AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.dhw"
    android:versionCode="1"
    android:versionName="1.0" >
    
    <!-- インターネット接続に必須-->
    <uses-permission android:name="android.permission.INTERNET"/>

    <uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="17" />

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name="com.example.dhw.MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

</manifest>

MainActivity.java

package com.example.dhw;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

import android.app.Activity;
import android.os.AsyncTask;
import android.os.Bundle;
import android.util.Log;

public class MainActivity extends Activity {

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

		AsyncTask<Void, Integer, String> task = new AsyncTask<Void, Integer, String>() {

			@Override
			protected String doInBackground(Void... params) {
				StringBuilder bld = new StringBuilder();
				try {
					// URLのデータを読み込む
					URL url = new URL("http://www.yahoo.co.jp");
					URLConnection connection = (HttpURLConnection) url.openConnection();
					InputStream is = connection.getInputStream();

					// feed.jsonを読み込む処理に似てます。
					BufferedReader buff = new BufferedReader(new InputStreamReader(is));
					String line = null;
					while ((line = buff.readLine()) != null) {
						bld.append(line);
					}

				} catch (MalformedURLException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
				return bld.toString();
			}

			@Override
			protected void onPostExecute(String result) {
				super.onPostExecute(result);
				Log.i("json", result.toString());
			}
		};
		task.execute();
	}
}