用volley訪问server数据，不用自己额外开线程。以下样例为訪问JSONObject类型的数据，详细使用方法看代码：
首先得有volley的jar包，假设自己没有。去github上下载，然后自己打成jar包，假设不会，能够用我的。附上jar包链接：http://download.csdn.net/detail/u010127250/8769021

RequestQueue mQueue;
@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.login);
		context = this;
		mQueue = Volley.newRequestQueue(context);
}
//LOGIN_PATH：String类型。訪问server的地址 如：http://192.168.1.2:8080/mytest/LoginServlet (ip为serverip地址，mytest为project名)
//dataObject：JSONObject类型，訪问server时。给server传的參数，能够为null。
JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(LOGIN_PATH,
				dataObject, new Response.Listener<JSONObject>() {
					@Override
					public void onResponse(JSONObject response) {
						
						Log.e("TAG", response.toString());
						String result = Tools.jsonToString(response);
						if (result.equals("login_success")) {
							handler.sendMessage(handler.obtainMessage(2));
						}
						if (result.equals("password_wrong")) {
							handler.sendMessage(handler.obtainMessage(1));
						}
						if (result.equals("usrename_null")) {
							handler.sendMessage(handler.obtainMessage(0));
						} 
					}
				}, new Response.ErrorListener() {
					@Override
					public void one rrorResponse(VolleyError error) {
						Log.e("TAG", error.getMessage(), error);
						handler.sendMessage(handler.obtainMessage(-2));
					}
				});
		mQueue.add(jsonObjectRequest);