Android中如何使用基于回调的事件处理

编写接口

public interface DownloadCallback {    void startDownload();    void updateProgress(int progress);    void finishedDownload();}

编写事件源

public class HttpUtil {    private Timer mTimer;    private TimerTask mTimerTask;    private DownloadCallback mCallback;    public void setCallback(DownloadCallback callback) {        this.mCallback = callback;    }    public HttpUtil() {        mTimer = new Timer();        mTimerTask = new TimerTask() {            int i = 0;            @Override            public void run() {                if (i < 100) {                    mCallback.updateProgress(i++);                } else {                    mCallback.finishedDownload();                    mTimer.cancel();                } } };    }    public void donwload() {        mCallback.startDownload();        mTimer.schedule(mTimerTask, 1000, 50);    }}

设置事件

public class DownloadActivity extends Activity implements DownloadCallback {    private HttpUtil mHttpUtil;    private final String TAG = DownloadActivity.class.getSimpleName();    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_download);  mHttpUtil = new HttpUtil();        mHttpUtil.setCallback(this);    }    @Override    public void startDownload() {        Log.i(TAG, "开始下载");    }    @Override    public void updateProgress(int progress) {        Log.i(TAG, "已下载" + progress + "%");    }    @Override    public void finishedDownload() {        Log.i(TAG, "下载完成");    }}

触发事件

   @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_download);        downloadBtn = findViewById(R.id.btn_download);        mHttpUtil = new HttpUtil();        mHttpUtil.setCallback(this);        downloadBtn.setOnClickListener(new View.OnClickListener() {            @Override            public void onClick(View v) {                mHttpUtil.donwload();            }        });    }

查看效果

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