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

 package com.example.myview;

 import android.os.Bundle;
 import android.app.Activity;
 import android.view.Menu;

 public class MainActivity extends Activity {

     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_main);
         //setContentView(new Myview(this));
     }
 }

activity_main.xml

 <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:tools="http://schemas.android.com/tools"
     android:layout_width="match_parent"
     android:layout_height="match_parent"
     tools:context=".MainActivity" >
     <com.example.myview.SubClass
         android:layout_width="match_parent"
         android:layout_height="match_parent"
          />
 </FrameLayout>

封装后的TestClass.java

 package com.example.myview;

 import java.util.Random;

 import android.content.Context;
 import android.graphics.Canvas;
 import android.graphics.Paint;
 import android.graphics.RectF;
 import android.util.AttributeSet;
 import android.view.View;

 public abstract class TestClass extends View{

     private MyThread thread;

     public TestClass(Context context, AttributeSet attrs) {
         super(context, attrs);
     }

     public TestClass(Context context) {
         super(context);
     }

     protected abstract void drawSub(Canvas canvas);
     protected abstract void logic();

     protected void onDraw(Canvas canvas){
         if(thread==null){
             thread = new MyThread();
             thread.start();
         }else{
             drawSub(canvas);
         }
     }

     class MyThread extends Thread{
         @Override
         public void run() {
             while(true){
                 logic();
                 postInvalidate();
                 try {
                     Thread.sleep();
                 } catch (InterruptedException e) {
                     e.printStackTrace();
                 }
             }

         }
     }

 }

SubClass.java :继承自TestClass.java

 package com.example.myview;

 import java.util.Random;

 import android.content.Context;
 import android.graphics.Canvas;
 import android.graphics.Paint;
 import android.graphics.RectF;
 import android.util.AttributeSet;

 public class SubClass extends TestClass{

     private Paint paint = new Paint();
     private float rx = ;
     private RectF rectF = new RectF(,,,);
     private float sweepAngel = ;
     Random rand = new Random();

     public SubClass(Context context) {
         super(context);
     }

     public SubClass(Context context, AttributeSet attrs) {
         super(context, attrs);
     }

     @Override
     protected void drawSub(Canvas canvas) {
         paint.setTextSize();
         canvas.drawText("LogicView", rx, , paint);

         canvas.drawArc(rectF,,sweepAngel,true,paint);
     }

     @Override
     protected void logic() {
         rx++;
         if(rx > getWidth()){
             rx =  - paint.measureText("LogicView");
         }

         sweepAngel ++ ;

         if(sweepAngel > ){
             sweepAngel = ;
         }
         int r = rand.nextInt();
         int g = rand.nextInt();
         int b = rand.nextInt();
         paint.setARGB(, r, g, b);
     }

 }

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。