I would like to send messages in the form of JSON objects to a server and parse the JSON response from the server.
Example of JSON object
{
"post": {
"username": "John Doe",
"message": "test message",
"image": "image url",
"time": "current time"
}
}
I am trying to parse the JSON manually by going attribute by attribute. Is there any library/utility I can use to make this process easier?
if your are looking for fast json parsing in android than i suggest you a tool which is freely available.
It's free to use and it's create your all json parsing class within a one-two seconds.. :D
There are different open source libraries, which you can use for parsing json.
org.json :- If you want to read or write json then you can use this library. First create JsonObject :-
JSONObject jsonObj = new JSONObject(<jsonStr>);
Now, use this object to get your values :-
String id = jsonObj.getString("id");
You can see complete example here
Jackson databind :- If you want to bind and parse your json to particular POJO class, then you can use jackson-databind library, this will bind your json to POJO class :-
ObjectMapper mapper = new ObjectMapper();
post= mapper.readValue(json, Post.class);
You can see complete example here
You can use org.json.JSONObject and org.json.JSONTokener. you don't need any external libraries since these classes come with Android SDK
You can download a library from http://json.org (Json-lib or org.json) and use it to parse/generate the JSON
Although there are already excellent answers are provided by users such as encouraging use of GSON etc. I would like to suggest use of org.json. It includes most of GSON functionalities. It also allows you to pass json string as an argument to it's JSONObject and it will take care of rest e.g:
JSONObject json = new JSONObject("some random json string");
This functionality make it my personal favorite.
This is the JsonParser class
public class JSONParser {
static InputStream is = null;
static JSONObject jObj = null;
static String json = "";
// constructor
public JSONParser() {
}
public JSONObject getJSONFromUrl(String url) {
// Making HTTP request
try {
// defaultHttpClient
DefaultHttpClient httpClient = new DefaultHttpClient();
HttpPost httpPost = new HttpPost(url);
HttpResponse httpResponse = httpClient.execute(httpPost);
HttpEntity httpEntity = httpResponse.getEntity();
is = httpEntity.getContent();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (ClientProtocolException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}
try {
BufferedReader reader = new BufferedReader(new InputStreamReader(
is, "iso-8859-1"), 8);
StringBuilder sb = new StringBuilder();
String line = null;
while ((line = reader.readLine()) != null) {
sb.append(line + "\n");
}
is.close();
json = sb.toString();
} catch (Exception e) {
Log.e("Buffer Error", "Error converting result " + e.toString());
}
// try parse the string to a JSON object
try {
jObj = new JSONObject(json);
} catch (JSONException e) {
Log.e("JSON Parser", "Error parsing data " + e.toString());
}
// return JSON String
return jObj;
}
Note: DefaultHttpClient is no longer supported by sdk 23, so it is advisable to use target sdk 21 with this code.
you just need to import this
import org.json.JSONObject;
constructing the String that you want to send
JSONObject param=new JSONObject();
JSONObject post=new JSONObject();
im using two object because you can have an jsonObject within another
post.put("username(here i write the key)","someusername"(here i put the value);
post.put("message","this is a sweet message");
post.put("image","http://localhost/someimage.jpg");
post.put("time": "present time");
then i put the post json inside another like this
param.put("post",post);
this is the method that i use to make a request
makeRequest(param.toString());
public JSONObject makeRequest(String param)
{
try
{
setting the connection
urlConnection = new URL("your url");
connection = (HttpURLConnection) urlConnection.openConnection();
connection.setDoOutput(true);
connection.setRequestMethod("POST");
connection.setRequestProperty("Content-type", "application/json;charset=UTF-8");
connection.setReadTimeout(60000);
connection.setConnectTimeout(60000);
connection.connect();
setting the outputstream
dataOutputStream = new DataOutputStream(connection.getOutputStream());
i use this to see in the logcat what i am sending
Log.d("OUTPUT STREAM " ,param);
dataOutputStream.writeBytes(param);
dataOutputStream.flush();
dataOutputStream.close();
InputStream in = new BufferedInputStream(connection.getInputStream());
BufferedReader reader = new BufferedReader(new InputStreamReader(in));
result = new StringBuilder();
String line;
here the string is constructed
while ((line = reader.readLine()) != null)
{
result.append(line);
}
i use this log to see what its comming in the response
Log.d("INPUTSTREAM: ",result.toString());
instancing a json with the String that contains the server response
jResponse=new JSONObject(result.toString());
}
catch (IOException e) {
e.printStackTrace();
return jResponse=null;
} catch (JSONException e)
{
e.printStackTrace();
return jResponse=null;
}
connection.disconnect();
return jResponse;
}
GSON is easiest to use and the way to go if the data have a definite structure.
Download gson.
Add it to the referenced libraries.
package com.tut.JSON;
import org.json.JSONException;
import org.json.JSONObject;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
public class SimpleJson extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
String jString = "{\"username\": \"tom\", \"message\": \"roger that\"} ";
GsonBuilder gsonb = new GsonBuilder();
Gson gson = gsonb.create();
Post pst;
try {
pst = gson.fromJson(jString, Post.class);
} catch (JSONException e) {
e.printStackTrace();
}
}
}
Code for Post class
package com.tut.JSON;
public class Post {
String message;
String time;
String username;
Bitmap icon;
}
There's not really anything to JSON. Curly brackets are for "objects" (associative arrays) and square brackets are for arrays without keys (numerically indexed). As far as working with it in Android, there are ready made classes for that included in the sdk (no download required).
Check out these classes: http://developer.android.com/reference/org/json/package-summary.html
Other answers have noted Jackson and GSON - the popular add-on JSON libraries for Android, and json.org, the bare-bones JSON package that is included in Android.
But I think it is also worth noting that Android now has its own full featured JSON API.
This was added in Honeycomb: API level 11.
This comprises
- android.util.JsonReader: docs, and source
- android.util.JsonWriter: docs, and source
I will also add one additional consideration that pushes me back towards Jackson and GSON: I have found it useful to use 3rd party libraries rather then android.* packages because then the code I write can be shared between client and server. This is particularly relevant for something like JSON, where you might want to serialize data to JSON on one end for sending to the other end. For use cases like that, if you use Java on both ends it helps to avoid introducing android.* dependencies.
Or I guess one could grab the relevant android.* source code and add it to your server project, but I haven't tried that...
Source: Stackoverflow.com