这是一个简单的定时器，分别为3S，5S和10S。倒计时的过程中，界面上会显示数字，数字的显示用了一些渐变动画，效果看起来还不错。
这个程序是自己写的，所以只是在UI线程中做的，实际项目上使用肯定需要不断完善。
xml代码如下：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context=".MainActivity" android:background="@android:color/background_dark" > <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal"> <Button android:id="@+id/timer_three_second" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="3S倒计时"/> <Button android:id="@+id/timer_five_second" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="5S倒计时"/> <Button android:id="@+id/timer_ten_second" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_weight="1" android:text="10S倒计时"/> </LinearLayout> <LinearLayout android:id="@+id/timer_root_view" android:layout_width="match_parent" android:layout_height="wrap_content" android:gravity="center_horizontal" android:layout_marginTop="100dp" > </LinearLayout></LinearLayout>
Java代码如下：
package com.jackie.timer;import android.os.Handler;import android.os.Message;import android.support.v7.app.ActionBarActivity;import android.os.Bundle;import android.util.Log;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.animation.AlphaAnimation;import android.view.animation.Animation;import android.view.animation.AnimationSet;import android.view.animation.ScaleAnimation;import android.widget.Button;import android.widget.ImageView;import android.widget.LinearLayout;import android.widget.Toast;public class MainActivity extends ActionBarActivity implements View.OnClickListener { private LinearLayout mTimerRootView; private Button mThreeBtn; private Button mFiveBtn; private Button mTenBtn; private ImageView mTimerView; private AnimationSet mAnimationSet; //用来记录倒计时的时间 private int mCurrentValue = 0; private final int SECOND_1 = 1000; /** * @fields TIMER_ICON_IDS : TODO 倒计时事件图片 */ public static final int[] TIMER_ICON_IDS = new int[]{ 0, //从1开始，没有0 R.drawable.camera_timer_icon_1, R.drawable.camera_timer_icon_2, R.drawable.camera_timer_icon_3, R.drawable.camera_timer_icon_4, R.drawable.camera_timer_icon_5, R.drawable.camera_timer_icon_6, R.drawable.camera_timer_icon_7, R.drawable.camera_timer_icon_8, R.drawable.camera_timer_icon_9, R.drawable.camera_timer_icon_10, }; private static final int MSG_UPDATE_TIMER_VALUE = 0; private Handler mHandler = new Handler() { @Override public void handleMessage(Message msg) { switch (msg.what) { case MSG_UPDATE_TIMER_VALUE: remindTimeValue(); break; } } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); mTimerRootView = (LinearLayout) findViewById(R.id.timer_root_view); mThreeBtn = (Button) findViewById(R.id.timer_three_second); mFiveBtn = (Button) findViewById(R.id.timer_five_second); mTenBtn = (Button) findViewById(R.id.timer_ten_second); mThreeBtn.setOnClickListener(this); mFiveBtn.setOnClickListener(this); mTenBtn.setOnClickListener(this); } @Override public boolean onCreateOptionsMenu(Menu menu) { // Inflate the menu; this adds items to the action bar if it is present. getMenuInflater().inflate(R.menu.menu_main, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { // Handle action bar item clicks here. The action bar will // automatically handle clicks on the Home/Up button, so long // as you specify a parent activity in AndroidManifest.xml. int id = item.getItemId(); //noinspection SimplifiableIfStatement if (id == R.id.action_settings) { return true; } return super.onOptionsItemSelected(item); } @Override public void onClick(View v) { switch (v.getId()) { case R.id.timer_three_second: mCurrentValue = 3; break; case R.id.timer_five_second: mCurrentValue = 5; break; case R.id.timer_ten_second: mCurrentValue = 10; break; } mHandler.sendEmptyMessage(MSG_UPDATE_TIMER_VALUE); } private void remindTimeValue() { if (mCurrentValue <= 0) { Toast.makeText(this, "倒计时结束", Toast.LENGTH_LONG).show(); } else { //更新界面 showTimerRemind(); mCurrentValue--; //每个1S再发送消息 mHandler.sendEmptyMessageDelayed(MSG_UPDATE_TIMER_VALUE, SECOND_1); } } private void showTimerRemind() { runOnUiThread(new Runnable() { @Override public void run() { //创建倒计时显示的View creatTimerView(); //创建动画 initAnimation(); if(mCurrentValue > 0 && mCurrentValue < TIMER_ICON_IDS.length){ //【功能说明】该方法用于设置一个动画效果执行完毕后，View对象保留在终止的位置。 // 该方法的执行，需要首先通过setFillEnabled方法使能填充效果，否则设置无效。 mAnimationSet.setFillAfter(true); mTimerView.setImageDrawable(getDrawable(TIMER_ICON_IDS[mCurrentValue])); mTimerView.setVisibility(View.VISIBLE); mTimerView.startAnimation(mAnimationSet); } } }); } private void creatTimerView() { if(mTimerView == null) { mTimerView = new ImageView(MainActivity.this); mTimerRootView.addView(mTimerView); } } private void initAnimation() { ScaleAnimation mScale = new ScaleAnimation(1.0f, 0.5f, //X from 1 to 0.5 1.0f, 0.5f, //Y from 1 to 0.5 Animation.RELATIVE_TO_SELF, 0.5f, Animation.RELATIVE_TO_SELF, 0.5f); AlphaAnimation mAlpha = new AlphaAnimation(0f, 1f); mAnimationSet = new AnimationSet(true); mAnimationSet.addAnimation(mScale); mAnimationSet.addAnimation(mAlpha); mAnimationSet.setDuration(600); mAnimationSet.setAnimationListener(new Animation.AnimationListener() { @Override public void onAnimationStart(Animation animation) { if(mTimerView != null){ mTimerView.setVisibility(View.INVISIBLE); mAnimationSet.setFillAfter(false); } } @Override public void onAnimationEnd(Animation animation) { } @Override public void onAnimationRepeat(Animation animation) { } }); mAnimationSet.setFillAfter(true); }}效果如下：
由于数字的变化有个渐变的过程，所以不太好截图，具体效果大家可以看真机。
其次这个程序没有考虑到一些case，比如，在倒计时的过程中，就不允许再点击按钮等等。