Android—幸运抽奖&&火箭发射倒计时（第六次作业）

Android—幸运抽奖&&点火发射（第六次作业）

创建项目

准备工作

修改按钮的颜色，如果不修改这行代码，那么后期给按钮添加background属性的时候，按钮并不会发生变化。

设置按钮的样式文件btn_press_blue.xml，设置了按压效果

<?xml version="1.0" encoding="utf-8"?>
<selector xmlns:android="http://schemas.android.com/apk/res/android">
    <item android:state_pressed="true">     <!--按压-->
        <shape>
            <solid android:color="#0082FF"/>
            <corners android:radius="10dp"/>
        </shape>
    </item>

    <item android:state_pressed="false">
        <shape>
            <solid android:color="@color/blue"/>
            <corners android:radius="10dp"/>
        </shape>
    </item>
</selector>

其中蓝色的我选择的RGB是#FF7BBAF7

<color name="blue">#FF7BBAF7</color>

幸运抽奖

幸运⼤抽奖。⽤户单击“开始抽奖”Button后启动线程，开始抽奖过程，在界⾯上随机出现抽奖名单。用户点击”揭晓大奖“Button后，终止线程运行。

左侧为项目结构，红色方框为新增内容或者修改的内容，右侧简单展示上述准备工作中的局部代码。

布局文件activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal">

        <Button
            android:id="@+id/btn_start"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="开始抽奖了"
            android:textSize="20sp"
            android:background="@drawable/btn_press_blue"
            android:layout_margin="5dp"/>

        <Button
            android:id="@+id/btn_stop"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:text="揭晓大奖"
            android:textSize="20sp"
            android:background="@drawable/btn_press_blue"
            android:layout_margin="5dp"/>
    </LinearLayout>

    <TextView
        android:id="@+id/label"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="100dp"
        android:textSize="40sp"
        android:gravity="center"
        android:layout_gravity="center_horizontal"
        android:textColor="@color/blue"/>

    <TextView
        android:id="@+id/information"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="150dp"
        android:textSize="20sp"
        android:gravity="center"
        android:layout_gravity="center_horizontal"
        android:textColor="@color/blue"
        android:text="WeiComp 计科20xx 20200707xxxx 制作"/>

</LinearLayout>

1. 创建RandomService的java文件

   package com.example.servicedemo;
   
   public class RandomService extends Service {
         
         	//导包的时候导入android.app.Service
   
       private Thread luckThread;
   
       @Override
       public void onCreate() {
         
         
           super.onCreate();
           Toast.makeText(this, "幸运大抽奖开始", Toast.LENGTH_SHORT).show();
           luckThread = new Thread(null, backgroundWork, "luckThread");
       }
   
       @Override
       public void onStart(Intent intent, int startId) {
         
         
           super.onStart(intent, startId);
           Toast.makeText(this, "抽奖进行中", Toast.LENGTH_SHORT).show();
           if (!luckThread.isAlive()) {
         
         
               luckThread.start();
           }
       }
   
       @Override
       public void onDestroy() {
         
         
           super.onDestroy();
           Toast.makeText(this, "恭喜你中奖了", Toast.LENGTH_SHORT).show();
           luckThread.interrupt();
       }
   
       @Nullable
       @Override
       public IBinder onBind(Intent intent) {
         
         
           return null;
       }
   
       private Runnable backgroundWork = new Runnable() {
         
         
           @Override
           public void run() {
         
         
               try {
         
         
                   while (!Thread.interrupted()) {
         
         
                       int randomDouble = (int) Math.round(Math.random() * 2 + 1);
                       int randomDouble1 = (int) Math.round(Math.random() * 2);
                       int randomDouble2 = (int) Math.round(Math.random() * 9);
                       MainActivity.UpdateGUI(randomDouble, randomDouble1, randomDouble2);
                       Thread.sleep(1000);
                       if (randomDouble1 == randomDouble2 && randomDouble1 == 0) {
         
         
                           luckThread.interrupt();
                       }
                   }
               } catch (InterruptedException e) {
         
         
                   e.printStackTrace();
               }
           }
       };
   }
   

2. MainAcitivty.java函数

   package com.example.servicedemo;
   
   public class MainActivity extends AppCompatActivity {
         
         
   
       private Button btn_start, btn_stop;
       private static Handler handler = new Handler();
       private static TextView labelView = null;
       private static int randomDouble, randomDouble1, randomDouble2;
   
   
       @Override
       protected void onCreate(Bundle savedInstanceState) {
         
         
           super.onCreate(savedInstanceState);
           setContentView(R.layout.activity_main);
   
           btn_start = findViewById(R.id.btn_start);
           btn_stop = findViewById(R.id.btn_stop);
           labelView = findViewById(R.id.label);
   
           handler = new Handler();
   
           final Intent serviceIntent = new Intent(this, RandomService.class);
           btn_start.setOnClickListener(new View.OnClickListener() {
         
         
               @Override
               public void onClick(View view) {
         
         
                   startService(serviceIntent);
               }
           });
   
           btn_stop.setOnClickListener(new View.OnClickListener() {
         
         
               @Override
               public void onClick(View view) {
         
         
                   stopService(serviceIntent);
                   handler.post(RefreshLable);
               }
           });
       }
   
       @Override
       public void onDestroy() {
         
         
           super.onDestroy();
           MainActivity.UpdateGUI(randomDouble, randomDouble1, randomDouble2);
           Toast.makeText(this, "恭喜你中奖了", Toast.LENGTH_SHORT).show();
       }
   
   
       public static void UpdateGUI(int refreshDouble, int refreshDouble1, int refreshDouble2) {
         
         
           randomDouble = refreshDouble;
           randomDouble1 = refreshDouble1;
           randomDouble2 = refreshDouble2;
           handler.post(RefreshLable);
       }
   
       private static Runnable RefreshLable = new Runnable() {
         
         
           @Override
           public void run() {
         
         
               labelView.setText(String.valueOf("20200707" + randomDouble +
                       randomDouble1 +
                       randomDouble2));
           }
       };
   }
   

3. 修改AndroidManifest.xml代码(确保将服务的启动和停止操作正确注册在 AndroidManifest.xml 中。)

   <application>
       ...
       <service
           android:name=".RandomService"
           android:enabled="true"
           android:exported="false" />
       ...
   </application>
   

   

效果图

火箭发射倒计时

使用Timer实现火箭倒计时功能。（参照例6-6）请在界面适当的位置添加个人信息，如姓名或拼音，以防止作业雷同。上传代码及模拟器图片。

【例6-6】火箭点火倒计时。在UI界面上设计一个TextView和一个Button。当用户点击Button时，启动Timer工作，在TextView上显示10至1的倒计时数字，数字每秒变化一次。当显示到1后，TextView上显示“点火成功”。

布局文件activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="10dp">

    <TextView
        android:id="@+id/textview"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="100dp"
        android:textSize="40sp"
        android:textColor="@color/blue"
        android:gravity="center" />

    <Button
        android:id="@+id/button"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@drawable/btn_press_blue"
        android:text="点火发射"
        android:textSize="25sp"
        android:textColor="@color/white"
        android:layout_centerInParent="true" />
	<TextView
        android:id="@+id/information"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="500dp"
        android:textSize="20sp"
        android:gravity="center"
        android:layout_gravity="center_horizontal"
        android:textColor="@color/blue"
        android:text="WeiComp 计科20xx 20200707xxxx 制作"/>

</RelativeLayout>

MainActivity.java

package com.example.timerdemo;

public class MainActivity extends AppCompatActivity {
    
    

    private Button button;
    private TextView textView;
    private Timer timer;
    private TimerTask timerTask;

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

        textView = findViewById(R.id.textview);
        button = findViewById(R.id.button);

        button.setOnClickListener(new View.OnClickListener() {
    
    
            @Override
            public void onClick(View v) {
    
    
                startTimer();
            }
        });
    }

    private void startTimer() {
    
    
        timer = new Timer();

        timerTask = new TimerTask() {
    
    
            int i = 10; //倒计时数目

            @Override
            public void run() {
    
    
                Message message = Message.obtain();
                message.what = i;
                handler.sendMessage(message);
                i--;
            }
        };

        timer.schedule(timerTask, 1000, 1000);
    }

    @SuppressLint("HandlerLeak")
    private Handler handler = new Handler() {
    
    
        @Override
        public void handleMessage(@NonNull Message msg) {
    
    
            super.handleMessage(msg);
            if (msg.what > 0) {
    
    
                textView.setText(" " + msg.what);
            } else {
    
    
                // 在handler里可以更改UI组件
                textView.setText("点火成功");
                timer.cancel();
            }
        }
    };
}

运行结果