Android 学习之 Handler 浅析

一个小demo：从网络上get信息，每隔2秒显示一次。

此demo主要用到了handler的用法和网络通信。网络通信的方式有很多种，在这里选择了okhttp。

以为okhttp3.0较之前改动较大，用okhttp3.9.0的库遇到很多错误（访问超时，无法访问等）所以先改用okhttp2.7.5的库

public class MainActivity extends Activity {

    private TextView mTextView;
    private ImageView imgShow;
    private final String path = "http://60.205.204.0/time.php";
    private static final String TAG = "HTest";
    private final String path1 = "http://img08.oneniceapp.com/upload/show/2017/11/27/9656e0d4c046e9eb0622be5a06e0f44e.jpg-show.n640.jpg";
    private OkHttpClient client;
    private String result;
    private Request request, request1;

    private static final int TEST = 1;
    private static final int FALL = 2;
    private static final int PICTURE = 3;


    private void init() {
        client = new OkHttpClient();
        mTextView = (TextView) findViewById(R.id.text);
        imgShow = (ImageView) findViewById(R.id.imgShow);
    }


    Handler handler = new Handler() {
        @Override
        public void handleMessage(Message msg) {
            switch (msg.what) {
                case TEST:
                    mTextView.setText(result);
                    Log.d(TAG, "test show");
                    break;

                case PICTURE:
                    byte[] Picture = (byte[]) msg.obj;
                    Bitmap bitmap = BitmapFactory.decodeByteArray(Picture, 0, Picture.length);
                    imgShow.setImageBitmap(bitmap);
                    break;

                case FALL:
                    Toast.makeText(MainActivity.this, "network failed", Toast.LENGTH_SHORT).show();
                    break;
            }
        }
    };


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        init();
        initSyncData();
        initPicData();
    }


    private void initSyncData() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    while (true) {
                        request = new Request.Builder().url(path).build();
                        Response response = client.newCall(request).execute();
                        result = response.body().string();

                        Message message = handler.obtainMessage();
                        message.what = TEST;
                        handler.sendMessage(message);
                        try {
                            Thread.sleep(2000);
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }


                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }

    private void initPicData() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                try {
                    request1 = new Request.Builder().url(path1).build();
                    Response response1 = client.newCall(request1).execute();
                    byte[] Picture_bt = response1.body().bytes();
                    //throw handler update UI
                    Message message = handler.obtainMessage();
                    message.obj = Picture_bt;
                    message.what = PICTURE;
                    handler.sendMessage(message);

                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        }).start();
    }
}

----------------------------------------------------------------------------------

使用库 

-------------------------------------------------------------------------------------------------------------

okhttp和okhttp3的区别

http://blog.csdn.net/u012532559/article/details/52852105