feat: 优化代码

app/src/main/java/io/legado/app/help/storage/Backup.kt

@@ -54,6 +54,7 @@ object Backup {
     suspend fun backup(context: Context, path: String = legadoPath) {
         context.putPrefLong(PreferKey.lastBackup, System.currentTimeMillis())
         withContext(IO) {
+            synchronized(this@Backup) {
                 writeListToJson(App.db.bookDao().all, "bookshelf.json", backupPath)
                 writeListToJson(App.db.bookGroupDao().all, "bookGroup.json", backupPath)
                 writeListToJson(App.db.bookSourceDao().all, "bookSource.json", backupPath)
@@ -86,6 +87,7 @@ object Backup {
                 }
             }
         }
+    }
 
     private fun writeListToJson(list: List<Any>, fileName: String, path: String) {
         if (list.isNotEmpty()) {
@@ -96,6 +98,7 @@ object Backup {
 
     @Throws(java.lang.Exception::class)
     private fun copyBackup(context: Context, uri: Uri) {
+
         DocumentFile.fromTreeUri(context, uri)?.let { treeDoc ->
             for (fileName in backupFileNames) {
                 val file = File(backupPath + File.separator + fileName)

app/src/main/java/io/legado/app/help/storage/OldBook.kt

@@ -40,7 +40,6 @@ object OldBook {
             book.durChapterTitle = jsonItem.readString("$.durChapterName")
             book.durChapterPos = jsonItem.readInt("$.durChapterPage") ?: 0
             book.durChapterTime = jsonItem.readLong("$.finalDate") ?: 0
-            book.group = jsonItem.readInt("$.group") ?: 0
             book.intro = jsonItem.readString("$.bookInfoBean.introduce")
             book.latestChapterTitle = jsonItem.readString("$.lastChapterName")
             book.lastCheckCount = jsonItem.readInt("$.newChapters") ?: 0