JSON基础知识总结_H5之家 - 中国HTML5教程资源分享第一站

一、总结

JSON对象是一个无序的"名称/值"对的集合
它开始于“{”，结束于“}”。每一个属性名和值间用“:”提示，属性间用“,”分隔。一个数组开始于"["，结束于"]"，值之间用","分隔。

数组和List转换为JSON用JSONArray.fromObject
Map、bean、beans(保存在一个List中转换)转换为JSON用 JSONObject.fromObject

JSONObject.toBean(JSONObject类型,Class类型) // 转换为对象(如自定义类对象，Map对象等)

JSON （JavaScript Object Notation）是一种轻量级的数据交换格式，非常适合于服务器与 JavaScript 的交互.
JSON 是 JavaScript 原生格式，这意味着在 JavaScript 中处理 JSON 数据不需要任何特殊的 API 或工具包。

Json必需的包（重新导入包后需重启下，因为这个问题浪费了我好长时间，需注意）
commons-beanutils.jar
commons-lang-2.4.jar
commons-logging-1.1.1.jar
json-lib-2.2.3-jdk13.jar
ezmorph-1.0.6.jar
commons-collections-3.2.1.jar

<script language="javascript">

 function showJSON() {   
     var user =    
     {    
         "username":"andy",   
         "age":20,   
         "info": { "tel": "123456", "cellphone": "98765"},   
         "address":   
             [   
                 {"city":"beijing","postcode":"222333"},   
                 {"city":"newyork","postcode":"555666"}   
             ]   
     }           
     alert(user.username);   
     alert(user.age);   
     alert(user.info.cellphone); 
//或       user.info["cellphone"]  
     alert(user.address[0].city);   
     alert(user.address[0].postcode);   
 } 
</script>

这表示一个user对象，拥有username, age, info, address 等属性。
同样也可以用JSON来简单的修改数据，修改上面的例子
js 代码

 function showJSON() {   
     var user =    
     {    
         "username":"andy",   
         "age":20,   
         "info": { "tel": "123456", "cellphone": "98765"},   
         "address":   
             [   
                 {"city":"beijing","postcode":"222333"},   
                 {"city":"newyork","postcode":"555666"}   
             ]   
     }           
     user.username = "Tom";   
     alert(user.username);   
 }

易错地方 (注意有无外引号)：

    function testJson(){
    	 
    	 var str = { "name": "Violet", "password": "character" };   //JSON类型对象
//无引号，是JSON对象
    	 alert(typeof(str));  //JSON类型
         alert(str.password); 

         //alert(obj.toJSONString());  
         
          var a=50,b="xxx";
          var arr="{id:"+a+",name:'"+b+"'}"; //string类型
              //字符串拼接为可转换为JSON的String 
  
          var str2 = '{ "name": "Violet", "password": "character" }';     
//有引号，是String类型对象        
          alert(typeof(str2)); //string类型
          var obj = eval('(' + str2 + ')');  //转换为JSON类型
          alert(typeof(obj)); //JSON类型
          alert(obj.name);  //Violet
    }
    </script>

		   JSONObject resultJSON = new JSONObject(); 
		   resultJSON.put("param1", 1);
		   resultJSON.put("param2", 2);
		   resultJSON.put("param3", 3);
		   System.out.println(resultJSON);  
		   //{"param1":1,"param2":2,"param3":3}

二、Java代码转换成json代码

1.List集合转换成json代码+
List list = new ArrayList();
list.add( "first" );
list.add( "second" );
JSONArray jsonArray2 = JSONArray.fromObject( list );

2.Map集合转换成json代码
Map map = new HashMap();
map.put("name", "json");
map.put("bool", Boolean.TRUE);
map.put("int", new Integer(1));
map.put("arr", new String[] { "a", "b" });
map.put("func", "function(i){ return this.arr[i]; }");
JSONObject json = JSONObject.fromObject(map);
//{"func":function(i){ return this.arr[i]; },"arr":["a","b"],"int":1,"name":"json","bool":true}

3.Bean转换成json代码
JSONObject jsonObject = JSONObject.fromObject(new JsonBean());

//当是对象的时候
Student student = new Student();
student.setAge(18);
student.setName("zhangsan");
student.setSex("male");
JSONObject jsonObject = JSONObject.fromObject(student);
System.out.println(jsonObject);//输出{"age":18,"name":"zhangsan","sex":"male"}

4.数组转换成json代码
boolean[] boolArray = new boolean[] { true, false, true };
JSONArray jsonArray1 = JSONArray.fromObject(boolArray);

5.beans转换成json代码
List userInfosList = new ArrayList<UserInfo>();
   UserInfo u1 = new UserInfo();
   u1.setUserId(10000);
   u1.setUserName("qqqqq");
   u1.setPassword("111111");
   UserInfo u2 = new UserInfo();
   u2.setUserId(10001);
   u2.setUserName("wwwww");
   u2.setPassword("222222");
   userInfosList.add(u1);
   userInfosList.add(u2);
   JSONArray json2=JSONArray.fromObject(userInfosList);

     Iterator it=json2.listIterator();
        while(it.hasNext())
        {

            JSONObject obj=(JSONObject)it.next();
            UserInfo u=(UserInfo)JSONObject.toBean(obj,UserInfo.class);
            System.out.println(u.getPassword());
        }

6、String转JSON

String listStr = "['apple','orange']";		
		//JSONArray json = JSONArray.fromObject(listStr);
				//结果：["apple","orange"]
		//必须用JSONArray来转，用JSONObject会出现以下错误信息：
			// A JSONObject text must begin with '{' at character 1 of ['apple','orange']
		
		String mapStr2 = "{'apple','orange'}";
		JSONObject json = JSONObject.fromObject(mapStr2);
		//用JSONObject必须是键值对，上面会出现以下错误：
			//Expected a ':' after a key at character 9 of {'apple','orange'}		
		
		String mapStr1 = "{'age':30,'name':'Michael','baby':['Lucy','Lily']}";		
		JSONObject json2 = JSONObject.fromObject(mapStr1);
				//{"age":30,"name":"Michael","baby":["Lucy","Lily"]}		
		
		System.out.println(json);

三、JSON转List、Map

转List： JSONArray.toCollection(json)

//JSON转List
		String str = "['apple','orange']";
		JSONArray json = JSONArray.fromObject(str);
		Collection<String> list = JSONArray.toCollection(json);
		for (String s : list) {
			   System.out.println(s);
		}

转Map：JSONObject.toBean(json , Map.class)

//JOSN转Map
		String mapStr = "{'age':30,'name':'Michael','baby':['Lucy','Lily']}";
		JSONObject json3 = JSONObject.fromObject(mapStr);
		Map<String, Object> map = (Map) JSONObject.toBean(json3, Map.class);
		for (Map.Entry<String, Object> entry : map.entrySet()) {
		    System.out.println(entry.getKey() + " " + entry.getValue());
		}
		//name Michael
		//age 30
		//baby [Lucy, Lily]

注意其Str转JSON问题！

四、遍历JSON数据的两种常用方式

 var json={"status":1,"info":"u83b7u53d6u6210u529f","data":[{"id":"4","name":"u77f3u5bb6u5e84","information":"u5e02","Region_id":"3","type":"1"}]}
 var data=json.data;
 for(i=0;i<data.length;i++)
 {
     document.write("Name:"+data[i].name+",Info:"+data[i].information+"");
 }

var json=[{"kl_id":"2","kl_title":"Test date1","kl_content":"Test date2","kl_type":"3","id":"6"},{"kl_id":"2","kl_title":"Test1","kl_content":"Test2","kl_type":"1","id":"9"}]
    var str = "";
    for (var one in json)
     {
        for(var key in json[one])
         {
             str += json[one][key] + ",";
         }
     }
     document.write(str);

List list = query.list();
List<String> excList = new ArrayList<String>();
		if(list!=null && list.size()>0){
			for (int i = 0; i < list.size(); i++) {
				Object[] obj = (Object[]) list.get(i);
				EipAnalysisServiceExc excR=new EipAnalysisServiceExc();
				excR.setId(Long.parseLong(obj[0].toString()));
				excR.setServiceName(obj[1]!=null?obj[1].toString():null);
				
				excList.add(JSONObject.fromObject(excR).toString());
			}
		}


for (int i = 0; i < excList.size(); i++) {
	JSONObject jSONObject = JSONObject.fromObject(excList.get(i));
	EipAnalysisServiceExc exc = JSONObject.toBean(jSONObject, EipAnalysisServiceExc.class);
		}


/*由JSONObject.fromObject(excR)得到JSONObject对象，然后toString传输，再JSONObject.fromObject解析为JSONObject对象
使用JSONObject.toBean(JSONObject类型,Class类型)  // 转换为对象(如自定义类对象，Map对象等) 转换为类类型
*/