JSONArray和JSONObject的簡單使用

一、爲什麼要使用JSONArray和JSONObject

1、後臺 --》前臺 可以把java對象和集合轉化成json字符串格式，這樣在前臺的ajax方法中可以直接轉化成json對象使用 ，從後臺向前臺傳值

2、前臺 --》使用JSON.stringify(mdses)方法把js對象，數組，轉化成json字符串 ，後臺使用JSONArray或JSONObject 轉化成 java對象或集合 

     有助於前端參數傳遞到後端，和後端取值y

3、json現在以成爲大多數據傳輸的載體 

二、後臺解析前臺ajax提交數據,使用較少一般都把list 或map轉化爲json形式的字符串傳值到前臺的ajax中：

	//根據接收的json字符串來解析字符串中所包含的數據和數據對象
	@Test
	public void parsJsonFromFront(){
		//接收到的json
		String result = "[{\"username\": \"your name\", \"user_json\": {\"username\": \"your name\", \"nickname\": \"your nickname\"}}]";
	 	//根據字符串陳
		//根據字符串生成JSON對象
		//如果是數組的形式 就使用 JSONArray.fromObject(result) 轉化爲JSONArray 對象
		//如果是json對象  就是使用JSONObject.fromObject(result) 轉化爲JSONObject 對象
		JSONArray resultArray = JSONArray.fromObject(result);
		JSONObject jsonObject = resultArray.getJSONObject(0);
		JSONObject user_json = jsonObject.getJSONObject("user_json");
		//根據key值取值
		String username = user_json.getString("username");
		String nickname = user_json.getString("nickname");
		System.out.println("username =" + username  + ":" + "nickname = " + nickname);
		//console ：  username =your name:nickname = your nickname
	}

三 、後臺轉化list 或map轉化爲json形式的字符串傳值到前臺的ajax中

user bean

public class User {
	private String name;
	private Adress adress;
	private List<String> students;
	public String getName() {
		return name;
	}
	public void setName(String name) {
		this.name = name;
	}
	public Adress getAdress() {
		return adress;
	}
	public void setAdress(Adress adress) {
		this.adress = adress;
	}
	public List<String> getStudents() {
		return students;
	}
	public void setStudents(List<String> students) {
		this.students = students;
	}
	public User(String name, Adress adress, List<String> students) {
		super();
		this.name = name;
		this.adress = adress;
		this.students = students;
	}
	public User() {
		super();
	}
	
}

public class Adress {
	private String streetName;
	private String district;
	public String getStreetName() {
		return streetName;
	}
	public void setStreetName(String streetName) {
		this.streetName = streetName;
	}
	public String getDistrict() {
		return district;
	}
	public void setDistrict(String district) {
		this.district = district;
	}
	public Adress(String streetName, String district) {
		super();
		this.streetName = streetName;
		this.district = district;
	}
	public Adress() {
		super();
		// TODO Auto-generated constructor stub
	}
	
}

1）bean to json 

@Test
	public void beanToJson(){
		List list = new ArrayList();
		list.add( "xiaowang" );
		list.add( "xiaohua" );
		Adress adress =  new Adress("streetName", "district");
		JSONObject jsonObject =  JSONObject.fromObject(new User("name", adress, list));
		System.out.println(jsonObject.toString());
		//console ：{"adress":{"district":"district","streetName":"streetName"},"name":"name","students":["xiaowang","xiaohua"]}
	}

2）

	@Test
	public void list2Json(){
		List list = new ArrayList();
		list.add( "first" );
		list.add( "second" );
		JSONArray  jsonArray = JSONArray.fromObject(list);
		System.out.println(jsonArray.toString());
	}
	
	public Map getMap(){
		 //聲明一個Hash對象並添加數據
		 Map params =  new HashMap();
	
		params.put("username", "username");
		params.put("user_json", "user");
		return params;
	}
	@Test
	public void map2Json(){
		Map map = getMap();
		Map map1 = getMap();
		List list = new ArrayList();
		list.add(map);
		list.add(map1);
		JSONArray jsonArray = JSONArray.fromObject(list);
		System.out.println("jsonArray--->" + jsonArray.toString());
		JSONArray jsonArray1 = JSONArray.fromObject(map);
		System.out.println("jsonArray1--->" + jsonArray1.toString());
	}

完整：

      

public class SimpleExample {
	
	@Test
	public void list2Json(){
		List list = new ArrayList();
		list.add( "first" );
		list.add( "second" );
		JSONArray  jsonArray = JSONArray.fromObject(list);
		System.out.println(jsonArray.toString());
	}
	
	public Map getMap(){
		 //聲明一個Hash對象並添加數據
		 Map params =  new HashMap();
	
		params.put("username", "username");
		params.put("user_json", "user");
		return params;
	}
	@Test
	public void map2Json(){
		Map map = getMap();
		Map map1 = getMap();
		List list = new ArrayList();
		list.add(map);
		list.add(map1);
		JSONArray jsonArray = JSONArray.fromObject(list);
		System.out.println("jsonArray--->" + jsonArray.toString());
		JSONArray jsonArray1 = JSONArray.fromObject(map);
		System.out.println("jsonArray1--->" + jsonArray1.toString());
	}
	//根據接收的json字符串來解析字符串中所包含的數據和數據對象
	@Test
	public void parsJsonFromFront(){
		//接收到的json
		String result = "[{\"username\": \"your name\", \"user_json\": {\"username\": \"your name\", \"nickname\": \"your nickname\"}}]";
	 	//根據字符串陳
		//根據字符串生成JSON對象
		//如果是數組的形式 就使用 JSONArray.fromObject(result) 轉化爲JSONArray 對象
		//如果是json對象  就是使用JSONObject.fromObject(result) 轉化爲JSONObject 對象
		JSONArray resultArray = JSONArray.fromObject(result);
		JSONObject jsonObject = resultArray.getJSONObject(0);
		JSONObject user_json = jsonObject.getJSONObject("user_json");
		//根據key值取值
		String username = user_json.getString("username");
		String nickname = user_json.getString("nickname");
		System.out.println("username =" + username  + ":" + "nickname = " + nickname);
		//console ：  username =your name:nickname = your nickname
	}
	
	@Test
	public void beanToJson(){
		List list = new ArrayList();
		list.add( "xiaowang" );
		list.add( "xiaohua" );
		Adress adress =  new Adress("streetName", "district");
		JSONObject jsonObject =  JSONObject.fromObject(new User("name", adress, list));
		System.out.println(jsonObject.toString());
		//console ：{"adress":{"district":"district","streetName":"streetName"},"name":"name","students":["xiaowang","xiaohua"]}
	}
	
}

相關依賴jar下載：http://download.csdn.net/detail/hao007cn/8995465