Android: parse JSON using gon

Android provides JSON parsing, but its jsonreader SDK is available after 3.0.

Its resolution method can refer to the http://developer.android.com/reference/android/util/JsonReader.html

 

For earlier versions, we can use some additional packages to facilitate resolution.

Use gson package

Com. Google. gson. Stream. jsonreader

: Http://code.google.com/p/google-gson/downloads/list

DocumentDocs:Http://google-gson.googlecode.com/svn/trunk/gson/docs/javadocs/index.html
For example, the data to be parsed is

String jsondata = "[{\" Name \ ": \" Michael \ ", \" Age \ ": 20 },{ \" Name \ ": \" Mike \", \ "Age \": 21}] ";

The parsing method can be as follows:

         Try  {  //  To parse JSON data, you must first generate a jsonreader object. Jsonreader reader = New Jsonreader ( New  Stringreader (jsondata); reader. beginarray ();  While  (Reader. hasnext () {reader. beginobject (); While  (Reader. hasnext () {string tagname = Reader. nextname ();  If (Tagname. Equals ("name" ) {System. Out. println ( "Name --->" + Reader. nextstring ());}  Else   If (Tagname. Equals ("Age" ) {System. Out. println ( "Age --->" +Reader. nextint ();} reader. endobject ();} reader. endarray ();}  Catch  (Exception e) {e. printstacktrace ();} 

 

Parses a JSON object to a custom objectFor example:

To parse string jsondata = "{\" Name \ ": \" Michael \ ", \" Age \ ": 20 }";

Users of the model class can be defined.

 Public   Class  User {  Private  String name;  Private  Int  Age;  Public  String getname (){  Return  Name ;}  Public   Void  Setname (string name ){  This . Name = Name ;}  Public   Int  Getage (){  Return Age ;}  Public   Void Setage ( Int  Age ){  This . Age = Age ;}} 

Resolution Process:

 
Gson =NewGson (); User user= Gson. fromjson (jsondata, user.Class); System. Out. println ("Name --->" +User. getname (); system. Out. println ("Age ---->" + User. getage ());
 

Supplement:The JSON data to be parsed is as follows:

 

 
{Alist: [{A1:1, A2:2, A3:3}, {A1:11, A2:22, A3:33}], Blist: [{B1:1, B2:2, B3:3}, {B1:11, B2:22, B3:33}], C:0}
 

 

Custom objects are as follows:

 

 Public class model {private list <A> Alist; private list <B> Blist; private  Int  C; public class A {private  Int  A1; private  Int  A2; private  Int  A3;...} public class B {private  Int  B1; private  Int B2; private  Int  B3 ;.........}........}  //  Get set is omitted. 

 

 

 

 

Parses a set of JSON objects to custom objects.

For example, the data to be parsed is:

String jsondata = "[{\" Name \ ": \" Michael \ ", \" Age \ ": 20 },{ \" Name \ ": \" Mike \", \ "Age \": 21}] ";

Resolved to the user, which is defined as above,

The parsing process is

     Public  Void  Parseuserfromjson (string jsondata) {type listtype = New Typetoken <shortlist <user> () {}. GetType (); gson = New  Gson (); writable list <User> Users = Gson. fromjson (jsondata, listtype );  //  Traverse users with iterator          For (Iterator = Users. iterator (); iterator. hasnext ();) {user =(User) iterator. Next (); system. Out. println ( "Name --->" + User. getname (); system. Out. println ( "Age ---->" + User. getage ());} 

And check it: http://stackoverflow.com/questions/2779251/convert-json-to-hashmap-using-gson-in-java

 

Object --> JSON

 

Assume that we have a class person:

 

Public class person {

Public long ID;

Public string name;

Public Boolean ismale;

Public String Avatar;

}

 

Use a gson instance:

 

Gson = new gson ();

 

We can directly convert a person instance into a JSON string:

 

Person = new person ();

Person. ID = 111;

Person. Name = "James ";

Person. ismale = true;

Person. Avatar = "http: // aaaaaaaaa ";

 

String jsonstr = gson. tojson (person );

Log. V ("================", jsonstr );

 

Even list and map can be used (taking list as an example ):

 

Arraylist <person> List = new arraylist <person> ();

 

Person = new person ();

Person. ID = 111;

Person. Name = "James ";

Person. ismale = true;

Person. Avatar = "http: // aaaaaaaaa ";

List. Add (person );

Person = new person ();

Person. ID = 222;

Person. Name = "Li Si ";

Person. ismale = false;

Person. Avatar = "http: // bbbbbbbbbbb ";

List. Add (person );

 

String jsonstr = gson. tojson (list );

Log. V ("================", list );

 

See: http://iandroiddev.com/post/2011-10-08/5647743