使用：

<objectAnimator
    android:propertyName="translateY"
    android:valueType="floatType"
    android:valueFrom="-100"
    android:valueTo="600"
    android:repeatCount="infinite"
    android:repeatMode="reverse"
    android:duration="1500"
    android:interpolator="@android:anim/accelerate_interpolator">
</objectAnimator>

自定義

以accelerate_interpolator為例
在源碼中三椿，對應(yīng)的文件是：

frameworks\base\core\res\res\anim\linear_accelerate.xml
<?xml version="1.0" encoding="utf-8"?>
<!--
/* //device/apps/common/res/anim/linear_interpolator.xml
**
** Copyright 2007, The Android Open Source Project
**
** Licensed under the Apache License, Version 2.0 (the "License"); 
** you may not use this file except in compliance with the License. 
** You may obtain a copy of the License at 
**
**     http://www.apache.org/licenses/LICENSE-2.0 
**
** Unless required by applicable law or agreed to in writing, software 
** distributed under the License is distributed on an "AS IS" BASIS, 
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
** See the License for the specific language governing permissions and 
** limitations under the License.
*/
-->

<accelerateInterpolator/>

frameworks\base\core\java\android\view\animation\AnimationUtils.java
private static Interpolator createInterpolatorFromXml(Resources res, Theme theme, XmlPullParser parser)
        throws XmlPullParserException, IOException {

    BaseInterpolator interpolator = null;

    // Make sure we are on a start tag.
    int type;
    int depth = parser.getDepth();

    while (((type = parser.next()) != XmlPullParser.END_TAG || parser.getDepth() > depth)
            && type != XmlPullParser.END_DOCUMENT) {

        if (type != XmlPullParser.START_TAG) {
            continue;
        }

        AttributeSet attrs = Xml.asAttributeSet(parser);

        String name = parser.getName();

        if (name.equals("linearInterpolator")) {
            interpolator = new LinearInterpolator();
        } else if (name.equals("accelerateInterpolator")) {
            interpolator = new AccelerateInterpolator(res, theme, attrs);
        } else if (name.equals("decelerateInterpolator")) {
            interpolator = new DecelerateInterpolator(res, theme, attrs);
        } else if (name.equals("accelerateDecelerateInterpolator")) {
            interpolator = new AccelerateDecelerateInterpolator();
        } else if (name.equals("cycleInterpolator")) {
            interpolator = new CycleInterpolator(res, theme, attrs);
        } else if (name.equals("anticipateInterpolator")) {
            interpolator = new AnticipateInterpolator(res, theme, attrs);
        } else if (name.equals("overshootInterpolator")) {
            interpolator = new OvershootInterpolator(res, theme, attrs);
        } else if (name.equals("anticipateOvershootInterpolator")) {
            interpolator = new AnticipateOvershootInterpolator(res, theme, attrs);
        } else if (name.equals("bounceInterpolator")) {
            interpolator = new BounceInterpolator();
        } else if (name.equals("pathInterpolator")) {
            interpolator = new PathInterpolator(res, theme, attrs);
        } else {
            throw new RuntimeException("Unknown interpolator name: " + parser.getName());
        }
    }
    return interpolator;
}

可見，最后調(diào)用的是new AccelerateInterpolator ()

frameworks\base\core\java\android\view\animation\AccelerateInterpolator .java
/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.view.animation;

import android.content.Context;
import android.content.res.Resources;
import android.content.res.Resources.Theme;
import android.content.res.TypedArray;
import android.util.AttributeSet;

import com.android.internal.R;
import com.android.internal.view.animation.HasNativeInterpolator;
import com.android.internal.view.animation.NativeInterpolatorFactory;
import com.android.internal.view.animation.NativeInterpolatorFactoryHelper;

/**
 * An interpolator where the rate of change starts out slowly and
 * and then accelerates.
 *
 */
@HasNativeInterpolator
public class AccelerateInterpolator extends BaseInterpolator implements NativeInterpolatorFactory {
    private final float mFactor;
    private final double mDoubleFactor;

    public AccelerateInterpolator() {
        mFactor = 1.0f;
        mDoubleFactor = 2.0;
    }

    /**
     * Constructor
     *
     * @param factor Degree to which the animation should be eased. Seting
     *        factor to 1.0f produces a y=x^2 parabola. Increasing factor above
     *        1.0f  exaggerates the ease-in effect (i.e., it starts even
     *        slower and ends evens faster)
     */
    public AccelerateInterpolator(float factor) {
        mFactor = factor;
        mDoubleFactor = 2 * mFactor;
    }

    public AccelerateInterpolator(Context context, AttributeSet attrs) {
        this(context.getResources(), context.getTheme(), attrs);
    }

    /** @hide */
    public AccelerateInterpolator(Resources res, Theme theme, AttributeSet attrs) {
        TypedArray a;
        if (theme != null) {
            a = theme.obtainStyledAttributes(attrs, R.styleable.AccelerateInterpolator, 0, 0);
        } else {
            a = res.obtainAttributes(attrs, R.styleable.AccelerateInterpolator);
        }

        mFactor = a.getFloat(R.styleable.AccelerateInterpolator_factor, 1.0f);
        mDoubleFactor = 2 * mFactor;
        setChangingConfiguration(a.getChangingConfigurations());
        a.recycle();
    }

    public float getInterpolation(float input) {
        if (mFactor == 1.0f) {
            return input * input;
        } else {
            return (float)Math.pow(input, mDoubleFactor);
        }
    }

    /** @hide */
    @Override
    public long createNativeInterpolator() {
        return NativeInterpolatorFactoryHelper.createAccelerateInterpolator(mFactor);
    }
}

通過重寫getInterpolation(float input)來控制動畫播放

自定義