AssetManager读取assets下多张图片资源输出到ImageView动画

AssetManager读取assets下多张图片资源输出到ImageView动画

这里面有几个要点和环节需要注意：
1，AssetManager读取事先放置到assets目录下的原始图片资源文件，组装成Android的Bitmap数组。
文件结构如图：

2，把1中读取到的Bitmap数组每隔一个较小时间内(如25ms)不间断循环设置到ImageView里面，从而在视觉上形成一种动画效果。

代码：

package zhangphil.test;

import android.content.res.AssetManager;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.support.v7.app.AppCompatActivity;
import android.widget.ImageView;

import java.io.InputStream;
import java.util.concurrent.TimeUnit;

public class AnimationActivity extends AppCompatActivity {
    private boolean mStartLoadingAnimation = false;
    private ImageView mImageView;

    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.animation_activity);
        mImageView = findViewById(R.id.image);

        mStartLoadingAnimation = true;
        loadingAnimation();
    }

    private void loadingAnimation() {
        new Thread(new Runnable() {
            @Override
            public void run() {
                Bitmap[] bitmaps = getBimaps();
                if (bitmaps == null || bitmaps.length == 0) {
                    return;
                }

                int i = 0;
                while (mStartLoadingAnimation) {
                    mImageView.setImageBitmap(bitmaps[i++ % bitmaps.length]);

                    try {
                        TimeUnit.MILLISECONDS.sleep(25);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
        }).start();
    }

    private Bitmap[] getBimaps() {
        final String parentPath = "loading";

        Bitmap[] bitmaps = null;
        AssetManager am = getAssets();
        try {
            String[] files = am.list(parentPath);
            bitmaps = new Bitmap[files.length];
            for (int i = 0; i < files.length; i++) {
                InputStream is = am.open(parentPath + "/" + files[i]);
                bitmaps[i] = BitmapFactory.decodeStream(is);
                is.close();
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

        return bitmaps;
    }
}