feat: 优化代码

app/src/main/java/io/legado/app/ui/download/DownloadActivity.kt

@@ -131,7 +131,7 @@ class DownloadActivity : VMBaseActivity<DownloadViewModel>(R.layout.activity_dow
             exportRequestCode -> if (resultCode == Activity.RESULT_OK) {
                 data?.data?.let { uri ->
                     adapter.getItem(exportPosition)?.let {
-                        viewModel.export(it, uri)
+                        viewModel.export(uri, it)
                     }
                 }
             }

app/src/main/java/io/legado/app/ui/download/DownloadAdapter.kt

@@ -7,6 +7,7 @@ import io.legado.app.base.adapter.SimpleRecyclerAdapter
 import io.legado.app.data.entities.Book
 import kotlinx.android.synthetic.main.item_download.view.*
 import org.jetbrains.anko.sdk27.listeners.onClick
+import org.jetbrains.anko.toast
 
 
 class DownloadAdapter(context: Context, private val callBack: CallBack) :
@@ -36,9 +37,16 @@ class DownloadAdapter(context: Context, private val callBack: CallBack) :
 
     override fun registerListener(holder: ItemViewHolder) {
         holder.itemView.tv_export.onClick {
+            getItem(holder.layoutPosition)?.let {
+                val cacheSize = cacheChapters[it.bookUrl]?.size ?: 0
+                if (cacheSize < it.totalChapterNum) {
+                    context.toast("未下载完成")
+                } else {
                     callBack.export(holder.layoutPosition)
                 }
             }
+        }
+    }
 
     interface CallBack {
         fun export(position: Int)

app/src/main/java/io/legado/app/ui/download/DownloadViewModel.kt

@@ -2,6 +2,8 @@ package io.legado.app.ui.download
 
 import android.app.Application
 import android.net.Uri
+import androidx.documentfile.provider.DocumentFile
+import io.legado.app.App
 import io.legado.app.base.BaseViewModel
 import io.legado.app.data.entities.Book
 
@@ -9,11 +11,19 @@ import io.legado.app.data.entities.Book
 class DownloadViewModel(application: Application) : BaseViewModel(application) {
 
 
-    fun export(book: Book, uri: Uri) {
+    fun export(uri: Uri, book: Book) {
         execute {
+            DocumentFile.fromTreeUri(context, uri)
+                ?.createFile("txt", book.name)
+                ?.let {
+                    context.contentResolver.openOutputStream(it.uri)?.let {
+                        App.db.bookChapterDao().getChapterList(book.bookUrl).forEach {
 
                         }
                     }
+                }
+        }
+    }
 
 
 }