日前做專案重構，想在酒店介紹圖片展示裡增加些動畫，覺得淡入淡出的效果不錯，上網問度娘，找到一篇部落格寫的是我需要的答案  ，但是他是重寫一個Relativelayout，有幾張圖片就新建幾個Imageview，再把這些Imageview加到Relaytivelayout裡邊去，根據顯示的第幾張圖片，設定透明度來實現效果，看完之後覺得這種方法不太理想，少的幾張圖片倒不會出現什麼問題，但是圖片一旦多了，就可能造成記憶體溢位，於是我想到用兩張圖片交替出現通過屬性動畫來實現這個需求,下面貼上關鍵程式碼，

   主Activity

package com.lyf.gradientdemo;

import android.animation.Animator;
import android.animation.AnimatorInflater;
import android.animation.AnimatorListenerAdapter;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.widget.ImageView;

import java.util.Timer;
import java.util.TimerTask;

public class MainActivity extends AppCompatActivity {
    private ImageView image1, image2;
    private ImageView[] imageViews = new ImageView[2];
    private int currentpos = 1;
    private Animator animator1, animator2;
    private int image[] = {R.mipmap.a04, R.mipmap.a05, R.mipmap.a06, R.mipmap.a07, R.mipmap.a08, R.mipmap.a09};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        image1 = (ImageView) findViewById(R.id.image1);
        image2 = (ImageView) findViewById(R.id.image2);
        imageViews[0] = image1;
        imageViews[1] = image2;
        image1.setImageResource(image[0]);
        image2.setImageResource(image[1]);
        animator1 = AnimatorInflater.loadAnimator(this, R.animator.out_anim);
        animator2 = AnimatorInflater.loadAnimator(this, R.animator.in_anim);
        animator1.addListener(new AnimatorListenerAdapter() {
            @Override
            public void onAnimationEnd(Animator animation) {
                currentpos++;
                if (currentpos % imageViews.length == 0) {
                    image1.setImageResource(image[currentpos % image.length]);
                } else if (currentpos % imageViews.length == 1) {
                    image2.setImageResource(image[currentpos % image.length]);
                }
                super.onAnimationEnd(animation);
            }

            @Override
            public void onAnimationStart(Animator animation) {
                super.onAnimationStart(animation);
            }
        });
        new Timer().schedule(new TimerTask() {
            @Override
            public void run() {
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        animator1.setTarget(imageViews[(currentpos + 1) % imageViews.length]);
                        animator2.setTarget(imageViews[currentpos % imageViews.length]);
                        animator1.start();
                        animator2.start();
                    }
                });
            }
        }, 5000, 5000);
    }
}
 

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">

    <ImageView
android:id="@+id/image2"
android:layout_width="match_parent"
android:layout_height="match_parent"
 
android:alpha="0" />

    <ImageView
android:id="@+id/image1"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</RelativeLayout>

in_anim.xml

<objectAnimator xmlns:android="http://schemas.android.com/apk/res/android"
android:propertyName="alpha"
android:valueFrom="0"
 
android:duration="2000"
android:valueTo="1"
android:valueType="floatType" />

out_anim.xml

<objectAnimator xmlns:android="http://schemas.android.com/apk/res/android"
android:duration="2000"
android:propertyName="alpha"
android:valueFrom="1"
android:valueTo="0"
android:valueType="floatType" />