Android中回调下载事件处理实现步骤

1. 编写接口

public interface DownloadCallback {

    void startDownload();

    void updateProgress(int progress);

    void finishedDownload();
}

2. 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);
       }}
   

3. 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");
   	    }
   	}
   	```
   

4. 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();
               }
           });
       }
   

5. 查看效果