Android学习指南之二十五：Android动画的实现 下

本节讲解使用SurfaceView组件绘制动画的方法。SurfaceView类作为View类的子类，进行绘图时能够比一般的View组件更快，所以我们在Android游戏、视频等对流畅度和帧速要求较高的应用中经常会见到SurfaceView的身影。

本文通过实例讲解的方式来介绍SurfaceView的使用方法，此实例实现的是一个能发送莫尔斯码的灯塔。下面是详细步骤，代码中的注释可以帮助大家理解。

1、创建项目Lesson25_Morse，启动Activity名字叫MainActivity.java。

2、创建一个莫尔斯码的工具类Morse.java。

package basic.android.lesson37;   
      
    import java.util.HashMap;   
    import java.util.Map;   
      
    public class Morse {   
      
        public static Map<STRING string ,> standardMorseCharactersMap = new HashMap</STRING><STRING string ,>();   
      
        static {   
            standardMorseCharactersMap.put("a", ".-");   
            standardMorseCharactersMap.put("b", "-...");   
            standardMorseCharactersMap.put("c", "-.-.");   
            standardMorseCharactersMap.put("d", "-..");   
            standardMorseCharactersMap.put("e", ".");   
            standardMorseCharactersMap.put("f", "..-.");   
            standardMorseCharactersMap.put("g", "--.");   
            standardMorseCharactersMap.put("h", "....");   
            standardMorseCharactersMap.put("i", "..");   
            standardMorseCharactersMap.put("j", ".---");   
            standardMorseCharactersMap.put("k", "-.-");   
            standardMorseCharactersMap.put("l", ".-..");   
            standardMorseCharactersMap.put("m", "--");   
            standardMorseCharactersMap.put("n", "-.");   
            standardMorseCharactersMap.put("o", "---");   
            standardMorseCharactersMap.put("p", ".--.");   
            standardMorseCharactersMap.put("q", "--.-");   
            standardMorseCharactersMap.put("r", ".-.");   
            standardMorseCharactersMap.put("s", "...");   
            standardMorseCharactersMap.put("t", "-");   
            standardMorseCharactersMap.put("u", "..-");   
            standardMorseCharactersMap.put("v", "...-");   
            standardMorseCharactersMap.put("w", ".--");   
            standardMorseCharactersMap.put("x", "-..-");   
            standardMorseCharactersMap.put("y", "-.--");   
            standardMorseCharactersMap.put("z", "--..");   
      
            standardMorseCharactersMap.put("0", "-----");   
            standardMorseCharactersMap.put("1", ".----");   
            standardMorseCharactersMap.put("2", "..---");   
            standardMorseCharactersMap.put("3", "...--");   
            standardMorseCharactersMap.put("4", "....-");   
            standardMorseCharactersMap.put("5", ".....");   
            standardMorseCharactersMap.put("6", "-....");   
            standardMorseCharactersMap.put("7", "--...");   
            standardMorseCharactersMap.put("8", "---..");   
            standardMorseCharactersMap.put("9", "----.");   
      
            standardMorseCharactersMap.put(".", ".-.-.-");   
            standardMorseCharactersMap.put("-", "-....-");   
            standardMorseCharactersMap.put(",", "--..--");   
            standardMorseCharactersMap.put("?", "..--..");   
            standardMorseCharactersMap.put("/", "-..-.");   
            standardMorseCharactersMap.put(";", "-.-.-.");   
            standardMorseCharactersMap.put("(", "-.--.");   
            standardMorseCharactersMap.put(")", "-.--.-");   
            standardMorseCharactersMap.put("@", ".--.-.");   
            standardMorseCharactersMap.put("*", "...-.-");   
            standardMorseCharactersMap.put("+", ".-.-.");   
            standardMorseCharactersMap.put("%", ".-...");   
            standardMorseCharactersMap.put("\\", "---...");  
            standardMorseCharactersMap.put("\"", ".-..-.");   
            standardMorseCharactersMap.put("'", ".----.");   
            standardMorseCharactersMap.put("!", "=---.");   
            standardMorseCharactersMap.put("$", "...-..-");   
            standardMorseCharactersMap.put(" ", "/");   
        }   
      
        public static String morseEncoder(String input) {   
            String output = "";   
            for (char c : input.toCharArray()) {   
                output += standardMorseCharactersMap.get(String.valueOf(c)) + " ";   
            }   
            return output;   
        }   
      
        public static void main(String[] args) {   
            String input = "yao mu yang";   
            String output = Morse.morseEncoder(input);   
            System.out.println(output);   
        }   
      
    }</STRING>

3、布局文件main.xml 的内容如下：

package basic.android.lesson37;   
      
    import android.app.Activity;   
    import android.content.Context;   
    import android.graphics.Canvas;   
    import android.graphics.Color;   
    import android.graphics.Paint;   
    import android.os.Bundle;   
    import android.util.Log;   
    import android.view.SurfaceHolder;   
    import android.view.SurfaceView;   
    import android.view.View;   
    import android.widget.Button;   
    import android.widget.EditText;   
    import android.widget.LinearLayout;   
      
    public class MainActivity extends Activity {   
         private LinearLayout layout;   
      
         //莫尔斯码数组变量   
          char[] chars;   
         //莫尔斯码数组计数变量   
          int count = 0;   
         //开关标志   
          boolean flag = false;   
         //循环标志   
          boolean loop = false;   
      
         @Override  
         public void onCreate(Bundle savedInstanceState) {   
         super.onCreate(savedInstanceState);   
         setContentView(R.layout.main);   
      
         // 定义UI组件   
         final Button b1 = (Button) findViewById(R.id.Button01);   
         final Button b2 = (Button) findViewById(R.id.Button02);   
      
         final EditText et1 = (EditText) findViewById(R.id.EditText01);   
         final EditText et2 = (EditText) findViewById(R.id.EditText02);   
      
         layout = (LinearLayout) findViewById(R.id.LinearLayout01);   
      
         // 单击转换按钮，转换莫尔斯码   
         b1.setOnClickListener(new View.OnClickListener(){   
      
         @Override  
         public void onClick(View v) {   
             String text = Morse.morseEncoder(et1.getText().toString());   
             et2.setText(text);   
         }   
         });   
      
         // 单击发送信号按钮，把莫尔斯码用灯信号的方式发送出去   
         b2.setOnClickListener(new View.OnClickListener() {   
      
            @Override  
            public void onClick(View v) {   
                //当morse码文本框中有内容的时候就发送灯信号   
                if (et2.getText() != null && et2.getText().toString().length() > 0) {   
                    //把莫尔斯码拆解成一个一个字符   
                    chars = et2.getText().toString().toCharArray();   
                    //计数   
                    count = chars.length;   
                    //创建SurfaceView   
                    LightView light = new LightView(MainActivity.this);   
                    //把SurfaceView动态加入Activity   
                    layout.addView(light);   
                }   
            }   
        });   
        }   
      
        // 信号灯   
        class LightView extends SurfaceView {   
      
           //声明 surfaceHolder 对象   
           SurfaceHolder holder;   
      
           // 构造方法   
           public LightView(Context context) {   
               super(context);   
      
               // 从 SurfaceView 中获取 SurfaceHolder对象   
               holder = this.getHolder();   
               // addCallback 对象   
               holder.addCallback(new SurfaceHolder.Callback() { //创建SurfaceHolder.Callback匿名内部类   
      
                  //在SurfaceHolder.Callback内部类的内部创建它所需要的线程内部类   
                  class LightThread implements Runnable {   
      
                      @Override  
                      public void run() {   
      
                         while (loop) {   
      
                            if (count > 0) {   
                                Log.i("yao", "" + count);   
                                String s = String.valueOf(chars[chars.length - count]);   
                                // 锁定canvas,开始绘图   
                                Canvas canvas = holder.lockCanvas(null);   
      
                                Paint paint = new Paint();   
                                paint.setAntiAlias(true);   
      
                                //清屏幕   
                                paint.setColor(Color.BLACK);   
                                canvas.drawRect(0, 0, 480, 480, paint);                                                            
      
                                //标志位是真的时候关一下灯   
                                if(flag){   
                                    sleep(2);   
                                    paint.setColor(Color.BLACK);   
                                }else{ //为假的时候就亮灯   
                                    // di 亮2个时间点   
                                    if (s.equalsIgnoreCase(".")) {   
                                        sleep(2);   
                                        paint.setColor(Color.YELLOW);   
                                    } else if(s.equalsIgnoreCase("-")) {   
                                        // dah 亮4个时间点   
                                        sleep(4);   
                                        paint.setColor(Color.YELLOW);   
                                    }else if(s.equalsIgnoreCase(" ")){   
                                        // 空格 亮2个时间点   
                                        sleep(2);   
                                        paint.setColor(Color.BLACK);   
                                    }else if(s.equalsIgnoreCase("/")){   
                                        // 单词之间的空白亮2个时间点   
                                        sleep(2);   
                                        paint.setColor(Color.BLACK);   
                                    }else{   
                                        // 出问题的时候亮红灯   
                                        sleep(2);   
                                        paint.setColor(Color.RED);   
                                    }   
                                    count--;   
                                }   
                                //绘制灯光   
                                canvas.drawCircle(250.0f, 200.0f, 100, paint);   
      
                                //标准位开关   
                                flag = !flag;      
      
                                // 释放canvas,绘图完毕   
                                holder.unlockCanvasAndPost(canvas);   
                            }   
      
                         }   
      
                      }   
      
                      //休眠   
                      public void sleep(int time){   
                         try {   
                             Thread.sleep(time*80);   
                         } catch (Exception e) {   
                            //no nothing   
                         }   
                     }   
                  }   
      
                  @Override  
                  public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {   
                    // do nothing   
                  }   
      
                  @Override  
                  public void surfaceCreated(SurfaceHolder holder) {   
                     //在SurfaceView被创建的时候执行   
                     new Thread(new LightThread()).start();   
                  }   
      
                  @Override  
                  public void surfaceDestroyed(SurfaceHolder holder) {   
                     loop = false;   
                  }   
              });   
      
              loop = true;   
      
            }   
        }  
    }

5、编译并运行程序，查看结果：

好了，本讲就到这里，下次再见。