ตัวอย่างการทำ ListView อ่านข้อมูล JSON ด้วย GSon

{
status: "ok",
count: 10,
count_total: 1732,
pages: 174,
    posts: [
        {
            id: 23479,
            url: "http://blog.teamtreehouse.com/voodoo-responsive-tables-javascript-graphs-treehouse-show-episode-90",
            title: "Voodoo, Responsive Tables, JavaScript Graphs | The Treehouse Show Episode 90",
            date: "2014-05-13 18:02:54",
            author: "Jason Seifer",
            thumbnail: null
        },
        {
            id: 23432,
            url: "http://blog.teamtreehouse.com/working-home-3-tips-staying-task",
            title: "Working from Home? 3 Tips to Staying on Task",
            date: "2014-05-13 08:00:05",
            author: "Theresa Cramer",
            thumbnail: "http://blog.teamtreehouse.com/wp-content/uploads/2014/05/Computer-Desk-David-Martyn-Hunt-Flick-150x150.jpg"
        },
            ....
    ]
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ListView
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:id="@+id/listView" />

</RelativeLayout>

public static final String URL =
        "http://blog.teamtreehouse.com/api/get_recent_summary/";

private class SimpleTask extends AsyncTask<String, Void, String> {

    @Override
    protected void onPreExecute() {
        // Create Show ProgressBar
    }

    protected String doInBackground(String... urls)   {
        String result = "";
        try {

            HttpGet httpGet = new HttpGet(urls[0]);
            HttpClient client = new DefaultHttpClient();

            HttpResponse response = client.execute(httpGet);

            int statusCode = response.getStatusLine().getStatusCode();

            if (statusCode == 200) {
                InputStream inputStream = response.getEntity().getContent();
                BufferedReader reader = new BufferedReader
                        (new InputStreamReader(inputStream));
                String line;
                while ((line = reader.readLine()) != null) {
                    result += line;
                }
            }

        } catch (ClientProtocolException e) {

        } catch (IOException e) {

        }
        return result;
    }

    protected void onPostExecute(String jsonString)  {
        // Dismiss ProgressBar
        showData(jsonString);
    }
}

new SimpleTask().execute(URL);

private void showData(String jsonString) {
    Toast.makeText(this, jsonString, Toast.LENGTH_LONG).show();
}

<uses-permission android:name="android.permission.INTERNET" />

package com.devahoy.sample.ahoygson;

import android.os.AsyncTask;
import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;
import android.widget.Toast;

import org.apache.http.HttpResponse;
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 java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

public class MainActivity extends ActionBarActivity {

    public static final String URL =
            "http://blog.teamtreehouse.com/api/get_recent_summary/";

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        new SimpleTask().execute(URL);
    }

    private class SimpleTask extends AsyncTask<String, Void, String> {

        @Override
        protected void onPreExecute() {
            // Create Show ProgressBar
        }

        protected String doInBackground(String... urls)   {
            String result = "";
            try {

                HttpGet httpGet = new HttpGet(urls[0]);
                HttpClient client = new DefaultHttpClient();

                HttpResponse response = client.execute(httpGet);

                int statusCode = response.getStatusLine().getStatusCode();

                if (statusCode == 200) {
                    InputStream inputStream = response.getEntity().getContent();
                    BufferedReader reader = new BufferedReader
                            (new InputStreamReader(inputStream));
                    String line;
                    while ((line = reader.readLine()) != null) {
                        result += line;
                    }
                }

            } catch (ClientProtocolException e) {

            } catch (IOException e) {

            }
            return result;
        }

        protected void onPostExecute(String jsonString)  {
            // Dismiss ProgressBar
            showData(jsonString);
        }
    }

    private void showData(String jsonString) {
        Toast.makeText(this, jsonString, Toast.LENGTH_LONG).show();
    }

apply plugin: 'android'

android {
    ...
}

dependencies {
    ...
    compile 'com.google.code.gson:gson:2.2.4'
}

import com.google.gson.Gson;

{
	status: "ok",
	count: 10,
	count_total: 1900,
	pages: 190,
	posts: [
		{
			id: 24453,
			url: "http://blog.teamtreehouse.com/havent-started-programming-yet",
			title: "The Real Reason Why Everyone Should Learn to Code",
			date: "2014-11-20 08:30:48",
			author: "Dave McFarland",
			thumbnail: "http://blog.teamtreehouse.com/wp-content/uploads/2014/11/Screen-Shot-2014-11-18-at-11.15.00-AM-150x150.png"
		},
		{
			id: 24462,
			url: "http://blog.teamtreehouse.com/css-shapes",
			title: "CSS Shapes",
			date: "2014-11-19 12:13:20",
			author: "Jason Seifer",
			thumbnail: "http://blog.teamtreehouse.com/wp-content/uploads/2014/11/Getting-Started-with-CSS-Shapes-Wrapping-content-around-custom-paths-HTML5-Rocks-2014-11-19-12-11-51-150x150.jpg"
		},
		...
	]
}

public class Post {
    int id;
    String url;
    String title;
    String date;
    String author;
    String thumbnail;

// Getter and Setter
}

public class Blog {
    String status;

    int count;

    @SerializedName("count_total")
    int totalCount;

    int pages;

    List<Post> posts;

    // Getter and Setter
}

private void showData(String jsonString) {
    Gson gson = new Gson();
    Blog blog = gson.fromJson(jsonString, Blog.class);


    StringBuilder builder = new StringBuilder();
    builder.setLength(0);

    List<Post> posts = blog.getPosts();

    for (Post post : posts) {
        builder.append(post.getTitle());
        builder.append("\n\n");
    }

    Toast.makeText(this, builder.toString(), Toast.LENGTH_LONG).show();
}

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent">


    <ImageView
        android:layout_width="64dp"
        android:layout_height="64dp"
        android:layout_marginRight="8dp"
        android:id="@+id/post_thumbnail"
        android:src="@drawable/ic_launcher"
        android:layout_alignParentTop="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Title"
        android:textSize="16sp"
        android:textStyle="bold"
        android:layout_marginTop="8dp"
        android:id="@+id/post_title"
        android:layout_alignParentTop="true"
        android:layout_toRightOf="@+id/post_thumbnail"/>
    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Author Name"
        android:id="@+id/post_author"
        android:layout_marginTop="8dp"
        android:layout_below="@+id/post_title"
        android:layout_alignLeft="@+id/post_title"
        android:layout_alignStart="@+id/post_title"/>
    <TextView android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:text="Date"
              android:id="@+id/post_date"
              android:layout_marginRight="8dp"
              android:layout_alignTop="@+id/post_author"
              android:layout_alignParentRight="true"
              android:layout_alignParentEnd="true"/>
</RelativeLayout>

package com.devahoy.sample.ahoygson;

import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;

public class CustomAdapter extends BaseAdapter {
    @Override
    public int getCount() {
        return 0;
    }

    @Override
    public Object getItem(int position) {
        return null;
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        return null;
    }
}

public class CustomAdapter extends BaseAdapter {
    private LayoutInflater mInflater;
    List<Post> mPosts;

    public CustomAdapter(Activity activity, List<Post> posts) {
        mInflater = (LayoutInflater) activity.getSystemService(
                Context.LAYOUT_INFLATER_SERVICE);
        mPosts = posts;
    }
    ...
}

@Override
public int getCount() {
    return mPosts.size();
}

@Override
public Object getItem(int position) {
    return mPosts.get(position);
}

@Override
public long getItemId(int position) {
    return position;
}

private static class ViewHolder {
    ImageView thumbnail;
    TextView title;
    TextView author;
    TextView date;
}

@Override
public View getView(int position, View convertView, ViewGroup parent) {

    if (convertView == null) {
        convertView = mInflater.inflate(R.layout.post, parent, false);
        mViewHolder = new ViewHolder();
        mViewHolder.thumbnail = (ImageView) convertView.findViewById(R.id.post_thumbnail);
        mViewHolder.author = (TextView) convertView.findViewById(R.id.post_author);
        mViewHolder.title = (TextView) convertView.findViewById(R.id.post_title);
        mViewHolder.date = (TextView) convertView.findViewById(R.id.post_date);

        convertView.setTag(mViewHolder);

    } else {
        mViewHolder = (ViewHolder) convertView.getTag();
    }

    return convertView;
}

private ViewHolder mViewHolder;

public class MainActivity extends ActionBarActivity {

    public static final String URL =
            "http://blog.teamtreehouse.com/api/get_recent_summary/";

    private ListView mListView;
    private CustomAdapter mAdapter;
    ...

}

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mListView = (ListView) findViewById(R.id.listView);

    new SimpleTask().execute(URL);
}

private void showData(String jsonString) {
    Gson gson = new Gson();
    Blog blog = gson.fromJson(jsonString, Blog.class);
    List<Post> posts = blog.getPosts();

    mAdapter = new CustomAdapter(this, posts);
    mListView.setAdapter(mAdapter);
}

Post post = mPosts.get(position);

mViewHolder.author.setText(post.getAuthor());
mViewHolder.title.setText(post.title);
mViewHolder.date.setText(post.date);

public class CustomAdapter extends BaseAdapter {
    private LayoutInflater mInflater;
    private List<Post> mPosts;
    private ViewHolder mViewHolder;

    private Bitmap mBitmap;
    private Post mPost
    ....
    ....

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        ...

        if (mPost.getThumbnail() != null) {
                new AsyncTask<Void, Void, Void>() {
                    @Override
                    protected Void doInBackground(Void... params) {
                        try {
                            URL url = new URL(mPost.getThumbnail());
                            mBitmap = BitmapFactory.decodeStream(url.openConnection().getInputStream());

                        } catch (MalformedURLException e) {

                        } catch (IOException e) {

                        }
                        return null;
                    }
                }.execute();


            mViewHolder.thumbnail.setImageBitmap(mBitmap);
            ...
            ...
    }
}

@Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.post, parent, false);
            mViewHolder = new ViewHolder();
            mViewHolder.thumbnail = (ImageView) convertView.findViewById(R.id.post_thumbnail);
            mViewHolder.author = (TextView) convertView.findViewById(R.id.post_author);
            mViewHolder.title = (TextView) convertView.findViewById(R.id.post_title);
            mViewHolder.date = (TextView) convertView.findViewById(R.id.post_date);

            convertView.setTag(mViewHolder);

        } else {
            mViewHolder = (ViewHolder) convertView.getTag();
        }


        mPost = mPosts.get(position);

        if (mPost.getThumbnail() != null) {

            new AsyncTask<Void, Void, Void>() {
                @Override
                protected Void doInBackground(Void... params) {
                    try {
                        URL url = new URL(mPost.getThumbnail());
                        mBitmap = BitmapFactory.decodeStream(url.openConnection().getInputStream());

                    } catch (MalformedURLException e) {

                    } catch (IOException e) {

                    }
                    return null;
                }
            }.execute();


            mViewHolder.thumbnail.setImageBitmap(mBitmap);
        }

        mViewHolder.author.setText(mPost.getAuthor());
        mViewHolder.title.setText(mPost.title);
        mViewHolder.date.setText(mPost.date);

        return convertView;
    }