JSON字符串与java对象的转换

// 引入相应的包

//json-lib-2.2-jdk15.jar

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

1. //把java对象列表转换为json对象数组，并转为字符串

    JSONArrayarray = JSONArray.fromObject(userlist);
    Stringjsonstr = array.toString();

2.//把java对象转换成json对象，并转化为字符串

  JSONObject object =JSONObject.fromObject(invite);
  Log4jInit.ysulogger.debug(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<InvoidPerson>persons =(List<InvoidPerson>)JSONArray.toCollection(json,nvoidPerson.class);
4.//把JSON字符串转换为JAVA对象

  str ="{\"lendperson\":\"李四\",\"lendcompany\":\"有限公司\",\"checkperson\":\"李四\",
  \"lenddate\":\"2010-07-19T00:00:00\",\"lendcounts\":4,\"
  passports\":[{\"passportid\":\"d\",\"name\":\"李豫川\",\"passporttype\":\"K\"},
  {\"passportid\":\"K9051\",\"name\":\"李平\",\"passporttype\":\"K\"},
  {\"passportid\":\"K90517\",\"name\":\"袁寒梅\",\"passporttype\":\"K\"},
  {\"passportid\":\"K905199\",\"name\":\"贺明\",\"passporttype\":\"K\"}]}";
   JSONObjectjsonobject = JSONObject.fromObject(str);
  PassportLendsEntitypassportlends = null;
  try {
   //获取一个json数组
   JSONArrayarray = jsonobject.getJSONArray("passports");
   //将json数组 转换成List<PassPortForLendsEntity>泛型
   List<PassPortForLendsEntity>list = newArrayList<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);
           }  
        }
   //转换PassportLendsEntity实体类
   passportlends= (PassportLendsEntity)JSONObject.toBean(jsonobject,PassportLendsEntity.class);