本文实例为大家分享了Chronometer实现倒计时功能，Android提供了实现按照秒计时的API，供大家参考，具体内容如下
一、自定义ChronometerView 继续自TextView
主要原理：先设置一个基准倒计时时间mBaseSeconds，内置handler 每隔1s发送一个空消息，mRemainSeconds--，同时刷新界面视图，回调给外部调用者，只到为零。外部调用者可通过start()/pause()/stop()来控制计时器的工作状态。
可以app中发送短信验证码的场景为例，做了一个很粗糙的界面，但功能都实现了。
/** * @name 倒计时器（类似妙表倒数计时，支持暂停、停止、重新开始） * @author Fanjb * @date 2015年11月6日 */ public class ChronometerView extends TextView { /** * A callback that notifies when the chronometer has decremented on its own. * * @author Fanjb */ public interface OnTickChangeListener { /** * remain seconds changed * * @param view * @param remainSeconds */ public void onTickChanged(ChronometerView view, long remainSeconds); } private long mBase; private long mRemainSeconds; private boolean mStarted; private boolean mReStart; private boolean mVisible; private boolean mIsEnable; private OnTickChangeListener mTickListener; public ChronometerView(Context context) { this(context, null); } public ChronometerView(Context context, AttributeSet attrs) { super(context, attrs, 0); } public ChronometerView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); updateText(mRemainSeconds); } @Override protected void onWindowVisibilityChanged(int visibility) { super.onWindowVisibilityChanged(visibility); mVisible = visibility == VISIBLE; updateStatus(); } @Override protected void onDetachedFromWindow() { super.onDetachedFromWindow(); mVisible = false; updateStatus(); } /** * 启动计时器 */ public void start() { if (mReStart && !mStarted) { mRemainSeconds = mBase; } mStarted = true; updateStatus(); } /** * 暂停计时器 */ public void pause() { if (mStarted) { mStarted = mReStart = false; updateStatus(); } } /** * 停止计时器，再次调用 start()重新启动 */ public void stop() { mStarted = false; mReStart = true; updateStatus(); updateText(mRemainSeconds = 0); dispatchTickListener(); } /** * 刷新内部状态 */ private void updateStatus() { boolean isEnable = mVisible && mStarted; if (mIsEnable != isEnable) { if (isEnable) { mHandler.sendMessage(Message.obtain(mHandler, TICK_WHAT)); } else { mHandler.removeMessages(TICK_WHAT); } mIsEnable = isEnable; } } private static final int TICK_WHAT = 1; private Handler mHandler = new Handler() { public void handleMessage(android.os.Message msg) { if (mRemainSeconds > 0) { updateText(--mRemainSeconds); dispatchTickListener(); sendMessageDelayed(Message.obtain(this, TICK_WHAT), 1000); } } }; private void updateText(long now) { String text = DateUtils.formatElapsedTime(now); setText(text); } /** * 在未启动状态下设置开始倒计时时间 * * @param baseSeconds */ public void setBaseSeconds(long baseSeconds) { if (baseSeconds > 0 && baseSeconds != mBase && !mStarted) { mBase = mRemainSeconds = baseSeconds; updateText(mRemainSeconds); } } /** * 剩余时间 * * @return */ public long getRemainSeconds() { return mRemainSeconds; } public void setOnTickChangeListener(OnTickChangeListener listener) { mTickListener = listener; } public OnTickChangeListener getTickListener() { return mTickListener; } private void dispatchTickListener() { if (mTickListener != null) { mTickListener.onTickChanged(this, getRemainSeconds()); } } @Override public void onInitializeAccessibilityEvent(AccessibilityEvent event) { super.onInitializeAccessibilityEvent(event); event.setClassName(ChronometerView.class.getName()); } @Override public void onInitializeAccessibilityNodeInfo(AccessibilityNodeInfo info) { super.onInitializeAccessibilityNodeInfo(info); info.setClassName(Chronometer.class.getName()); } }
二、xml 中没有加入自定义的控件属性，同TextView
<LinearLayout android:layout_width="wrap_content" android:layout_height="wrap_content" android:orientation="horizontal" > <com.freedoman.widgets.calendar.ChronometerView android:id="@+id/chronometer_view" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="5dp" android:background="@drawable/chronometer_view_bg" android:enabled="true" android:text="00:00" /> <Button android:id="@+id/start_chronometer_view_btn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="5dp" android:text="Start" /> <Button android:id="@+id/pause_chronometer_view_btn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="5dp" android:text="Pause" /> <Button android:id="@+id/stop_chronometer_view_btn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginLeft="5dp" android:text="Stop" /> </LinearLayout>
三、在Activity中做一个简单的测试（可以发送短信验证码的实际应用场景为例）
public class ChronometerActivity extends Activity { private ChronometerView mChronometerView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_clock); // 自定义计时器 if (mChronometerView == null) { mChronometerView = (ChronometerView) findViewById(R.id.chronometer_view); mChronometerView.setBaseSeconds(60); mChronometerView.setOnTickChangeListener(new OnTickChangeListener() { @Override public void onTickChanged(ChronometerView view, long curTimeMills) { System.out.println(curTimeMills); view.setEnabled(curTimeMills == 0 || curTimeMills == 60); if (curTimeMills == 0) { mChronometerView.setText("重新发送"); } } }); mChronometerView.setText("点击发送验证码"); } findViewById(R.id.start_chronometer_view_btn).setOnClickListener(mClickListener); findViewById(R.id.pause_chronometer_view_btn).setOnClickListener(mClickListener); findViewById(R.id.stop_chronometer_view_btn).setOnClickListener(mClickListener); } private View.OnClickListener mClickListener = new OnClickListener() { @Override public void onClick(View v) { switch (v.getId()) { case R.id.start_chronometer_view_btn: if (mChronometerView != null) { mChronometerView.start(); } break; case R.id.pause_chronometer_view_btn: if (mChronometerView != null) { mChronometerView.pause(); } break; case R.id.stop_chronometer_view_btn: if (mChronometerView != null) { mChronometerView.stop(); } break; } } }; }
以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持查字典教程网。
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