Android开发——HTTP通讯

说Android是一款互联网手机操作系统一点也不过为过。打开G2的"大抽屉”，一大堆的软件，大部分都是需要网络支持才能正常运行的。

曾经和同学说：没有网络支持，G2跟Nokia 1200没啥区别！

既然Android定位为“网络操作系统”，自然提供了很威水的网络访问接口。既有java.net.*,又有org.apache.http.*，在数据处理方面支持json，xml等常用的数据格式。

示例代码如下：

   1:  

   2: public class HttpDemo extends Activity {

   3:  

   4:     private static final int MSGWHAT = 0x000000;

   5:  

   6:     private TextView textView;

   7:     private Button btnLink;

   8:     private EditText etUrl;

   9:     private String data;

  10:     /**

  11:      * 消息控制器，用来更新界面，因为在普通线程是无法用来更新界面的

  12:      */

  13:     private Handler handler = new Handler() {

  14:         @Override

  15:         public void handleMessage(Message msg) {

  16:             switch (msg.what) {

  17:             case MSGWHAT:

  18:                 //设置显示文本

  19:                 textView.setText(data);

  20:                 break;

  21:             default:

  22:                 break;

  23:             }

  24:         }

  25:     };

  26:  

  27:     /** Called when the activity is first created. */

  28:     @Override

  29:     public void onCreate(Bundle savedInstanceState) {

  30:         super.onCreate(savedInstanceState);

  31:         setContentView(R.layout.main);

  32:         //注意界面控件的初始化的位置,不要放在setContentView()前面

  33:         initComponent();

  34:         btnLink.setOnClickListener(new OnClickListener() {

  35:  

  36:             @Override

  37:             public void onClick(View v) {

  38:                 //可以放在另外的线程完成

  39:                 try {

  40:                     data = getData();

  41:                 } catch (ClientProtocolException e) {

  42:                     data = e.getMessage();

  43:                 } catch (IOException e) {

  44:                     data = e.getMessage();

  45:                 } catch (URISyntaxException e) {

  46:                     data = e.getMessage();

  47:                 }

  48:                 Message msg = new Message();

  49:                 msg.what = MSGWHAT;

  50:                 handler.sendMessage(msg);

  51:             }

  52:         });

  53:     }

  54:  

  55:     /**

  56:      * 初始化界面组件

  57:      */

  58:     private void initComponent() {

  59:         textView = (TextView) findViewById(R.id.text);

  60:         btnLink = (Button) findViewById(R.id.btn_link);

  61:         etUrl = (EditText) findViewById(R.id.url);

  62:     }

  63:  

  64:     /**

  65:      * 取数据

  66:      * @return

  67:      * @throws ClientProtocolException

  68:      * @throws IOException

  69:      * @throws URISyntaxException

  70:      */

  71:     private String getData() throws ClientProtocolException, IOException, URISyntaxException {

  72:         String urlString = etUrl.getText().toString();

  73:         return request(urlString);

  74:     }

  75:  

  76:     /**

  77:      * 发送请求

  78:      * @param url 请求地址

  79:      * @return

  80:      * @throws ClientProtocolException

  81:      * @throws IOException

  82:      * @throws URISyntaxException

  83:      */

  84:     private String request(String url) throws ClientProtocolException, IOException, URISyntaxException {

  85:         HttpClient httpClient = new DefaultHttpClient();

  86:         URI uri = URIUtils.createURI("http", url, -1, null, null, null);

  87:         HttpGet get = new HttpGet(uri);

  88:         ResponseHandler<String> responseHandler = new BasicResponseHandler();

  89:         return httpClient.execute(get, responseHandler);

  90:     }

  91:     

  92:     @Override

  93:     protected void onDestroy() {

  94:         super.onDestroy();

  95:         System.gc();

  96:         System.exit(0);

  97:     }

  98: }