1.概念

旋转动画，创建动画时需要指定动画开始和结束时的旋转角度，以及动画持续时间；同时由于旋转时以不同的点作为中心会产生不同的效果，因此需要通过pivotX 和 pivotY 指定旋转中心的坐标。

2.创建

XML：

<?xml version="1.0" encoding="utf-8"?>
<rotate
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:fromDegrees="-180"
    android:toDegrees="0"
    android:pivotX="50%"
    android:pivotY="50%"
    android:fillAfter="true"
    android:duration="200" />

Java：

                //RotateAnimation rotateAnimation = new RotateAnimation(0, 360, 0.5f, 0.5f);
                RotateAnimation rotateAnimation = new RotateAnimation(0, 360, RotateAnimation.RELATIVE_TO_SELF,0.5f,RotateAnimation.RELATIVE_TO_SELF, 0.5f);
                //动画播放的时间间隔
                rotateAnimation.setDuration(3000);
                //动画播放的重复次数
                rotateAnimation.setRepeatCount(2);
                rotateAnimation.setRepeatMode(RESTART);
                imageView.startAnimation(rotateAnimation);

3.构造函数解析

RotateAnimation有三个构造函数，下面就对这些参数进行解析：

    /**
     * Constructor to use when building a RotateAnimation from code.
     * Default pivotX/pivotY point is (0,0).
     * 
     * @param fromDegrees Rotation offset to apply at the start of the
     *        animation.
     * 
     * @param toDegrees Rotation offset to apply at the end of the animation.
     */
    public RotateAnimation(float fromDegrees, float toDegrees) {
        mFromDegrees = fromDegrees;
        mToDegrees = toDegrees;
        mPivotX = 0.0f;
        mPivotY = 0.0f;
    }

    /**
     * Constructor to use when building a RotateAnimation from code
     * 
     * @param fromDegrees Rotation offset to apply at the start of the
     *        animation.
     * 
     * @param toDegrees Rotation offset to apply at the end of the animation.
     * 
     * @param pivotX The X coordinate of the point about which the object is
     *        being rotated, specified as an absolute number where 0 is the left
     *        edge.
     * @param pivotY The Y coordinate of the point about which the object is
     *        being rotated, specified as an absolute number where 0 is the top
     *        edge.
     */
    public RotateAnimation(float fromDegrees, float toDegrees, float pivotX, float pivotY) {
        mFromDegrees = fromDegrees;
        mToDegrees = toDegrees;

        mPivotXType = ABSOLUTE;
        mPivotYType = ABSOLUTE;
        mPivotXValue = pivotX;
        mPivotYValue = pivotY;
        initializePivotPoint();
    }

    /**
     * Constructor to use when building a RotateAnimation from code
     * 
     * @param fromDegrees Rotation offset to apply at the start of the
     *        animation.
     * 
     * @param toDegrees Rotation offset to apply at the end of the animation.
     * 
     * @param pivotXType Specifies how pivotXValue should be interpreted. One of
     *        Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or
     *        Animation.RELATIVE_TO_PARENT.
     * @param pivotXValue The X coordinate of the point about which the object
     *        is being rotated, specified as an absolute number where 0 is the
     *        left edge. This value can either be an absolute number if
     *        pivotXType is ABSOLUTE, or a percentage (where 1.0 is 100%)
     *        otherwise.
     * @param pivotYType Specifies how pivotYValue should be interpreted. One of
     *        Animation.ABSOLUTE, Animation.RELATIVE_TO_SELF, or
     *        Animation.RELATIVE_TO_PARENT.
     * @param pivotYValue The Y coordinate of the point about which the object
     *        is being rotated, specified as an absolute number where 0 is the
     *        top edge. This value can either be an absolute number if
     *        pivotYType is ABSOLUTE, or a percentage (where 1.0 is 100%)
     *        otherwise.
     */
    public RotateAnimation(float fromDegrees, float toDegrees, int pivotXType, float pivotXValue,
            int pivotYType, float pivotYValue) {
        mFromDegrees = fromDegrees;
        mToDegrees = toDegrees;

        mPivotXValue = pivotXValue;
        mPivotXType = pivotXType;
        mPivotYValue = pivotYValue;
        mPivotYType = pivotYType;
        initializePivotPoint();
    }

• fromDegrees 动画开始时的旋转角度

• toDegrees 动画结束时的旋转角度

• pivotXType 动画在 X 轴的旋转模式，即相对于物件的位置类型，取值是Animation.ABSOLUTE、Animation.RELATIVE_TO_SELF、Animation.RELATIVE_TO_PARENT
• pivotXValue 动画相对于物件的 X 坐标开始位置
• pivotYType 动画在 Y 轴的旋转模式，即相对于物件的位置类型，取值是Animation.ABSOLUTE、Animation.RELATIVE_TO_SELF、Animation.RELATIVE_TO_PARENT
• pivotYValue 动画相对于物件的 Y 坐标开始位置