自定义View的封装

通过上一个博文的自定义View的编写后，发现代码其实挺复杂的，所有这里通过对代码进一步的优化，即用到了java的一个重要的特点：封装。通过对父类的方法进行封装，然后在子类继承后实现相应的函数即可，达到了代码的优化。

MainActivity.java

 1 package com.example.myview;
 2
 3 import android.os.Bundle;
 4 import android.app.Activity;
 5 import android.view.Menu;
 6
 7 public class MainActivity extends Activity {
 8
 9     @Override
10     protected void onCreate(Bundle savedInstanceState) {
11         super.onCreate(savedInstanceState);
12         setContentView(R.layout.activity_main);
13         //setContentView(new Myview(this));
14     }
15 }

activity_main.xml

 1 <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     xmlns:tools="http://schemas.android.com/tools"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     tools:context=".MainActivity" >
 6     <com.example.myview.SubClass
 7         android:layout_width="match_parent"
 8         android:layout_height="match_parent"
 9          />
10 </FrameLayout>

封装后的TestClass.java

 1 package com.example.myview;
 2
 3 import java.util.Random;
 4
 5 import android.content.Context;
 6 import android.graphics.Canvas;
 7 import android.graphics.Paint;
 8 import android.graphics.RectF;
 9 import android.util.AttributeSet;
10 import android.view.View;
11
12 public abstract class TestClass extends View{
13
14     private MyThread thread;
15
16     public TestClass(Context context, AttributeSet attrs) {
17         super(context, attrs);
18     }
19
20     public TestClass(Context context) {
21         super(context);
22     }
23
24     protected abstract void drawSub(Canvas canvas);
25     protected abstract void logic();
26
27     protected void onDraw(Canvas canvas){
28         if(thread==null){
29             thread = new MyThread();
30             thread.start();
31         }else{
32             drawSub(canvas);
33         }
34     }
35
36
37     class MyThread extends Thread{
38         @Override
39         public void run() {
40             while(true){
41                 logic();
42                 postInvalidate();
43                 try {
44                     Thread.sleep(30);
45                 } catch (InterruptedException e) {
46                     e.printStackTrace();
47                 }
48             }
49
50         }
51     }
52
53 }

SubClass.java :继承自TestClass.java

 1 package com.example.myview;
 2
 3 import java.util.Random;
 4
 5 import android.content.Context;
 6 import android.graphics.Canvas;
 7 import android.graphics.Paint;
 8 import android.graphics.RectF;
 9 import android.util.AttributeSet;
10
11
12 public class SubClass extends TestClass{
13
14     private Paint paint = new Paint();
15     private float rx = 0;
16     private RectF rectF = new RectF(0,60,100,160);
17     private float sweepAngel = 0;
18     Random rand = new Random();
19
20     public SubClass(Context context) {
21         super(context);
22     }
23
24     public SubClass(Context context, AttributeSet attrs) {
25         super(context, attrs);
26     }
27
28     @Override
29     protected void drawSub(Canvas canvas) {
30         paint.setTextSize(30);
31         canvas.drawText("LogicView", rx, 30, paint);
32
33         canvas.drawArc(rectF,0,sweepAngel,true,paint);
34     }
35
36     @Override
37     protected void logic() {
38         rx++;
39         if(rx > getWidth()){
40             rx = 0 - paint.measureText("LogicView");
41         }
42
43         sweepAngel ++ ;
44
45         if(sweepAngel > 360){
46             sweepAngel = 0;
47         }
48         int r = rand.nextInt(256);
49         int g = rand.nextInt(256);
50         int b = rand.nextInt(256);
51         paint.setARGB(255, r, g, b);
52     }
53
54 }

通过运行达到了一样的效果。

但是有些人会说，这样写的话不是更加复杂，而且代码增多了？

其实不然，通过对父类TestClass.java进行封装后，我们所要做的工作其实只有SubClass.java（继承自父类TestClass.java），然后实现类中的2个方法protected void drawSub(Canvas canvas)和protected void logic()即可，而线程的实现已经在父类TestClass.java中实现了，而不用再实现。当工作量很大的时候，这是相当有利的。