Android json数据解析

前言

喜欢在前言里讲一下自己的现状，或许能有共鸣的同学，更多的是留给自己一个纪念，几个月或者几年再回来看的时候还是会很有感慨。今天说说语言，json这种数据格式之前我做服务器端的时候天天接触，天真的以为json的世界里只有php的json_encode和json_decode，今天当我做客户端的时候，竟然将近一个多小时才搞定json的解析。这里我不是抨击php好坏，只是想说多学点东西，看看你不熟悉的领域，方能开阔自己的视野，方能知道天外有天，方能知道当初你看不上的工作其实你也不一定能很好的完成，扯多了，回来讲解json 

什么是json

json（Javascript Object Natation）是一种轻量级的数据交换格式，相比xml这种数据交换格式来说，json相对解析更加简单一些，因此客户端和服务器的数据交换格式往往通过json进行交换 
json一共有两种数据结构，一种是以（key/value）对形式存在的无序的jsonObject对象，一个对象以“{”（左花括号）开始，“}”（右花括号）结束。每个“名称”后跟一个“:”（冒号）; “名称/值”对之间使用“,”（逗号） 


例如：{”name“:"zhengyi.wzy"}，这就是一个最简单的json对象，对于这种数据格式，key值必须是String，而value则可以是String，Number，Object，Array等数据类型 


另一种数据格式就是有序的value的集合，这种形式被称为是jsonArray，数组是值（value）的有序集合。一个数组以”[“（左中括号）开始，”]“（右中括号）结束。值之间使用”,“（逗号）分隔 
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解析json字符串

解析json字符串的步骤一般如下所示： 
（1） 创建JSONObject： 

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1 2	// Create a JSONObject JSONObject jsonObject = new JSONObject(result);

（2） 获取JSONArray，遍历JSONArray数组 

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// To get a specific JSONArray JSONArray jsonArray = jsonObject.getJSONArray("contacts");   // To get items from the array for (int i = 0; i < jsonArray.length(); i ++) {     // TODO：Traverse the jsonarray }

（3） 获取JSONObject 

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// Create a JSONObject JSONObject jsonObject = new JSONObject(result);   // To get a specific JSONArray JSONArray jsonArray = jsonObject.getJSONArray("contacts");   // To get items from the array for (int i = 0; i < jsonArray.length(); i++) {     // To get a specific JSONObject     JSONObject oneObject = jsonArray.getJSONObject(i); }

（4）获取特定字符串 

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// Create a JSONObject JSONObject jsonObject = new JSONObject(result);   // To get a specific JSONArray JSONArray jsonArray = jsonObject.getJSONArray("contacts");   // To get items from the array for (int i = 0; i < jsonArray.length(); i++) {     // To get a specific JSONObject     JSONObject oneObject = jsonArray.getJSONObject(i);       // To get a specific string     String id = oneObject.getString("id");     String name = oneObject.getString("name");       Log.e("wzy", "id is:" + id + ", name is " + name); }

解析结果： 

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03-05 10:26:08.690: E/wzy(26401): id is:c200, name is Ravi Tamada 03-05 10:26:08.690: E/wzy(26401): id is:c201, name is Johnny Depp 03-05 10:26:08.690: E/wzy(26401): id is:c202, name is Leonardo Dicaprio 03-05 10:26:08.690: E/wzy(26401): id is:c203, name is John Wayne 03-05 10:26:08.691: E/wzy(26401): id is:c204, name is Angelina Jolie 03-05 10:26:08.691: E/wzy(26401): id is:c205, name is Dido 03-05 10:26:08.691: E/wzy(26401): id is:c206, name is Adele 03-05 10:26:08.692: E/wzy(26401): id is:c207, name is Hugh Jackman 03-05 10:26:08.693: E/wzy(26401): id is:c208, name is Will Smith 03-05 10:26:08.693: E/wzy(26401): id is:c209, name is Clint Eastwood 03-05 10:26:08.694: E/wzy(26401): id is:c2010, name is Barack Obama 03-05 10:26:08.694: E/wzy(26401): id is:c2011, name is Kate Winslet 03-05 10:26:08.695: E/wzy(26401): id is:c2012, name is Eminem