JSON 字串 與 java 對象之間互相轉換

標籤：

首先引入maven需要依賴的jar：

<dependency>    <groupId>net.sf.json-lib</groupId>    <artifactId>json-lib</artifactId>    <version>2.4</version>    <classifier>jdk15</classifier></dependency>

需要匯入的類：

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

1. //把java對象列錶轉換為json對象數組，並轉為字串
    JSONArrayarray = JSONArray.fromObject(userlist);    Stringjsonstr = array.toString();
2.//把java對象轉換成json對象，並轉化為字串
  JSONObject object =JSONObject.fromObject(invite);  Log4jInit.ysulogger.debug(object.toString());
3.//把JSON字串轉換為JAVA對象數組
  String personstr =getRequest().getParameter("persons");  JSONArray json =JSONArray.fromObject(personstr);  List<InvoidPerson>persons =(List<InvoidPerson>)JSONArray.toCollection(json,nvoidPerson.class);4.//把JSON字串轉換為JAVA對象
 
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\":\"賀明\",\"passporttype\":\"K\"}]}";   JSONObjectjsonobject = JSONObject.fromObject(str);  PassportLendsEntitypassportlends = null;  try {   //擷取一個json數組   JSONArrayarray = jsonobject.getJSONArray("passports");   //將json數組 轉換成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);           }          }   //轉換PassportLendsEntity實體類   passportlends= (PassportLendsEntity)JSONObject.toBean(jsonobject,PassportLendsEntity.class);
5.如果只想取JSON字串的某幾個欄位，就沒必要轉成Java對象，直接轉成對象數組，再把數組轉成對象，再去某個欄位的值

JSONArray listArray = dataObject.getJSONArray("list");for (int i =0; i < listArray.size(); i++){    tmp = listArray.getJSONObject(i);    float longitude = tmp.getString("longitude");
}

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JSON 字串 與 java 對象之間互相轉換