xml和json格式文件简单对比

定义：

XML 指可扩展标记语言（eXtensible Markup Language）。被设计用来传输和存储数据

XPath 是一门在 XML文档中查找信息的语言。XPath可用来在 XML 文档中对元素和属性进行遍历。
它是 W3C XSLT 标准的主要元素，并且 XQuery 和 XPointer 都构建于 XPath 表达之上。

所以，对 XPath 的理解是很多高级 XML 应用的基础。

JSON: JavaScript Object Notation(JavaScript 对象表示法)，是存储和交换文本信息的语法，类似 XML；JSON 比 XML 更小、更快，更易解析
JSON 独立于语言：JSON 使用 Javascript语法来描述数据对象，但是 JSON 仍然独立于语言和平台。JSON 解析器和 JSON 库支持许多不同的编程语言。目前非常多的动态（PHP，JSP，.NET）编程语言都支持JSON

xpath跟jsonpath区别

XPath	JSONPath	Description
/	$	the root object/element
.	@	the current object/element
/	. or []	child operator
..	n/a	parent operator
//	..	recursive descent. JSONPath borrows this syntax from E4X.
*	*	wildcard. All objects/elements regardless their names.
@	n/a	attribute access. JSON structures don't have attributes.
[]	[]	subscript operator. XPath uses it to iterate over element collections and for predicates. In Javascript and JSON it is the native array operator.
|	[,]	Union operator in XPath results in a combination of node sets. JSONPath allows alternate names or array indices as a set.
n/a	[start:end:step]	array slice operator borrowed from ES4.
[]	?()	applies a filter (script) expression.
n/a	()	script expression, using the underlying script engine.
()	n/a	grouping in Xpath

举例：

json示例

{ "store": {
    "book": [ 
      { "category": "reference",
        "author": "Nigel Rees",
        "title": "Sayings of the Century",
        "price": 8.95
      },
      { "category": "fiction",
        "author": "Evelyn Waugh",
        "title": "Sword of Honour",
        "price": 12.99
      },
      { "category": "fiction",
        "author": "Herman Melville",
        "title": "Moby Dick",
        "isbn": "0-553-21311-3",
        "price": 8.99
      },
      { "category": "fiction",
        "author": "J. R. R. Tolkien",
        "title": "The Lord of the Rings",
        "isbn": "0-395-19395-8",
        "price": 22.99
      }
    ],
    "bicycle": {
      "color": "red",
      "price": 19.95
    }
  }
}

XPath	JSONPath	Result
/store/book/author	$.store.book[*].author	the authors of all books in the store
//author	$..author	all authors
/store/*	$.store.*	all things in store, which are some books and a red bicycle.
/store//price	$.store..price	the price of everything in the store.
//book[3]	$..book[2]	the third book
//book[last()]	$..book[(@.length-1)] $..book[-1:]	the last book in order.
//book[position()<3]	$..book[0,1] $..book[:2]	the first two books
//book[isbn]	$..book[?(@.isbn)]	filter all books with isbn number
//book[price<10]	$..book[?(@.price<10)]	filter all books cheapier than 10
//*	$..*	all Elements in XML document. All members of JSON structure.

参考：http://goessner.net/articles/JsonPath/