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: }