android使用httclient获取服务器端数据失败，但是用java工程运行就可以成功获取。报错

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各位 刚接触android，请教个问题，android使用httpclient获取服务器端的json数据总是失败，但是同样的代码用java工程来运行就可以获取结果，这个是为什么？

代码很简短： 但是总是连接失败

protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    String content = "";
    TextView tv = (TextView) findViewById(R.id.showWiki);
    String url = "http://www.nowamagic.net/academy/android/";
    HttpClient httpclient = new DefaultHttpClient();
    HttpGet httpget = new HttpGet(url);
    ResponseHandler<String> responseHandler = new BasicResponseHandler();
    try {
        content = httpclient.execute(httpget, responseHandler);
        Toast.makeText(getApplicationContext(), "连接成功！", Toast.LENGTH_SHORT).show();
        tv.setText(content);
    } catch (Exception e) {
        // TODO: handle exception
        Toast.makeText(getApplicationContext(), "连接失败！", Toast.LENGTH_SHORT).show();
        e.printStackTrace();
    }
    httpclient.getConnectionManager().shutdown();
}

<uses-permission android:name="android.permission.INTERNET"></uses-permission> 这句话我也加了