1.联网权限

    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.INTERNET" />

2.主界面网络下载

package com.example.glidedownload;

import android.Manifest;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.graphics.drawable.Drawable;
import android.net.Uri;
import android.os.Environment;
import android.provider.MediaStore;
import android.support.v4.app.ActivityCompat;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

import com.bumptech.glide.Glide;
import com.bumptech.glide.load.engine.DiskCacheStrategy;
import com.bumptech.glide.request.animation.GlideAnimation;
import com.bumptech.glide.request.target.SimpleTarget;


import java.io.File;
import java.util.Calendar;
import java.util.concurrent.ExecutionException;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private Context mContext;
    private Button download;
    private ImageView img;
    private File target = null;
    // public static String PICTURE_s04 = "https://ss0.bdstatic.com/70cFvHSh_Q1YnxGkpoWK1HF6hhy/it/u=339074543,1379749639&fm=26&gp=0.jpg";
    //   public static String PICTURE_04 = "https://ss0.bdstatic.com/70cFvHSh_Q1YnxGkpoWK1HF6hhy/it/u=1774420118,989846740&fm=26&gp=0.jpg";
    public static String PIsCTURE_01 = "https://ss3.bdstatic.com/70cFv8Sh_Q1YnxGkpoWK1HF6hhy/it/u=1652123795,1945063222&fm=26&gp=0.jpg";
    public static String PIsssCTURE_01 = "https://ss1.bdstatic.com/70cFuXSh_Q1YnxGkpoWK1HF6hhy/it/u=3574546774,2747680979&fm=11&gp=0.jpg";
    public static String PICTURE_01 = "https://ss2.bdstatic.com/70cFvnSh_Q1YnxGkpoWK1HF6hhy/it/u=2807156066,2009521216&fm=11&gp=0.jpg";

    private String path;


    /*    private static final String URL =
            "https://uploadbeta.com/api/pictures/random/?key=BingEverydayWallpaperPicture";*/
    public static String FILENAME = Environment.getExternalStorageDirectory() + "/Download/picture.jpg";
    private static final String TAG = "MainActivity";

    private static final int REQUEST_EXTERNAL_STORAGE = 1;
    private static String[] PERMISSIONS_STORAGE = {
            Manifest.permission.READ_EXTERNAL_STORAGE,
            Manifest.permission.WRITE_EXTERNAL_STORAGE
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mContext = this;
        download = findViewById(R.id.download);
        img = findViewById(R.id.img);

        target = new File(FILENAME);
        download.setOnClickListener(this);
        verifyStoragePermissions(this);
        if (target.exists()) {
            Glide.with(mContext).load(target).into(img);
        }
    }


    /**
     * 在对sd卡进行读写操作之前调用这个方法
     * Checks if the app has permission to write to device storage
     * If the app does not has permission then the user will be prompted to grant permissions
     */
    public static void verifyStoragePermissions(Activity activity) {
        // Check if we have write permission
        int permission = ActivityCompat.checkSelfPermission(activity,
                Manifest.permission.WRITE_EXTERNAL_STORAGE);
        if (permission != PackageManager.PERMISSION_GRANTED) {
            // We don't have permission so prompt the user
            ActivityCompat.requestPermissions(activity, PERMISSIONS_STORAGE,
                    REQUEST_EXTERNAL_STORAGE);
        }
    }

    @Override
    public void onClick(View v) {
        if (v.getId() == R.id.download) {
            new Thread(new MyRunnable()).start();
        }
    }

    class MyRunnable implements Runnable {
        @Override
        public void run() {
            downloadImage();
            getImageView();
        }
    }

    private void getImageView() {
        //  val saveAs = "Your_Created_Image_File_Path"
        Uri contentUri = Uri.fromFile(new File(path));
        Log.e(TAG, "onGetMessage_like: " + path);
        Intent mediaScanIntent = new Intent(Intent.ACTION_MEDIA_SCANNER_SCAN_FILE, contentUri);
        sendBroadcast(mediaScanIntent);
    }

    private String downloadImage() {
        Glide.get(getApplicationContext()).clearDiskCache();
        File file = null;
        try {
            file = Glide.with(mContext)
                    .load(PICTURE_01)
                    .downloadOnly(96, 96)
                    .get();
        } catch (Exception e) {
            e.printStackTrace();
        }
        path = FileUtil.copy(file, target);
        //    MediaStore.Images.Media.insertImage(getContentResolver(),.getPath(),"cameraPhoto", "Camera Pic Sample App Took");
        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                Glide.with(mContext)
                        .load(target)
                        .diskCacheStrategy(DiskCacheStrategy.NONE)
                        .skipMemoryCache(true)
                        .into(img);
            }
        });
        return path;
    }


}

3.文件类

package com.example.glidedownload;

import android.os.Environment;
import android.util.Log;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

/**
 * Created by zhc on 2019/12/19.
 */
public class FileUtil {

    private static final String TAG = "FileUtil";

    /**
     * 复制文件
     * @param filename 文件名
     * @param bytes 数据
     */
    public static void copy(String filename, byte[] bytes) {
        try {
            //如果手机已插入sd卡,且app具有读写sd卡的权限
            if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
                FileOutputStream output = null;
                output = new FileOutputStream(filename);
                output.write(bytes);
                Log.i(TAG,"copy success, " + filename);
                output.close();
            } else {
                Log.i(TAG, "copy fail, " + filename);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    /**
     * 复制文件
     *
     * @param source 输入文件
     * @param target 输出文件
     */
    public static String copy(File source, File target) {
        FileInputStream fileInputStream = null;
        FileOutputStream fileOutputStream = null;
        try {
            fileInputStream = new FileInputStream(source);
            fileOutputStream = new FileOutputStream(target);
            byte[] buffer = new byte[1024];
            while (fileInputStream.read(buffer) > 0) {
                fileOutputStream.write(buffer);
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (fileInputStream != null) {
                    fileInputStream.close();
                }
                if (fileOutputStream != null) {
                    fileOutputStream.close();
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        return target.getPath();
    }

}

4.打开相册，选择全部图片，可以看到刚刚下载的图片

end