import net.sf.json.JSONArray; //用于集合或数组
import net.sf.json.JSONObject; //用于对象
JSONObject object = new JSONObject();
1.把java 对象列表转换为json对象数组，并转为字符串
JSONArray array = JSONArray.fromObject(userlist);
String jsonstr = array.toString();
2.把java对象转换成json对象，并转化为字符串(好像是map)
JSONObject object = JSONObject.fromObject(invite);
String str=object.toString();
3.把JSON字符串转换为JAVA 对象数组
String personstr = getRequest().getParameter("persons");
JSONArray json = JSONArray.fromObject(personstr);
List<InvoidPerison> persons = (List<InvoidPerson>)JSONArray.toCollection(json, nvoidPerson.class);
4.把JSON字符串转换为JAVA 对象
JSONObject jsonobject = JSONObject.fromObject(str);
PassportLendsEntity passportlends = null;
try {
//获取一个json数组
JSONArray array = jsonobject.getJSONArray("passports");
//将json数组 转换成 List<PassPortForLendsEntity>泛型
List<PassPortForLendsEntity> list = new ArrayList<PassPortForLendsEntity>();
for (int i = 0; i < array.size(); i++) {
JSONObject object = (JSONObject)array.get(i);
PassPortForLendsEntity passport = (PassPortForLendsEntity)JSONObject.toBean(object,
PassPortForLendsEntity.class);
if(passport != null){
list.add(passport);
}
}
开发中遇到的问题---【java中常见的JSON格式转换方法】
原文：https://www.cnblogs.com/hujunwei/p/11312692.html