diff --git a/app/build.gradle b/app/build.gradle
index 368ed23..472a02c 100644
--- a/app/build.gradle
+++ b/app/build.gradle
@@ -12,8 +12,8 @@ android {
         applicationId "top.fumiama.base16384"
         minSdkVersion 23
         targetSdkVersion 30
-        versionCode 6
-        versionName '1.2'
+        versionCode 7
+        versionName '1.3'
         resConfigs "zh", "en"
 
         testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
diff --git a/app/src/main/java/top/fumiama/base16384/MainActivity.kt b/app/src/main/java/top/fumiama/base16384/MainActivity.kt
index c1afced..57abd56 100644
--- a/app/src/main/java/top/fumiama/base16384/MainActivity.kt
+++ b/app/src/main/java/top/fumiama/base16384/MainActivity.kt
@@ -13,23 +13,36 @@ import android.net.Uri
 import android.os.Build
 import android.os.Bundle
 import android.view.View
+import android.widget.ArrayAdapter
+import android.widget.ListAdapter
 import android.widget.Toast
 import androidx.core.app.ActivityCompat
 import androidx.core.content.ContextCompat
 import com.google.android.material.textfield.TextInputEditText
 import kotlinx.android.synthetic.main.activity_main.*
+import top.fumiama.base16384.tools.PropertiesTools
 import java.io.File
 import java.io.FileInputStream
+import java.nio.charset.Charset
 
 class MainActivity : Activity() {
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
         val cm = getSystemService(Context.CLIPBOARD_SERVICE) as ClipboardManager
+        val pCharsets = PropertiesTools(File(filesDir, "charsets.prop"))
         sv.viewTreeObserver.addOnGlobalLayoutListener { setTitleVisibility() }
-        fab.setOnClickListener { if(checkReadPermission()) pickFile() }
-        ben.setOnClickListener { clickButton(true, cm) }
-        bde.setOnClickListener { clickButton(false, cm) }
+        fab.setOnClickListener { pickFile() }
+        ben.setOnClickListener { clickButton(true, cm, pCharsets) }
+        bde.setOnClickListener { clickButton(false, cm, pCharsets) }
+        ben.setOnLongClickListener {
+            callCharsetSelectList(true, pCharsets)
+            false
+        }
+        bde.setOnLongClickListener {
+            callCharsetSelectList(false, pCharsets)
+            false
+        }
         tti.setOnLongClickListener {
             AlertDialog.Builder(this).setTitle(R.string.info).setMessage(R.string.info_content).setIcon(R.mipmap.ic_launcher).show()
             true
@@ -46,19 +59,6 @@ class MainActivity : Activity() {
         }
     }
 
-    override fun onRequestPermissionsResult(
-        requestCode: Int,
-        permissions: Array<String?>,
-        grantResults: IntArray
-    ) {
-        when (requestCode) {
-            1 -> {
-                if (grantResults.isNotEmpty() && grantResults[0] == PackageManager.PERMISSION_GRANTED) pickFile()
-                else Toast.makeText(this, R.string.permissionDenied, Toast.LENGTH_SHORT).show()
-            }
-        }
-    }
-
     private fun doFromFile(uri: Uri){
         val inputFile = generateCacheFile("input")
         val outputFile = generateCacheFile("output")
@@ -112,20 +112,6 @@ class MainActivity : Activity() {
         startActivityForResult(intent, 2)
     }
 
-    private fun checkReadPermission(): Boolean {
-        return if (Build.VERSION.SDK_INT < Build.VERSION_CODES.N && ContextCompat.checkSelfPermission(
-                this,
-                Manifest.permission.READ_EXTERNAL_STORAGE
-            ) != PackageManager.PERMISSION_GRANTED) {
-            ActivityCompat.requestPermissions(
-                this,
-                arrayOf(Manifest.permission.READ_EXTERNAL_STORAGE),
-                1
-            )
-            false
-        } else true
-    }
-
     private fun pickFile() {
         val i = Intent(Intent.ACTION_GET_CONTENT)
         i.type = "*/*"
@@ -148,17 +134,17 @@ class MainActivity : Activity() {
         }
     }
 
-    private fun clickButton(isEncode: Boolean, cm:ClipboardManager){
+    private fun clickButton(isEncode: Boolean, cm:ClipboardManager, pc: PropertiesTools){
         val tin = if(isEncode)ten else tde
         val tou = if(isEncode)tde else ten
         tin.text?.let {
             if(it.isNotEmpty()){
                 val inputFile = generateCacheFile("input")
                 val outputFile = generateCacheFile("output")
-                inputFile.writeText(it.toString(), Charsets.UTF_16BE)
+                inputFile.writeText(it.toString(), getCharset(getCustomCharsetPosition(isEncode, pc)))
                 if(isEncode) encode(inputFile.absolutePath, outputFile.absolutePath)
                 else decode(inputFile.absolutePath, outputFile.absolutePath)
-                tou.setText(outputFile.readText(Charsets.UTF_16BE))
+                tou.setText(outputFile.readText(getCharset(getCustomCharsetPosition(!isEncode, pc))))
                 copyText(tou, cm)
             }
         }
@@ -171,6 +157,41 @@ class MainActivity : Activity() {
         tti.visibility = if(h > r.bottom) View.GONE else View.VISIBLE
     }
 
+    private fun callCharsetSelectList(isEncode: Boolean, pc: PropertiesTools){
+        val charsetsArr = resources.getStringArray(R.array.charsets)
+        AlertDialog.Builder(this)
+                .setTitle(R.string.select_charset)
+                .setIcon(R.mipmap.ic_launcher)
+                .setSingleChoiceItems(ArrayAdapter(this, android.R.layout.simple_list_item_single_choice, charsetsArr), getCustomCharsetPosition(isEncode, pc)){ d, p ->
+                    setCustomCharsetPosition(p, isEncode, pc)
+                    d.cancel()
+                }.show()
+    }
+
+    private fun getCustomCharsetPosition(isEncode: Boolean, pc: PropertiesTools): Int{
+        val cs = if(isEncode) pc["encode"] else pc["decode"]
+        return if(cs == "null"){
+            if(isEncode) 8 else 3
+        }else cs.toInt()
+    }
+
+    private fun setCustomCharsetPosition(p: Int, isEncode: Boolean, pc: PropertiesTools){
+        pc[if(isEncode) "encode" else "decode"] = p.toString()
+    }
+
+    private fun getCharset(p: Int) = when (p) {
+        0 -> Charsets.ISO_8859_1
+        1 -> Charsets.US_ASCII
+        2 -> Charsets.UTF_16
+        3 -> Charsets.UTF_16BE
+        4 -> Charsets.UTF_16LE
+        5 -> Charsets.UTF_32
+        6 -> Charsets.UTF_32BE
+        7 -> Charsets.UTF_32LE
+        8 -> Charsets.UTF_8
+        else -> Charset.defaultCharset()
+    }
+
     /**
      * A native method that is implemented by the 'native-lib' native library,
      * which is packaged with this application.
diff --git a/app/src/main/java/top/fumiama/base16384/tools/PropertiesTools.kt b/app/src/main/java/top/fumiama/base16384/tools/PropertiesTools.kt
new file mode 100644
index 0000000..606d80e
--- /dev/null
+++ b/app/src/main/java/top/fumiama/base16384/tools/PropertiesTools.kt
@@ -0,0 +1,53 @@
+package top.fumiama.base16384.tools
+//PropertiesTools.kt
+//created by fumiama 20200724
+import android.util.Log
+import java.io.File
+import java.io.InputStream
+import java.util.*
+
+class PropertiesTools(private val f: File):Properties() {
+    private val propfile:File
+    get() {
+        if(!f.exists()) {
+            if(f.parentFile?.exists() != true) f.parentFile?.mkdirs()
+            if(f.parentFile?.canWrite() != true) f.parentFile?.setWritable(true)
+            createNew(f)
+        }else if(f.isDirectory) {
+            if(f.parentFile?.canWrite() != true) f.parentFile?.setWritable(true)
+            f.delete()
+            createNew(f)
+        }
+        if(f.parentFile?.canWrite() != true) f.parentFile?.setWritable(true)
+        if(f.parentFile?.canRead() != true) f.parentFile?.setReadable(true)
+        return f
+    }
+    private fun createNew(f: File){
+        f.createNewFile()
+        val o = f.outputStream()
+        this.storeToXML(o, "store")
+        Log.d("MyPT", "Generate new prop.")
+        o.close()
+    }
+    private fun loadFromXml(`in`: InputStream?): PropertiesTools {
+        this.loadFromXML(`in`)
+        return this
+    }
+    private fun setProp(key: String?, value: String?): PropertiesTools {
+        this.setProperty(key, value)
+        return this
+    }
+    operator fun get(key: String): String{
+        val i = propfile.inputStream()
+        val re = this.loadFromXml(i).getProperty(key)?:"null"
+        Log.d("MyPT", "Get $key = $re")
+        i.close()
+        return re
+    }
+    operator fun set(key: String, value: String){
+        val o = propfile.outputStream()
+        this.setProp(key, value).storeToXML(o, "store")
+        Log.d("MyPT", "Set $key = $value")
+        o.close()
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/res/values-zh/strings.xml b/app/src/main/res/values-zh/strings.xml
index de86fd9..38799f1 100644
--- a/app/src/main/res/values-zh/strings.xml
+++ b/app/src/main/res/values-zh/strings.xml
@@ -16,4 +16,5 @@
     <string name="info">关于</string>
     <string name="info_content">作者：源文雨。感谢咲桜动漫社成员的支持。</string>
     <string name="copied">已复制</string>
+    <string name="select_charset">选择字符集</string>
 </resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/charsets.xml b/app/src/main/res/values/charsets.xml
new file mode 100644
index 0000000..bdc7e6c
--- /dev/null
+++ b/app/src/main/res/values/charsets.xml
@@ -0,0 +1,14 @@
+<?xml version="1.0" encoding="utf-8"?>
+<resources>
+    <string-array name="charsets">
+        <item>ISO_8859_1</item>
+        <item>US_ASCII</item>
+        <item>UTF_16</item>
+        <item>UTF_16BE</item>
+        <item>UTF_16LE</item>
+        <item>UTF_32</item>
+        <item>UTF_32BE</item>
+        <item>UTF_32LE</item>
+        <item>UTF_8</item>
+    </string-array>
+</resources>
\ No newline at end of file
diff --git a/app/src/main/res/values/strings.xml b/app/src/main/res/values/strings.xml
index 751d590..d0526f9 100644
--- a/app/src/main/res/values/strings.xml
+++ b/app/src/main/res/values/strings.xml
@@ -13,6 +13,7 @@
     <string name="decode_succeed">Decode Succeed</string>
     <string name="encode_succeed">Encode Succeed</string>
     <string name="info">Info</string>
-    <string name="info_content">Author: Fumiama, with precious supports of the members in Sakura Anime Club.</string>
+    <string name="info_content">Author: Fumiama, with precious supports from the members in Sakura Anime Club.</string>
     <string name="copied">Copied Text</string>
+    <string name="select_charset">Select Charset</string>
 </resources>
\ No newline at end of file