Load file from url problem - connection refused

I have piece of code in my Activity ( I start this from emulator )

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    TextView txt=(TextView)this.findViewById(R.id.lbl);
    try {

            URL url = new URL("http://localhost/test.json");
            URLConnection urlconnection = url.openConnection();
            long l = urlconnection.getContentLength();

            BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));
            String line;
            StringBuffer buffer=new StringBuffer();
            while ((line = in.readLine()) != null)
            {
               buffer.append(line);
            }
            in.close();
            System.out.println("bufer="+buffer.toString());
            txt.setText(buffer.toString());


        } catch (Exception exc) {

           exc.printStackTrace();

        }  
}

and my Manifest looks like

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package开发者_如何学编程="test_android.test"
      android:versionCode="1"
      android:versionName="1.0">


    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".test_android"
                  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>
     <uses-permission android:name="android.permission.INTERNET"></uses-permission>
</manifest>

I have wamp server and test.json in my www directory but I always get error CONNECTION REFUSED. What is wrong ?

in your URL, replace "localhost" with 10.0.2.2

that IP is a special emulator mapping to localhost

EDIT: for more information, see: http://developer.android.com/guide/developing/devices/emulator.html#emulatornetworking