diff --git a/app/src/main/java/io/legado/app/ui/book/local/ImportBookAdapter.kt b/app/src/main/java/io/legado/app/ui/book/local/ImportBookAdapter.kt
index 800faf5e2..91d35d437 100644
--- a/app/src/main/java/io/legado/app/ui/book/local/ImportBookAdapter.kt
+++ b/app/src/main/java/io/legado/app/ui/book/local/ImportBookAdapter.kt
@@ -51,7 +51,7 @@ class ImportBookAdapter(context: Context, val callBack: CallBack) :
                     }
                     llBrief.visible()
                     tvTag.text = item.name.substringAfterLast(".")
-                    tvSize.text = StringUtils.toSize(item.size)
+                    tvSize.text = ConvertUtils.formatFileSize(item.size)
                     tvDate.text = AppConst.dateFormat.format(item.date)
                     cbSelect.isChecked = selectedUris.contains(item.toString())
                 }
diff --git a/app/src/main/java/io/legado/app/utils/ConvertUtils.kt b/app/src/main/java/io/legado/app/utils/ConvertExtensions.kt
similarity index 73%
rename from app/src/main/java/io/legado/app/utils/ConvertUtils.kt
rename to app/src/main/java/io/legado/app/utils/ConvertExtensions.kt
index 4609a3711..9a7e63722 100644
--- a/app/src/main/java/io/legado/app/utils/ConvertUtils.kt
+++ b/app/src/main/java/io/legado/app/utils/ConvertExtensions.kt
@@ -9,6 +9,8 @@ import java.io.BufferedReader
 import java.io.InputStream
 import java.io.InputStreamReader
 import java.text.DecimalFormat
+import kotlin.math.log10
+import kotlin.math.pow
 
 /**
  * 数据类型转换、单位转换
@@ -80,15 +82,13 @@ object ConvertUtils {
         return toDrawable(toBitmap(bytes))
     }
 
-    fun toFileSizeString(fileSize: Long): String {
-        val df = DecimalFormat("0.00")
-        val fileSizeString: String = when {
-            fileSize < KB -> fileSize.toString() + "B"
-            fileSize < MB -> df.format(fileSize.toDouble() / KB) + "K"
-            fileSize < GB -> df.format(fileSize.toDouble() / MB) + "M"
-            else -> df.format(fileSize.toDouble() / GB) + "G"
-        }
-        return fileSizeString
+    fun formatFileSize(length: Long): String {
+        if (length <= 0) return "0"
+        val units = arrayOf("b", "kb", "M", "G", "T")
+        //计算单位的，原理是利用lg,公式是 lg(1024^n) = nlg(1024)，最后 nlg(1024)/lg(1024) = n。
+        val digitGroups = (log10(length.toDouble()) / log10(1024.0)).toInt()
+        //计算原理是，size/单位值。单位值指的是:比如说b = 1024,KB = 1024^2
+        return DecimalFormat("#,##0.##").format(length / 1024.0.pow(digitGroups.toDouble())) + " " + units[digitGroups]
     }
 
     @JvmOverloads
@@ -110,4 +110,21 @@ object ConvertUtils {
         return sb.toString()
     }
 
-}
\ No newline at end of file
+}
+
+val Int.dp: Int
+    get() = android.util.TypedValue.applyDimension(
+        android.util.TypedValue.COMPLEX_UNIT_DIP,
+        this.toFloat(),
+        Resources.getSystem().displayMetrics
+    ).toInt()
+
+val Int.sp: Int
+    get() = android.util.TypedValue.applyDimension(
+        android.util.TypedValue.COMPLEX_UNIT_SP,
+        this.toFloat(),
+        Resources.getSystem().displayMetrics
+    ).toInt()
+
+val Int.hexString: String
+    get() = Integer.toHexString(this)
\ No newline at end of file
diff --git a/app/src/main/java/io/legado/app/utils/FileUtils.kt b/app/src/main/java/io/legado/app/utils/FileUtils.kt
index b654fd158..288e6da50 100644
--- a/app/src/main/java/io/legado/app/utils/FileUtils.kt
+++ b/app/src/main/java/io/legado/app/utils/FileUtils.kt
@@ -622,7 +622,7 @@ object FileUtils {
      */
     fun getSize(path: String): String {
         val fileSize = getLength(path)
-        return ConvertUtils.toFileSizeString(fileSize)
+        return ConvertUtils.formatFileSize(fileSize)
     }
 
     /**
diff --git a/app/src/main/java/io/legado/app/utils/IntExtensions.kt b/app/src/main/java/io/legado/app/utils/IntExtensions.kt
deleted file mode 100644
index dc03d0258..000000000
--- a/app/src/main/java/io/legado/app/utils/IntExtensions.kt
+++ /dev/null
@@ -1,20 +0,0 @@
-package io.legado.app.utils
-
-import android.content.res.Resources
-
-val Int.dp: Int
-    get() = android.util.TypedValue.applyDimension(
-        android.util.TypedValue.COMPLEX_UNIT_DIP,
-        this.toFloat(),
-        Resources.getSystem().displayMetrics
-    ).toInt()
-
-val Int.sp: Int
-    get() = android.util.TypedValue.applyDimension(
-        android.util.TypedValue.COMPLEX_UNIT_SP,
-        this.toFloat(),
-        Resources.getSystem().displayMetrics
-    ).toInt()
-
-val Int.hexString: String
-    get() = Integer.toHexString(this)
\ No newline at end of file
diff --git a/app/src/main/java/io/legado/app/utils/StringUtils.kt b/app/src/main/java/io/legado/app/utils/StringUtils.kt
index 6d9d49eca..43440fa86 100644
--- a/app/src/main/java/io/legado/app/utils/StringUtils.kt
+++ b/app/src/main/java/io/legado/app/utils/StringUtils.kt
@@ -9,8 +9,6 @@ import java.util.*
 import java.util.regex.Matcher
 import java.util.regex.Pattern
 import kotlin.math.abs
-import kotlin.math.log10
-import kotlin.math.pow
 
 @Suppress("unused", "MemberVisibilityCanBePrivate")
 object StringUtils {
@@ -42,17 +40,6 @@ object StringUtils {
             return map
         }
 
-    /**
-     * 将时间转换成日期
-     */
-    fun dateConvert(time: Long, pattern: String): String {
-        val date = Date(time)
-
-        @SuppressLint("SimpleDateFormat")
-        val format = SimpleDateFormat(pattern)
-        return format.format(date)
-    }
-
     /**
      * 将日期转换成昨天、今天、明天
      */
@@ -101,20 +88,6 @@ object StringUtils {
         return ""
     }
 
-    /**
-     * 单位转换
-     */
-    fun toSize(length: Long): String {
-        if (length <= 0) return "0"
-        val units = arrayOf("b", "kb", "M", "G", "T")
-        //计算单位的，原理是利用lg,公式是 lg(1024^n) = nlg(1024)，最后 nlg(1024)/lg(1024) = n。
-        val digitGroups =
-            (log10(length.toDouble()) / log10(1024.0)).toInt()
-        //计算原理是，size/单位值。单位值指的是:比如说b = 1024,KB = 1024^2
-        return DecimalFormat("#,##0.##")
-            .format(length / 1024.0.pow(digitGroups.toDouble())) + " " + units[digitGroups]
-    }
-
     /**
      * 首字母大写
      */