JSONObject和JSONArray

1.从Object到String

要先用Object对象构造一个JSONObject或者JSONArray对象，然后调用它的toString()方法即可

（1）示例一

Book book=new Book();

book.setName("Java");

book.setPrice(52.3f);

JSONObject object=JSONObject.fromObject(book);

System.out.println(object.toString());

（2）示例二

Book book=new Book();

book.setName("Java");

book.setPrice(52.3f);

Book book2=new Book();

book2.setName("C");

book2.setPrice(42.3f);

List list=new ArrayList();

list.add(book);

list.add(book2);

JSONArray arry=JSONArray.fromObject(list);

System.out.println(arry.toString());

//结果如下：

[{"name":"Java","price":52.3},{"name":"C","price":42.3}]

2.从String到Object

要先用String对象构造一个JSONObject或者JSONArray对象

(1)示例一

1 String json="{name:'Java',price:52.3}";
2 JSONObject object=JSONObject.fromObject(json);
3 System.out.println(object.get("name")+" "+object.get("price"));

(2)示例二
String json="[{name:'Java',price:52.3},{name:'C',price:42.3}]";

JSONArray array=JSONArray.fromObject(json);

for(int i=0;i<array.size();i++){

Map o=(Map)array.get(i);

System.out.println(o.get("name")+" "+o.get("price"));

}

3.从String到Bean

(1)单个Bean对象
String json="{name:'Java',price:52.3}";

JSONObject object=JSONObject.fromObject(json);

Product product=(Product)JSONObject.toBean(object,Product.class);

System.out.println(product.getName()+" "+product.getPrice());

(2).Bean的数组

String json="[{name:'Java',price:52.3},{name:'C',price:42.3}]";

JSONArray array=JSONArray.fromObject(json);

Product[] products=(Product[]) JSONArray.toArray(array,Product.class);

for(Product p:products){

System.out.println(p.getName()+" "+p.getPrice());

}

自定义封装JSON操作的类

public class JsonHelper {

//从普通的Bean转换为字符串

public static String getJson(Object o){

JSONObject jo=JSONObject.fromObject(o);

return jo.toString();

}

//从Java的列表转换为字符串

public static String getJson(List list){

JSONArray ja=JSONArray.fromObject(list);

return ja.toString();

}

//从Java对象数组转换为字符串

public static String getJson(Object[] arry){

JSONArray ja=JSONArray.fromObject(arry);

return ja.toString();

}

//从json格式的字符串转换为Map对象

public static Map getObject(String s){

return JSONObject.fromObject(s);

}

//从json格式的字符串转换为List数组

public static List getArray(String s){

return JSONArray.fromObject(s);

}

//从json格式的字符串转换为某个Bean

public static Object getObject(String s,Class cls){

JSONObject jo=JSONObject.fromObject(s);

return JSONObject.toBean(jo, cls);

}

//从json格式的字符串转换为某类对象的数组

public static Object getArray(String s,Class cls){

JSONArray ja=JSONArray.fromObject(s);

return JSONArray.toArray(ja, cls);

}