Android实现心跳的效果

最近再做一个教育类的项目。在做一些学习工具的时候，美工提出了一些要求，大致如下：

其实实现过程也不难，大致就是对一个视图控件添加一个圆形的背景，然后该视图进行动画处理，膨胀的同时，透明度增大，收缩的同时，透明度降低。

我在例子中是使用了TextView，所以首先对TextView添加一个圆形的背景：

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval" >

    <size
        android:height="90dp"
        android:width="90dp" />

    <solid android:color="@color/color_space_studytools_red" />

    <corners android:radius="180dip" />

    <padding
        android:bottom="4dip"
        android:left="4dip"
        android:right="4dip"
        android:top="4dip" />

</shape>

然后为TextView添加动画，包括调整大小的ScaleAnimation和调整透明度的AlphaAnimation。调整大小有两个部分，膨胀和收缩。在膨胀完毕后马上收缩，也就是对膨胀的动画进行监听，在onAnimationEnd()方法里面进行收缩，

	// 按钮模拟心脏跳动
	private void playHeartbeatAnimation(final View heartbeatView) {
		AnimationSet swellAnimationSet = new AnimationSet(true);
		swellAnimationSet.addAnimation(new ScaleAnimation(1.0f, 1.8f, 1.0f, 1.8f, Animation.RELATIVE_TO_SELF, 0.5f,
				Animation.RELATIVE_TO_SELF, 0.5f));
		swellAnimationSet.addAnimation(new AlphaAnimation(1.0f, 0.3f));

		swellAnimationSet.setDuration(500);
		swellAnimationSet.setInterpolator(new AccelerateInterpolator());
		swellAnimationSet.setFillAfter(true);

		swellAnimationSet.setAnimationListener(new AnimationListener() {

			@Override
			public void onAnimationStart(Animation animation) {
			}

			@Override
			public void onAnimationRepeat(Animation animation) {
			}

			@Override
			public void onAnimationEnd(Animation animation) {
				AnimationSet shrinkAnimationSet = new AnimationSet(true);
				shrinkAnimationSet.addAnimation(new ScaleAnimation(1.8f, 1.0f, 1.8f, 1.0f, Animation.RELATIVE_TO_SELF,
						0.5f, Animation.RELATIVE_TO_SELF, 0.5f));
				shrinkAnimationSet.addAnimation(new AlphaAnimation(0.3f, 1.0f));
				shrinkAnimationSet.setDuration(1000);
				shrinkAnimationSet.setInterpolator(new DecelerateInterpolator());
				shrinkAnimationSet.setFillAfter(false);
				heartbeatView.startAnimation(shrinkAnimationSet);// 动画结束时重新开始，实现心跳的View
			}
		});

		heartbeatView.startAnimation(swellAnimationSet);
	}

心跳的效果是要不停地膨胀和收缩，所以要开一个线程来处理，每当收缩完毕后重新膨胀。

private class HeatbeatThread extends Thread {
		public void run() {
			try {
				sleep(100);
			} catch (InterruptedException e1) {
				e1.printStackTrace();
			}
			while (true) {
				runOnUiThread(new Runnable() {
					public void run() {
						for (View view : heartbeatViews) {
							playHeartbeatAnimation(view);
						}
					}
				});
				try {
					Thread.sleep(1500);
				} catch (InterruptedException e) {
					e.printStackTrace();
				}
			}
		};
	}

最后和Activity的生命周期结合，对线程进行开始和结束。

	private Thread heartbeatThread;

	/**
	 * 开始心跳
	 */
	private void startHeartBeat() {
		if (heartbeatThread == null) {
			heartbeatThread = new HeatbeatThread();
		}
		if (!heartbeatThread.isAlive()) {
			heartbeatThread.start();
		}
	}

	/**
	 * 停止心跳
	 */
	private void stopHeartBeat() {
		if (heartbeatThread != null && heartbeatThread.isInterrupted()) {
			heartbeatThread.interrupt();
			heartbeatThread = null;
			System.gc();
		}
	}

	@Override
	protected void onResume() {
		super.onResume();
		startHeartBeat();
	}

	@Override
	protected void onPause() {
		super.onPause();
		stopHeartBeat();
	}

Demo下载为：http://download.csdn.net/detail/u014375869/8838599