Android设计模式系列(4)--SDK源码之模板方法模式

public class View{
    /**
     * 钩子操作，空实现
     */
    protected void onDraw(Canvas canvas) {
    }
 
    /**
     *钩子操作，空实现
     */
    protected void dispatchDraw(Canvas canvas) {
    }
 
    //算法骨架
    public void draw(Canvas canvas) {
       if (!verticalEdges && !horizontalEdges) {
            // 步骤1
            if (!dirtyOpaque) onDraw(canvas);
 
            // 步骤2
            dispatchDraw(canvas);
 
            // 步骤3
            onDrawScrollBars(canvas);
 
            return;
        }
    }
    //... ...
}

public class TextView{
    @Override
    protected void onDraw(Canvas canvas) {
        //大量自定义实现代码
    }
}

public class MyView extends View {
 
    public MyView(Context context) {
        super(context);
    }
 
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
    }
 
    @Override
    protected void dispatchDraw(Canvas canvas) {
        super.dispatchDraw(canvas);
    }
     
}