Wednesday, July 6, 2011

Parse JSON returned from Flickr Services

Further work on the last exercise "Access Flickr API using HttpClient", a method ParseJSON() is implemented to parse the JSON returned from Flickr Services.

Parse JSON returned from Flickr Services

package com.exercise.AndroidFlickr;


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;

import org.apache.http.HttpEntity;
import org.apache.http.client.ClientProtocolException;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class AndroidFlickrActivity extends Activity {

/*
* FlickrQuery = FlickrQuery_url
* + FlickrQuery_per_page
* + FlickrQuery_nojsoncallback
* + FlickrQuery_format
* + FlickrQuery_tag + q
* + FlickrQuery_key + FlickrApiKey
*/

String FlickrQuery_url = "http://api.flickr.com/services/rest/?method=flickr.photos.search";
String FlickrQuery_per_page = "&per_page=1";
String FlickrQuery_nojsoncallback = "&nojsoncallback=1";
String FlickrQuery_format = "&format=json";
String FlickrQuery_tag = "&tags=";
String FlickrQuery_key = "&api_key=";

// Apply your Flickr API:
// www.flickr.com/services/apps/create/apply/?
String FlickrApiKey = "2155e9406043b7494453105eec99ae37";

EditText searchText;
Button searchButton;
TextView textQueryResult, textJsonResult;

/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);

searchText = (EditText)findViewById(R.id.searchtext);
searchButton = (Button)findViewById(R.id.searchbutton);
textQueryResult = (TextView)findViewById(R.id.queryresult);
textJsonResult = (TextView)findViewById(R.id.jsonresult);

searchButton.setOnClickListener(searchButtonOnClickListener);
}

private Button.OnClickListener searchButtonOnClickListener
= new Button.OnClickListener(){

public void onClick(View arg0) {
// TODO Auto-generated method stub
String searchQ = searchText.getText().toString();
String searchResult = QueryFlickr(searchQ);
textQueryResult.setText(searchResult);
String jsonResult = ParseJSON(searchResult);
textJsonResult.setText(jsonResult);
}};

private String QueryFlickr(String q){

String qResult = null;

String qString =
FlickrQuery_url
+ FlickrQuery_per_page
+ FlickrQuery_nojsoncallback
+ FlickrQuery_format
+ FlickrQuery_tag + q
+ FlickrQuery_key + FlickrApiKey;

HttpClient httpClient = new DefaultHttpClient();
HttpGet httpGet = new HttpGet(qString);

try {
HttpEntity httpEntity = httpClient.execute(httpGet).getEntity();

if (httpEntity != null){
InputStream inputStream = httpEntity.getContent();
Reader in = new InputStreamReader(inputStream);
BufferedReader bufferedreader = new BufferedReader(in);
StringBuilder stringBuilder = new StringBuilder();

String stringReadLine = null;

while ((stringReadLine = bufferedreader.readLine()) != null) {
stringBuilder.append(stringReadLine + "\n");
}

qResult = stringBuilder.toString();

}

} catch (ClientProtocolException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

return qResult;
}

private String ParseJSON(String json){

String jResult = null;

try {
JSONObject JsonObject = new JSONObject(json);
JSONObject Json_photos = JsonObject.getJSONObject("photos");
JSONArray JsonArray_photo = Json_photos.getJSONArray("photo");

//We have only one photo in this exercise
JSONObject FlickrPhoto = JsonArray_photo.getJSONObject(0);

jResult = "\nid: " + FlickrPhoto.getString("id") + "\n"
+ "owner: " + FlickrPhoto.getString("owner") + "\n"
+ "secret: " + FlickrPhoto.getString("secret") + "\n"
+ "server: " + FlickrPhoto.getString("server") + "\n"
+ "farm: " + FlickrPhoto.getString("farm") + "\n"
+ "title: " + FlickrPhoto.getString("title") + "\n";

} catch (JSONException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}

return jResult;

}
}


Modify main.xml to add a TextView, jsonresult, to display the parsed JSON data.
<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="@string/hello"
/>
<EditText
android:id="@+id/searchtext"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<Button
android:id="@+id/searchbutton"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Search"
/>
<TextView
android:id="@+id/queryresult"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
<TextView
android:id="@+id/jsonresult"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
/>
</LinearLayout>


next:
- Load photo from Flickr

Related article:
- Get Time Zone of location, from web service of www.geonames.org


3 comments:

Serj said...

Mmm can u help me? I can't understand how to parse json type like this:

[
{
"id": 12,
"name": 12,
"status": "ok",
"volumes": [
{
"id": 17592,
"name": "root",
"status": "ok"
},
}
]

As you can see there is no named object at beginning, it's array with values 0,1,3 with subarray

Android Er said...

hello Serj,

I think your JSON should be: {"id":12,"name":12,"status":"ok","volumes":[{"id":17592,"name":"root","status":"ok"}]}

Please read: Another example to parse JSON

Serj said...

Unfortunately I use the API provides an array of objects, my previous json not right, i edit it for e.g. I'm trying to figure out this json by myself. But the example of the output of this api can give a in a private.