Android View如何绘制

@Override
  protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
  }

public class MyView extends View {

  private Paint paint;
  public MyView(Context context, AttributeSet attrs) {
    super(context, attrs);
    init();
  }

  private void init() {
    paint=new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setColor(Color.RED);
    paint.setStrokeWidth(5);
    paint.setTextSize(28);
    
  }

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    setMeasuredDimension(measureWidth(widthMeasureSpec),
        measureWidth(heightMeasureSpec));
  }

  public int measureWidth(int measureSpec) {
    int result = 0;
    int specMode = MeasureSpec.getMode(measureSpec);
    int specSize = MeasureSpec.getSize(measureSpec);
    if (specMode == MeasureSpec.EXACTLY) {
      result = specSize;
    } else {
      result = 200;
      if (specMode == MeasureSpec.AT_MOST) {
        result = Math.min(specSize, result);
      }
    }
    return result;
  }
  
  @Override
  protected void onDraw(Canvas canvas) {
    canvas.drawText("中国", 0, 80, paint);
    super.onDraw(canvas);
  }
}