Android之实现“抽奖大轮盘”

这个实例能够帮助我们学习旋转动画和计时器这两个知识点，废话不多说，上主程序：

package com.bear.lotterywheel;

import java.util.Timer;
import java.util.TimerTask;

import android.app.Activity;
import android.os.Bundle;
import android.os.Handler;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.animation.Animation.AnimationListener;
import android.view.animation.Animation;
import android.view.animation.RotateAnimation;
import android.widget.ImageView;
import android.widget.Toast;

public class MainActivity extends Activity {

	//设置一个时间常量，此常量有两个作用，1.圆灯视图显示与隐藏中间的切换时间；2.指针转一圈所须要的时间。现设置为500毫秒
	private static final long ONE_WHEEL_TIME = 500;
	//记录圆灯视图是否显示的布尔常量
	private boolean lightsOn = true;
	//開始转动时候的角度，初始值为0
	private int startDegree = 0;

	private ImageView lightIv;
	private ImageView pointIv;
	private ImageView wheelIv;

	//指针转圈圈数数据源
	private int[] laps = { 5, 7, 10, 15 };
	//指针所指向的角度数据源，由于有6个选项，全部此处是6个值
	private int[] angles = { 0, 60, 120, 180, 240, 300 };
	//转盘内容数组
	private String[] lotteryStr = { "索尼PSP", "10元红包", "谢谢參与", "DNF钱包",
			"OPPO MP3", "5元红包", };

	//子线程与UI线程通信的handler对象
	private Handler mHandler = new Handler() {

		public void handleMessage(android.os.Message msg) {
			switch (msg.what) {
			case 0:
				if (lightsOn) {
					// 设置lightIv不可见
					lightIv.setVisibility(View.INVISIBLE);
					lightsOn = false;
				} else {
					// 设置lightIv可见
					lightIv.setVisibility(View.VISIBLE);
					lightsOn = true;
				}
				break;

			default:
				break;
			}
		};

	};

	//监听动画状态的监听器
	private AnimationListener al = new AnimationListener() {

		@Override
		public void onAnimationStart(Animation animation) {
			// TODO Auto-generated method stub

		}

		@Override
		public void onAnimationRepeat(Animation animation) {
			// TODO Auto-generated method stub

		}

		@Override
		public void onAnimationEnd(Animation animation) {
			String name = lotteryStr[startDegree % 360 / 60];
			Toast.makeText(MainActivity.this, name, Toast.LENGTH_LONG).show();
		}
	};

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.activity_main);

		setupViews();
		flashLights();

		pointIv.setOnClickListener(new OnClickListener() {

			@Override
			public void onClick(View v) {
				int lap = laps[(int) (Math.random() * 4)];
				int angle = angles[(int) (Math.random() * 6)];
				//每次转圈角度增量
				int increaseDegree = lap * 360 + angle;
				//初始化旋转动画，后面的四个參数是用来设置以自己的中心点为圆心转圈
				RotateAnimation rotateAnimation = new RotateAnimation(
						startDegree, startDegree + increaseDegree,
						RotateAnimation.RELATIVE_TO_SELF, 0.5f,
						RotateAnimation.RELATIVE_TO_SELF, 0.5f);
				//将最后的角度赋值给startDegree作为下次转圈的初始角度
				startDegree += increaseDegree;
				//计算动画播放总时间
				long time = (lap + angle / 360) * ONE_WHEEL_TIME;
				//设置动画播放时间
				rotateAnimation.setDuration(time);
				//设置动画播放完后，停留在最后一帧画面上
				rotateAnimation.setFillAfter(true);
				//设置动画的加速行为，是先加速后减速
				rotateAnimation.setInterpolator(MainActivity.this,
						android.R.anim.accelerate_decelerate_interpolator);
				//设置动画的监听器
				rotateAnimation.setAnimationListener(al);
				//開始播放动画
				pointIv.startAnimation(rotateAnimation);
			}
		});

	}

	private void setupViews(){
		lightIv = (ImageView) findViewById(R.id.light);
		pointIv = (ImageView) findViewById(R.id.point);
		wheelIv = (ImageView) findViewById(R.id.main_wheel);
	}

	//控制灯圈动画的方法
	private void flashLights() {

		Timer timer = new Timer();
		TimerTask tt = new TimerTask() {

			@Override
			public void run() {
				// 向UI线程发送消息
				mHandler.sendEmptyMessage(0);

			}
		};

		// 每隔ONE_WHEEL_TIME毫秒执行tt对象的run方法
		timer.schedule(tt, 0, ONE_WHEEL_TIME);
	}

	@Override
	public boolean onCreateOptionsMenu(Menu menu) {
		// Inflate the menu; this adds items to the action bar if it is present.
		getMenuInflater().inflate(R.menu.main, menu);
		return true;
	}

}

效果图例如以下：

完整project代码下载链接：

android之幸运抽奖大轮盘