net.sf.json.JSONObject使用

转载自：https://blog.csdn.net/u013514928/article/details/79114814/

JSONObjetc和JSONArray存在多种用法，下面介绍JSONObject和JSONArray的创建、合并以及解析。

import java.util.ArrayList;
import java.util.HashMap;

import net.sf.json.JSONArray;
import net.sf.json.JSONObject;

public class JsonCombine {

    public static void main(String[] args) {
        JSONObject jsonOne = new JSONObject();
        jsonOne.put("name", "kewen");
        jsonOne.put("age", "24");
        JSONObject jsonTwo = new JSONObject();
        jsonTwo.put("hobbit", "Doto");
        jsonTwo.put("hobbit2", "wow");
        JSONObject jsonThree = new JSONObject();
        jsonThree.putAll(jsonOne);
        jsonThree.putAll(jsonTwo);
        System.out.println(jsonThree.toString());

        // JsonObject和JsonArray区别就是JsonObject是对象形式，JsonArray是数组形式
        // 创建JsonObject第一种方法
        JSONObject jsonObject = new JSONObject();
        jsonObject.put("UserName", "ZHULI");
        jsonObject.put("age", "30");
        jsonObject.put("workIn", "ALI");
        System.out.println("jsonObject1：" + jsonObject);

        // 创建JsonObject第二种方法
        HashMap hashMap = new HashMap();
        hashMap.put("UserName", "ZHULI");
        hashMap.put("age", "30");
        hashMap.put("workIn", "ALI");
        System.out.println("jsonObject2：" + JSONObject.fromObject(hashMap));

        // 创建一个JsonArray方法1
        JSONArray jsonArray = new JSONArray();
        jsonArray.add(0, "ZHULI");
        jsonArray.add(1, "30");
        jsonArray.add(2, "ALI");
        System.out.println("jsonArray1：" + jsonArray);

        // 创建JsonArray方法2
        ArrayList arrayList = new ArrayList();
        arrayList.add("ZHULI");
        arrayList.add("30");
        arrayList.add("ALI");
        System.out.println("jsonArray2：" + JSONArray.fromObject(arrayList));
        // 如果JSONArray解析一个HashMap
        System.out.println("jsonArray FROM HASHMAP：" + JSONArray.fromObject(hashMap));
        // 组装一个复杂的JSONArray
        JSONObject jsonObject2 = new JSONObject();
        jsonObject2.put("UserName", "ZHULI");
        jsonObject2.put("age", "30");
        jsonObject2.put("workIn", "ALI");
        jsonObject2.element("Array", arrayList);
        jsonObject2.element("Map", hashMap);
        System.out.println("jsonObject2：" + jsonObject2);

        // 将Json字符串转为java对象
        String jsonString = "{\"UserName\":\"ZHULI\",\"age\":\"30\",\"workIn\":\"ALI\",\"Array\":[\"ZHULI\",\"30\",\"ALI\"]}";
        JSONObject obj = JSONObject.fromObject(jsonString);
        if (obj.has("UserName")) {
            System.out.println("UserName:" + obj.getString("UserName"));
        }
        if (obj.has("Array")) {
            JSONArray transitListArray = obj.getJSONArray("Array");
            for (int i = 0; i < transitListArray.size(); i++) {
                System.out.println("Array:" + transitListArray.getString(i) + " ");

            }
        }

    }

}

       运行结果：

{"name":"kewen","age":"24","hobbit":"Doto","hobbit2":"wow"}
jsonObject1：{"UserName":"ZHULI","age":"30","workIn":"ALI"}
jsonObject2：{"UserName":"ZHULI","workIn":"ALI","age":"30"}
jsonArray1：["ZHULI","30","ALI"]
jsonArray2：["ZHULI","30","ALI"]
jsonArray FROM HASHMAP：[{"UserName":"ZHULI","workIn":"ALI","age":"30"}]
jsonObject2：{"UserName":"ZHULI","age":"30","workIn":"ALI","Array":["ZHULI","30","ALI"],"Map":{"UserName":"ZHULI","workIn":"ALI","age":"30"}}
UserName:ZHULI
Array:ZHULI
Array:30
Array:ALI

optXX（key，defaultValue）区别于getXX(key) ，getXX(key)如果不存在key会抛出异常,

optXX()会返回defafltValue

上代码：

String jsonStr="{\"name\":\"xy\",\"age\":24}";
		JSONObject  json= JSONObject.fromObject(jsonStr);
		System.out.println("json.opt(name)---"+json.opt("name"));
		System.out.println("json.optInt(age, 22)---"+json.optInt("age", 22));
		System.out.println("json.optString(age)---"+json.optString("age"));
		System.out.println("json.opt(aaa)---"+json.opt("aaa"));

执行结果：

json.opt(name)---xy
json.optInt(age, 22)---24
json.optString(age)---24
json.opt(aaa)---null