首先引入maven需要依赖的jar：
<dependency>
<groupId>net.sf.json-lib</groupId>
<artifactId>json-lib</artifactId>
<version>2.4</version>
<classifier>jdk15</classifier>
</dependency>
需要导入的类：
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);5.如果只想取JSON字符串的某几个字段，就没必要转成Java对象，直接转成对象数组，再把数组转成对象，再去某个字段的值
JSONArray listArray = dataObject.getJSONArray("list");
for (int i =0; i < listArray.size(); i++){
tmp = listArray.getJSONObject(i);
float longitude = tmp.getString("longitude");}
