/**
     * 保存bitmap到本地
     *
     * @param bitmap Bitmap
     */
    public static void saveBitmap(Bitmap bitmap, String path) {
        String savePath;
        File filePic;
        if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) {
            savePath = path;
        } else {
            Log.e("tag", "saveBitmap failure : sdcard not mounted");
            return;
        }
        try {
            filePic = new File(savePath);
            if (!filePic.exists()) {
                filePic.getParentFile().mkdirs();
                filePic.createNewFile();
            }
            FileOutputStream fos = new FileOutputStream(filePic);
            bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fos);
            fos.flush();
            fos.close();
        } catch (IOException e) {
            Log.e("tag", "saveBitmap: " + e.getMessage());
            return;
        }
        Log.i("tag", "saveBitmap success: " + filePic.getAbsolutePath());
    }

 
    /**
     * API 29及以下保存圖片到相冊的方法
     *
     * @param toBitmap 要保存的圖片
     */
    private void saveImage(Bitmap toBitmap) {
        String insertImage = MediaStore.Images.Media.insertImage(getContentResolver(), toBitmap, "壁紙", "搜索貓相關圖片后保存的圖片");
        if (!TextUtils.isEmpty(insertImage)) {
            Toast.makeText(this, "圖片保存成功!" + insertImage, Toast.LENGTH_SHORT).show();
            Log.e("打印保存路徑", insertImage + "-");
        }
    }

  /**
     * API29 中的最新保存圖片到相冊的方法
     */
    private void saveImage29(Bitmap toBitmap) {
        //開始一個新的進程執行保存圖片的操作
        Uri insertUri = getContentResolver().insert(MediaStore.Images.Media.EXTERNAL_CONTENT_URI, new ContentValues());
        //使用use可以自動關閉流
        try {
            OutputStream outputStream = getContentResolver().openOutputStream(insertUri, "rw");
            if (toBitmap.compress(Bitmap.CompressFormat.JPEG, 90, outputStream)) {
                Log.e("保存成功", "success");
            } else {
                Log.e("保存失敗", "fail");
            }
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

package com.xiayiye.jetpackstudy.gallery


import android.Manifest
import android.content.ContentValues
import android.content.pm.PackageManager
import android.graphics.Bitmap
import android.os.Build
import android.os.Bundle
import android.provider.MediaStore
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Toast
import androidx.core.content.ContextCompat
import androidx.core.graphics.drawable.toBitmap
import androidx.core.view.get
import androidx.fragment.app.Fragment
import androidx.lifecycle.lifecycleScope
import androidx.recyclerview.widget.RecyclerView
import androidx.viewpager2.widget.ViewPager2
import com.xiayiye.jetpackstudy.R
import kotlinx.android.synthetic.main.fragment_view_pager2_image.*
import kotlinx.android.synthetic.main.pager_photo_view.view.*
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.MainScope
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext

/**
 * 顯示輪播大圖和保存圖片的頁面
 */

class ViewPager2ImageFragment : Fragment() {
    companion object {
        const val REQUEST_WRITE_EXTERNAL_STORAGE_CODE = 1000
    }

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        return inflater.inflate(R.layout.fragment_view_pager2_image, container, false)
    }

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        val photoList = arguments?.getParcelableArrayList<PhotoItem>("photo_list")
        val currentPosition = arguments?.getInt("photo_position", 0)
        PagerPhotoListAdapter().apply {
            vp2Banner.adapter = this
            submitList(photoList)
        }
        //設置輪播圖片后的滑動當前頁
        vp2Banner.registerOnPageChangeCallback(object : ViewPager2.OnPageChangeCallback() {
            override fun onPageSelected(position: Int) {
                super.onPageSelected(position)
                tvShowImagePage.text =
                    StringBuffer().append(position + 1).append("/").append(photoList?.size)
            }
        })
        //設置 ViewPager2 的當前頁要在設置 ViewPager2 的數據后在設置當前頁面,否則不生效
        vp2Banner.setCurrentItem(currentPosition ?: 0, false)
        //設置縱向滾動的方法
        vp2Banner.orientation = ViewPager2.ORIENTATION_VERTICAL
        //保存圖片的方法
        ivSaveImg.setOnClickListener {
            if (Build.VERSION.SDK_INT < 29 && ContextCompat.checkSelfPermission(
                    requireContext(), Manifest.permission.WRITE_EXTERNAL_STORAGE
                ) != PackageManager.PERMISSION_GRANTED
            ) {
                requestPermissions(
                    arrayOf<String>(Manifest.permission.WRITE_EXTERNAL_STORAGE),
                    REQUEST_WRITE_EXTERNAL_STORAGE_CODE
                )
            } else {
                viewLifecycleOwner.lifecycleScope.launch { saveImage29() }
            }
        }
    }

    override fun onRequestPermissionsResult(
        requestCode: Int,
        permissions: Array<out String>,
        grantResults: IntArray
    ) {
        super.onRequestPermissionsResult(requestCode, permissions, grantResults)
        if (requestCode == REQUEST_WRITE_EXTERNAL_STORAGE_CODE && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
            //權限申請成功可以保存圖片
            viewLifecycleOwner.lifecycleScope.launch { saveImage29() }
        }
    }

    /**
     * 保存圖片到相冊的方法
     *  API29 后此方法已廢棄
     */
    private fun saveImage() {
        val holder =
            (vp2Banner[0] as RecyclerView).findViewHolderForAdapterPosition(vp2Banner.currentItem) as PagerPhotoListAdapter.PagerPhotoViewHolder
        val toBitmap = holder.itemView.ivPagerView.drawable.toBitmap()
        val insertImage = MediaStore.Images.Media.insertImage(
            requireActivity().contentResolver, toBitmap, "壁紙", "搜索貓相關圖片后保存的圖片"
        )
        if (insertImage.isNotEmpty()) {
            Toast.makeText(requireActivity(), "圖片保存成功！-${insertImage}", Toast.LENGTH_SHORT).show()
        } else {
            Toast.makeText(requireActivity(), "圖片保存失敗！}", Toast.LENGTH_SHORT).show()
        }
    }

    /**
     * API29 中的最新保存圖片到相冊的方法
     */
    private suspend fun saveImage29() {
        //開始一個新的進程執行保存圖片的操作
        withContext(Dispatchers.IO) {
            val holder =
                (vp2Banner[0] as RecyclerView).findViewHolderForAdapterPosition(vp2Banner.currentItem) as PagerPhotoListAdapter.PagerPhotoViewHolder
            val toBitmap = holder.itemView.ivPagerView.drawable.toBitmap()
            val insertUri = requireActivity().contentResolver.insert(
                MediaStore.Images.Media.EXTERNAL_CONTENT_URI, ContentValues()
            ) ?: kotlin.run {
                showSaveToast("保存失敗！")
                return@withContext
            }
            //使用use可以自動關閉流
            requireActivity().contentResolver.openOutputStream(insertUri).use {
                if (toBitmap.compress(Bitmap.CompressFormat.JPEG, 90, it)) {
                    showSaveToast("保存成功！")
                } else {
                    showSaveToast("保存失敗！")
                }
            }
        }
    }

    /**
     * 顯示保存圖片結果的方法
     */
    private fun showSaveToast(showMsg: String) =
        MainScope().launch {
            Toast.makeText(requireActivity(), showMsg, Toast.LENGTH_SHORT).show()
        }
}