Android之實現“抽獎大輪盤”

這個實例可以幫助我們學習旋轉動畫和計時器這兩個知識點，廢話不多說，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 {
	
	//設置一個時間常量，此常量有兩個作用，1.圓燈視圖顯示與隱藏中間的切換時間；2.指針轉一圈所需要的時間，現設置為500毫秒
	private static final long ONE_WHEEL_TIME = 500;
	//記錄圓燈視圖是否顯示的布爾常量
	private boolean lightsOn = true;
	//開始轉動時候的角度，初始值為0
	private int startDegree = 0;

	private ImageView lightIv;
	private ImageView pointIv;
	private ImageView wheelIv;
	
	//指針轉圈圈數數據源
	private int[] laps = { 5, 7, 10, 15 };
	//指針所指向的角度數據源，因為有6個選項，所有此處是6個值
	private int[] angles = { 0, 60, 120, 180, 240, 300 };
	//轉盤內容數組
	private String[] lotteryStr = { "索尼PSP", "10元紅包", "謝謝參與", "DNF錢包",
			"OPPO MP3", "5元紅包", };
	
	//子線程與UI線程通信的handler對象
	private Handler mHandler = new Handler() {

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

			default:
				break;
			}
		};

	};
	
	//監聽動畫狀態的監聽器
	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)];
				//每次轉圈角度增量
				int increaseDegree = lap * 360 + angle;
				//初始化旋轉動畫，後面的四個參數是用來設置以自己的中心點為圓心轉圈
				RotateAnimation rotateAnimation = new RotateAnimation(
						startDegree, startDegree + increaseDegree,
						RotateAnimation.RELATIVE_TO_SELF, 0.5f,
						RotateAnimation.RELATIVE_TO_SELF, 0.5f);
				//將最後的角度賦值給startDegree作為下次轉圈的初始角度
				startDegree += increaseDegree;
				//計算動畫播放總時間
				long time = (lap + angle / 360) * ONE_WHEEL_TIME;
				//設置動畫播放時間
				rotateAnimation.setDuration(time);
				//設置動畫播放完後，停留在最後一幀畫面上
				rotateAnimation.setFillAfter(true);
				//設置動畫的加速行為，是先加速後減速
				rotateAnimation.setInterpolator(MainActivity.this,
						android.R.anim.accelerate_decelerate_interpolator);
				//設置動畫的監聽器
				rotateAnimation.setAnimationListener(al);
				//開始播放動畫
				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);	
	}
	
	//控制燈圈動畫的方法
	private void flashLights() {

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

			@Override
			public void run() {
				// 向UI線程發送消息
				mHandler.sendEmptyMessage(0);

			}
		};

		// 每隔ONE_WHEEL_TIME毫秒運行tt對象的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;
	}

}

完整工程代碼下載鏈接：

android之幸運抽獎大輪盤