JAVA-关于JSON解析

JSON:JavascriptObjectNotationJS对象简谱,是一种轻量级的数据交换格式

		JSON格式
        {"name":"伟杰老师",
        "age":18,
        "pengyou":["张三","李四","王二","麻子",{
        		   "name":"野马老师","info":"像匹野马一样狂奔在技术钻研的道路上"}],
        "heihei":{
             "name":"大长刀",
             "length":"40m"
             }
         }

1.1 将Java中的对象快速的转换为JSON格式的字符串

		Gson g = new Gson();
		//一个实体类Book，包含有参构造方法与无参构造方法，三个属性分别为：id,name,info
		Book book = new Book("1233", "gold apple", "金苹果的故事");
		String s = g.toJson(book);
		System.out.println(s);

1.2 将JSON字符串转换为对象

		Gson g = new Gson();
        Book book = g.fromJson("{"id":"1233","name":"gold apple","info":"金苹果	   "}", Book.class);
        String s = g.toJson(book);
        //需要重写toString方法
        System.out.println(book);

1.3 将JSON转换为集合形式

		Gson g = new Gson();
        //{"id":"1233","name":"gold apple","info":"its to hard to make","page":["MON","TUS","WEN"]}
        HashMap h = g.fromJson("{"id":"1233","name":"gold apple","info":"金苹果","page":["MON","TUS","WEN"]}", HashMap.class);
        List list = (List) h.get("page");
        System.out.println(list.get(1));
        System.out.println(h.get("page").getClass());

2.1 将Java中的对象快速的转换为JSON格式的字符串

		Book book = new Book("1234", "zh", "zizhuan");
        String s = JSON.toJSONString(book);
        System.out.println(s);

2.2 将JSON字符串转换为对象

		Book book = JSON.parseObject("{"id":"1233","name":"gold apple","info":"its to hard to make","page":["MON","TUS","WEN"]}", Book.class);
		//有与book没有page属性，则打印book也不会出现。
        System.out.println(book);

        //["123","456","789"]
        List list = JSON.parseArray("["123","456","789"]", String.class);
        System.out.println(list);

2.3 将JSON转换为集合形式

	   	List list = JSON.parseArray("["123","456","789"]", String.class);
        System.out.println(list);