区别

JSONObject的数据是用 { } 来表明的，

    例如：   { "id" :1, "name" : "张一"}  

JSONArray，是由JSONObject构成的数组，用 [ { } , { } , …… , { } ] 来表明

   例如：   [ { "id" :1, "name" : "张一"}, { "id" :2, "name" : "张二"}] ； 

用法

people类

@Data
public class People {
    private Integer id;
    private String name;

    public People(Integer id, String name) {
        this.id = id;
        this.name = name;
    }
}

对象、JSON字符串相互转换

People people = new People(1, "张一");
 //对象转String
String people2String = JSONObject.toJSONString(people);
 //String转对象
People string2People = JSONObject.parseObject(people2String, People.class); 

对象、JSONObject相互转换

People people = new People(1, "张一");
//对象转JSONObject
JSONObject people2JsonObject = (JSONObject) JSONObject.toJSON(people);
//JSONObject转对象
People jsonObject2People = JSONObject.toJavaObject(people2JsonObject, People.class);

List、对象相互转换

List<People> peopleList = new ArrayList<>();
peopleList.add(pnew People(2, "张一);
peopleList.add(new People(2, "张二"));
peopleList.add(new People(3, "张三"));

//List转JSONArray
JSONArray peoples2JsonArray = JSONArray.parseArray(JSON.toJSONString(peopleList));
//JSONArray转List
List<People> jsonArray2Peoples = JSONObject.parseArray(peoples2JsonArray.toJSONString(), People.class);


//List转String
String peoples2String = JSONArray.toJSONString(peopleList);
//String转List
List<People> string2Peoples = JSONObject.parseArray(peoples2String, People.class);

JSONArray循环遍历

方法一

 List<People> peopleLists = new ArrayList<>();
 for (int i = 0; i < jsonArray.size(); i++) {
    JSONObject peopleJsonObject = peoples2JsonArray.getJSONObject(i);
    People peopleOne = new People(peopleJsonObject.getInteger("id"), peopleJsonObject.getString("name"));
    peopleLists.add(peopleOne);
}

方法二

List<People> peopleLists = new ArrayList<>();
Iterator<Object> it = peoples2JsonArray.iterator();
List<JSONObject> list = new ArrayList<JSONObject>();
while (it.hasNext()) {
    JSONObject jsonObj = (JSONObject) it.next();
    People peopleOne = new People(jsonObj.getInteger("id"),  jsonObj.getString("name"));
    peopleLists.add(peopleOne);
}

遍历JSONObject

People people = new People(1, "张一");
JSONObject people2JsonObject = (JSONObject) JSONObject.toJSON(people);
for (Map.Entry entry : people2JsonObject.entrySet()) {
    System.out.println(entry.getValue());
}

输出结果

1
张一