
                        //时间格式化只是单纯输出字符串，而不是Date对象
                        return tab + ("\"" + v + "\"");
                    }
                    else if (obj.constructor == Boolean) {
                        return tab + v.toLowerCase();
                    }
                    else {
                        return tab + (v);
                    }
                }
 
                //写Json对象，缓存字符串
                var currentObjStrings = [];
                //遍历属性
                for (var name in obj) {
                    var temp = [];
                    //格式化Tab
                    var paddingTab = JsonUti.__repeatStr(JsonUti.t, level);
                    temp.push(paddingTab);
                    //写出属性名
                    temp.push(name + " : ");
 
                    var val = obj[name];
                    if (val == null) {
                        temp.push("null");
                    }
                    else {
                        var c = val.constructor;
 
                        if (c == Array) { //如果为集合，循环内部对象
                            temp.push(JsonUti.n + paddingTab + "[" + JsonUti.n);
                            var levelUp = level + 2;    //层级+2
 
                            var tempArrValue = [];      //集合元素相关字符串缓存片段
                            for (var i = 0; i < val.length; i++) {
                                //递归写对象                         
                                tempArrValue.push(JsonUti.__writeObj(val[i], levelUp, true));
                            }
 
                            temp.push(tempArrValue.join("," + JsonUti.n));
                            temp.push(JsonUti.n + paddingTab + "]");
                        }
                        else if (c == Function) {
                            temp.push("[Function]");
                        }
                        else {
                            //递归写对象
                            temp.push(JsonUti.__writeObj(val, level + 1));
                        }
                    }
                    //加入当前对象“属性”字符串
                    currentObjStrings.push(temp.join(""));
                }
                return (level > 1 && !isInArray ? JsonUti.n : "")                       //如果Json对象是内部，就要换行格式化
                    + JsonUti.__repeatStr(JsonUti.t, level - 1) + "{" + JsonUti.n     //加层次Tab格式化
                    + currentObjStrings.join("," + JsonUti.n)                       //串联所有属性值
                    + JsonUti.n + JsonUti.__repeatStr(JsonUti.t, level - 1) + "}";   //封闭对象
            },
            __isArray: function(obj) {
                if (obj) {
                    return obj.constructor == Array;
                }
                return false;
            },
            __repeatStr: function(str, times) {
                var newStr = [];
                if (times > 0) {
                    for (var i = 0; i < times; i++) {
                        newStr.push(str);
                    }
                }
                return newStr.join("");
            }
        };
 

实例下载：JsonToString.rar