Converting JSON strings to Java objects

First, the jar that Maven needs to rely on is introduced:

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

Classes that need to be imported:

Import Net.sf.json.JSONArray;
Import Net.sf.json.JSONObject;

1.//Convert the list of Java objects to a JSON object array and turn to a string
  jsonarrayarray = Jsonarray.fromobject (userlist);       stringjsonstr = array.tostring (  );
2.//Converts a Java object into a JSON object and converts it into a string
Jsonobject Object = Jsonobject.fromobject (invite);     Log4jInit.ysulogger.debug (object.tostring ()  );
3.//converting a JSON string to an array of Java objects
 String personstr =getrequest (). GetParameter ("persons");  jsonarray json =jsonarray.fromobject (personstr  ); list<invoidperson>persons = (list<invoidperson>)jsonarray.tocollection  ( Json,nvoidperson.class); 4.//to convert a JSON string to a Java object
 
str = "{\" lendperson\ ": \" John Doe \ ", \" lendcompany\ ": \" limited \ ", \" checkperson\ ": \" John Doe \ ", \ "lenddate\": \ "2010-07-19t00:00:00\", \ "lendcounts\": 4,\ "Passports\ ": [{\" passportid\ ": \" d\ ", \" name\ ": \" Li Shuichang \ ", \" passporttype\ ": \" K\ "},{\ "passportid\": \ "k9051\", \ "name\": \ "Li ping \", \ "passporttype\": \ "K\"},{\ "passportid\": \ "k90517\", \ "name\": \ "Yuan Han mei \", \ "passporttype\": \ "K\"},{\ "passportid\": \ "k905199\", \ "name\": \ "He Ming \", \ "passporttype\": \ "K\"}]} ";Jsonobjectjsonobject = Jsonobject.fromobject (str);Passportlendsentitypassportlends = null;try {Get a JSON arrayJsonarrayarray = Jsonobject.getjsonarray ("passports");Convert JSON arrays to list<passportforlendsentity> genericsList<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);}}Convert passportlendsentity entity classPassportlends= (passportlendsentity)Jsonobject.tobean(Jsonobject,passportlendsentity.class);
5. If you want to take only a few fields of the JSON string, there is no need to turn into a Java object, go directly to an object array, then convert the array to an object, then go to the value of a field

Jsonarray Listarray = Dataobject.getjsonarray ("list");  (i =0; i < listarray.size (); i++) {    tmp = Listarray.getjsonobject (i);    float longitude = tmp.getstring ("longitude");
}

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Converting JSON strings to Java objects