diff --git a/android/app/build.gradle b/android/app/build.gradle
index 4f4416a..8a27916 100644
--- a/android/app/build.gradle
+++ b/android/app/build.gradle
@@ -87,4 +87,6 @@ dependencies {
     implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
     implementation 'com.github.DylanCaiCoding:MMKV-KTX:1.2.16'
     implementation 'androidx.documentfile:documentfile:1.0.1'
+    implementation "org.greenrobot:eventbus:3.3.1"
+    implementation "com.anggrayudi:storage:1.5.5"
 }
diff --git a/android/app/src/main/kotlin/com/lifegpc/ehf/MainActivity.kt b/android/app/src/main/kotlin/com/lifegpc/ehf/MainActivity.kt
index cd90c0c..d98ff23 100644
--- a/android/app/src/main/kotlin/com/lifegpc/ehf/MainActivity.kt
+++ b/android/app/src/main/kotlin/com/lifegpc/ehf/MainActivity.kt
@@ -2,124 +2,41 @@ package com.lifegpc.ehf
 
 import android.app.Activity
 import android.content.Intent
-import android.net.Uri
-import androidx.documentfile.provider.DocumentFile
-import com.lifegpc.ehf.annotation.ChannelMethod
-import com.lifegpc.ehf.data.mmkv.SAFSettings
-import com.lifegpc.ehf.util.ClipboardUtils
-import com.lifegpc.ehf.util.MethodChannelUtils
+import com.lifegpc.ehf.eventbus.SAFAuthEvent
+import com.lifegpc.ehf.platform.ClipboardPlugin
+import com.lifegpc.ehf.platform.MethodChannelUtils
+import com.lifegpc.ehf.platform.SAFPlugin
 import io.flutter.embedding.android.FlutterActivity
 import io.flutter.embedding.engine.FlutterEngine
-import io.flutter.plugin.common.MethodChannel
+import org.greenrobot.eventbus.EventBus
 
 class MainActivity : FlutterActivity() {
-    private val safAuthorizationCode = 0x10086
-    private var safAuthorizationResult: MethodChannel.Result? = null
-    private var afterAuthSuccess: (() -> Unit)? = null
 
     override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
         super.configureFlutterEngine(flutterEngine)
         MethodChannelUtils.registerMethodChannel(
             "lifegpc.eh_downloader_flutter/saf",
             flutterEngine,
-            this
+            SAFPlugin(this)
         )
         MethodChannelUtils.registerMethodChannel(
             "lifegpc.eh_downloader_flutter/clipboard",
             flutterEngine,
-            ClipboardUtils
+            ClipboardPlugin
         )
     }
 
-    @ChannelMethod(responseManually = true)
-    private fun saveFile(
-        channelResult: MethodChannel.Result,
-        filename: String,
-        dir: String,
-        mimeType: String,
-        content: ByteArray
-    ) {
-        this.safAuthorizationResult = channelResult
-        if (!checkSafPermission()) {
-            authSAF(channelResult) {
-                doWriteFile(filename, dir, mimeType, content)
-                channelResult.success(null)
-            }
-        } else {
-            doWriteFile(filename, dir, mimeType, content)
-            channelResult.success(null)
-        }
-    }
-
-    private fun doWriteFile(filename: String, dir: String, mimeType: String, content: ByteArray) {
-        var documentDir = DocumentFile.fromTreeUri(this, Uri.parse(SAFSettings.authorizedUri))!!
-        val pathPart = dir.split('/', '\\')
-        pathPart.forEach {
-            if (it.isNotEmpty()) {
-                documentDir = documentDir.createDirectory(it)!!
-            }
-        }
-
-        val filenameWithoutExtension = if (filename.indexOf('.') != -1) {
-            filename.substring(0, filename.lastIndexOf('.'))
-        } else {
-            filename
-        }
-        val file = documentDir.createFile(mimeType, filenameWithoutExtension)!!
-        val uri = file.uri
-        contentResolver.openOutputStream(uri)!!.use {
-            it.write(content)
-        }
-    }
-
-    private fun authSAF(result: MethodChannel.Result, onSuccess: (() -> Unit)? = null) {
-        val intent = Intent(Intent.ACTION_OPEN_DOCUMENT_TREE)
-        startActivityForResult(intent, safAuthorizationCode)
-        safAuthorizationResult = result
-        this.afterAuthSuccess = onSuccess
-    }
-
-    private fun onSafAuthSuccess(data: Intent) {
-        // 保存权限
-        val resultData = data.data!!
-        val takeFlags =
-            (Intent.FLAG_GRANT_READ_URI_PERMISSION or Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
-        contentResolver.takePersistableUriPermission(resultData, takeFlags)
-        SAFSettings.authorizedUri = resultData.toString()
-    }
-
-    private fun checkSafPermission(): Boolean {
-        val dir = SAFSettings.authorizedUri
-        if (dir.isBlank()) return false
-
-        val uri = Uri.parse(dir)
-
-        return try {
-            val flags =
-                Intent.FLAG_GRANT_READ_URI_PERMISSION or Intent.FLAG_GRANT_WRITE_URI_PERMISSION
-            contentResolver.takePersistableUriPermission(uri, flags)
-            DocumentFile.fromTreeUri(this, uri)
-            true
-        } catch (e: Exception) {
-            e.printStackTrace()
-            false
-        }
-    }
-
     override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
         super.onActivityResult(requestCode, resultCode, data)
         when (requestCode) {
-            safAuthorizationCode -> {
+            SAFPlugin.safAuthorizationCode -> {
                 if (resultCode == Activity.RESULT_OK) {
                     // 授权成功
-                    onSafAuthSuccess(data!!)
-                    afterAuthSuccess?.invoke()
+                    EventBus.getDefault().post(SAFAuthEvent(true, data!!))
                 } else {
                     // 授权失败
-                    safAuthorizationResult?.error("Permission denied", null, null)
-                    safAuthorizationResult = null
+                    EventBus.getDefault().post(SAFAuthEvent(false, null))
                 }
-                afterAuthSuccess = null
             }
         }
     }
diff --git a/android/app/src/main/kotlin/com/lifegpc/ehf/eventbus/SAFAuthEvent.kt b/android/app/src/main/kotlin/com/lifegpc/ehf/eventbus/SAFAuthEvent.kt
new file mode 100644
index 0000000..6343598
--- /dev/null
+++ b/android/app/src/main/kotlin/com/lifegpc/ehf/eventbus/SAFAuthEvent.kt
@@ -0,0 +1,8 @@
+package com.lifegpc.ehf.eventbus
+
+import android.content.Intent
+
+data class SAFAuthEvent(
+    val success: Boolean = true,
+    val data: Intent?,
+)
\ No newline at end of file
diff --git a/android/app/src/main/kotlin/com/lifegpc/ehf/util/ClipboardUtils.kt b/android/app/src/main/kotlin/com/lifegpc/ehf/platform/ClipboardPlugin.kt
similarity index 97%
rename from android/app/src/main/kotlin/com/lifegpc/ehf/util/ClipboardUtils.kt
rename to android/app/src/main/kotlin/com/lifegpc/ehf/platform/ClipboardPlugin.kt
index 04b4860..b972e28 100644
--- a/android/app/src/main/kotlin/com/lifegpc/ehf/util/ClipboardUtils.kt
+++ b/android/app/src/main/kotlin/com/lifegpc/ehf/platform/ClipboardPlugin.kt
@@ -1,4 +1,4 @@
-package com.lifegpc.ehf.util
+package com.lifegpc.ehf.platform
 
 import android.content.ClipData
 import android.content.ClipboardManager
@@ -12,7 +12,7 @@ import com.lifegpc.ehf.annotation.ChannelMethod
 import java.io.File
 import java.util.UUID
 
-object ClipboardUtils {
+object ClipboardPlugin {
     private const val AUTHORITY = "com.lifegpc.ehf.ClipboardImageProvider"
 
     @ChannelMethod
diff --git a/android/app/src/main/kotlin/com/lifegpc/ehf/util/MethodChannelUtils.kt b/android/app/src/main/kotlin/com/lifegpc/ehf/platform/MethodChannelUtils.kt
similarity index 99%
rename from android/app/src/main/kotlin/com/lifegpc/ehf/util/MethodChannelUtils.kt
rename to android/app/src/main/kotlin/com/lifegpc/ehf/platform/MethodChannelUtils.kt
index 6758ae8..af46479 100644
--- a/android/app/src/main/kotlin/com/lifegpc/ehf/util/MethodChannelUtils.kt
+++ b/android/app/src/main/kotlin/com/lifegpc/ehf/platform/MethodChannelUtils.kt
@@ -1,4 +1,4 @@
-package com.lifegpc.ehf.util
+package com.lifegpc.ehf.platform
 
 import android.util.Log
 import com.lifegpc.ehf.annotation.ChannelMethod
diff --git a/android/app/src/main/kotlin/com/lifegpc/ehf/platform/SAFPlugin.kt b/android/app/src/main/kotlin/com/lifegpc/ehf/platform/SAFPlugin.kt
new file mode 100644
index 0000000..946b3a0
--- /dev/null
+++ b/android/app/src/main/kotlin/com/lifegpc/ehf/platform/SAFPlugin.kt
@@ -0,0 +1,190 @@
+package com.lifegpc.ehf.platform
+
+import android.content.Intent
+import android.net.Uri
+import androidx.documentfile.provider.DocumentFile
+import com.anggrayudi.storage.file.makeFile
+import com.anggrayudi.storage.file.openOutputStream
+import com.lifegpc.ehf.MainActivity
+import com.lifegpc.ehf.annotation.ChannelMethod
+import com.lifegpc.ehf.data.mmkv.SAFSettings
+import com.lifegpc.ehf.eventbus.SAFAuthEvent
+import io.flutter.plugin.common.MethodChannel
+import org.greenrobot.eventbus.EventBus
+import org.greenrobot.eventbus.Subscribe
+
+class SAFPlugin(private val activity: MainActivity) {
+    private var safAuthorizationResult: MethodChannel.Result? = null
+    private val fdMap = mutableMapOf<Int, DocumentFile>()
+    private var onSAFAuthSuccess: (() -> Unit)? = null
+    private var onSAFAuthFailed: (() -> Unit)? = null
+
+    companion object {
+        const val safAuthorizationCode = 0x10086
+    }
+
+    init {
+        EventBus.getDefault().register(this)
+    }
+
+    @Subscribe
+    @Suppress("unused")
+    fun onSAFAuthResult(event: SAFAuthEvent) {
+        if (!event.success) {
+            onSAFAuthFailed?.invoke()
+            onSAFAuthFailed = null
+            return
+        }
+
+        val data = event.data!!
+        val authUri = data.data!!
+        saveSAFPermission(authUri)
+        onSAFAuthSuccess?.invoke()
+        onSAFAuthSuccess = null
+    }
+
+    @ChannelMethod(responseManually = true)
+    @Suppress("unused")
+    private fun saveFile(
+        channelResult: MethodChannel.Result,
+        filename: String,
+        dir: String,
+        mimeType: String,
+        content: ByteArray
+    ) {
+        this.safAuthorizationResult = channelResult
+        if (!checkSafPermission()) {
+            onSAFAuthSuccess = {
+                doWriteFile(filename, dir, mimeType, content)
+                channelResult.success(null)
+            }
+            onSAFAuthFailed = {
+                channelResult.error("Permission denied", null, null)
+            }
+            authSAF()
+        } else {
+            doWriteFile(filename, dir, mimeType, content)
+            channelResult.success(null)
+        }
+    }
+
+    @ChannelMethod(responseManually = true)
+    @Suppress("unused")
+    private fun openFile(
+        channelResult: MethodChannel.Result,
+        filenameWithoutExtension: String,
+        dir: String,
+        mimeType: String,
+    ) {
+        if (!checkSafPermission()) {
+            onSAFAuthSuccess = {
+                channelResult.success(doOpenFile(filenameWithoutExtension, mimeType, dir))
+            }
+            onSAFAuthFailed = {
+                channelResult.error("Permission denied", null, null)
+            }
+            authSAF()
+        } else {
+            channelResult.success(doOpenFile(filenameWithoutExtension, mimeType, dir))
+        }
+    }
+
+    private fun doOpenFile(filenameWithoutExtension: String, mimeType: String, dir: String): Int {
+        var documentFile =
+            DocumentFile.fromTreeUri(activity, Uri.parse(SAFSettings.authorizedUri))!!
+        documentFile = createFileRecursively(documentFile, dir)
+
+        val f = documentFile.makeFile(activity, filenameWithoutExtension, mimeType)!!
+
+        val id = f.hashCode()
+        fdMap[id] = f
+        return id
+    }
+
+    /**
+     * 写入文件
+     * @param id Int
+     * @param bytes ByteArray
+     * @return Int 写入的字节数
+     */
+    @ChannelMethod
+    @Suppress("unused")
+    private fun writeFile(id: Int, bytes: ByteArray, append: Boolean): Int {
+        val f = fdMap[id]!!
+        f.openOutputStream(activity, append)!!.use {
+            it.write(bytes)
+        }
+        return bytes.size
+    }
+
+    @ChannelMethod
+    @Suppress("unused")
+    private fun closeFile(id: Int) {
+        fdMap.remove(id)
+    }
+
+    private fun createFileRecursively(base: DocumentFile, dir: String): DocumentFile {
+        var file = base
+        val pathPart = dir.split('/', '\\')
+        pathPart.forEach {
+            if (it.isNotEmpty()) {
+                file = file.createDirectory(it)!!
+            }
+        }
+        return file
+    }
+
+    /**
+     * 写入文件
+     * @param filename String
+     * @param dir String
+     * @param mimeType String
+     * @param content ByteArray
+     */
+    private fun doWriteFile(filename: String, dir: String, mimeType: String, content: ByteArray) {
+        var documentDir = DocumentFile.fromTreeUri(activity, Uri.parse(SAFSettings.authorizedUri))!!
+        documentDir = createFileRecursively(documentDir, dir)
+
+        val filenameWithoutExtension = if (filename.indexOf('.') != -1) {
+            filename.substring(0, filename.lastIndexOf('.'))
+        } else {
+            filename
+        }
+        val file = documentDir.createFile(mimeType, filenameWithoutExtension)!!
+        val uri = file.uri
+        activity.contentResolver.openOutputStream(uri)!!.use {
+            it.write(content)
+        }
+    }
+
+    private fun authSAF() {
+        val intent = Intent(Intent.ACTION_OPEN_DOCUMENT_TREE)
+        activity.startActivityForResult(intent, safAuthorizationCode)
+    }
+
+    // 保存权限
+    private fun saveSAFPermission(uri: Uri) {
+        val takeFlags =
+            (Intent.FLAG_GRANT_READ_URI_PERMISSION or Intent.FLAG_GRANT_WRITE_URI_PERMISSION)
+        activity.contentResolver.takePersistableUriPermission(uri, takeFlags)
+        SAFSettings.authorizedUri = uri.toString()
+    }
+
+    private fun checkSafPermission(): Boolean {
+        val dir = SAFSettings.authorizedUri
+        if (dir.isBlank()) return false
+
+        val uri = Uri.parse(dir)
+
+        return try {
+            val flags =
+                Intent.FLAG_GRANT_READ_URI_PERMISSION or Intent.FLAG_GRANT_WRITE_URI_PERMISSION
+            activity.contentResolver.takePersistableUriPermission(uri, flags)
+            DocumentFile.fromTreeUri(activity, uri)
+            true
+        } catch (e: Exception) {
+            e.printStackTrace()
+            false
+        }
+    }
+}
\ No newline at end of file
diff --git a/lib/platform/path.dart b/lib/platform/path.dart
index e8a8bcb..4baed45 100644
--- a/lib/platform/path.dart
+++ b/lib/platform/path.dart
@@ -1,7 +1,9 @@
 import 'dart:async';
+
 import 'package:flutter/foundation.dart';
 import 'package:flutter/services.dart';
 import 'package:logging/logging.dart';
+
 import '../utils.dart';
 import 'save_file.dart';
 
@@ -50,11 +52,19 @@ class Path {
 
 class SAFFile {
   SAFFile(this._fd);
+
   final int _fd;
   bool _disposed = false;
-  Future<int> write(Uint8List data) async {
+
+  /// 写入文件，返回此次写入的字节数
+  ///
+  /// [data] 要写入文件的数据
+  ///
+  /// [append] 如果为 true 则追加写入，如果为 false 则清空原始文件内容，重新写入，默认为 true
+  Future<int> write(Uint8List data, {bool append = true}) async {
     if (_disposed) throw Exception("File already closed");
-    return await Path._safChannel.invokeMethod("writeFile", [_fd, data]);
+    return await Path._safChannel
+        .invokeMethod("writeFile", [_fd, data, append]);
   }
 
   Future<void> dispose() async {
diff --git a/pubspec.lock b/pubspec.lock
index fc76759..718aae3 100644
--- a/pubspec.lock
+++ b/pubspec.lock
@@ -21,10 +21,10 @@ packages:
     dependency: transitive
     description:
       name: archive
-      sha256: "49b1fad315e57ab0bbc15bcbb874e83116a1d78f77ebd500a4af6c9407d6b28e"
+      sha256: e0902a06f0e00414e4e3438a084580161279f137aeb862274710f29ec10cf01e
       url: "https://pub.dev"
     source: hosted
-    version: "3.3.8"
+    version: "3.3.9"
   args:
     dependency: transitive
     description:
@@ -77,10 +77,10 @@ packages:
     dependency: transitive
     description:
       name: build_resolvers
-      sha256: a7417cc44d9edb3f2c8760000270c99dba8c72ff66d0146772b8326565780745
+      sha256: d912852cce27c9e80a93603db721c267716894462e7033165178b91138587972
       url: "https://pub.dev"
     source: hosted
-    version: "2.3.1"
+    version: "2.3.2"
   build_runner:
     dependency: "direct dev"
     description:
@@ -190,26 +190,26 @@ packages:
     dependency: "direct main"
     description:
       name: cryptography
-      sha256: df156c5109286340817d21fa7b62f9140f17915077127dd70f8bd7a2a0997a35
+      sha256: "11d083541666d80bba21190d35ff70b2497c81e064e82d1b8a07d801f7c7e282"
       url: "https://pub.dev"
     source: hosted
-    version: "2.5.0"
+    version: "2.6.0"
   cryptography_flutter:
     dependency: "direct main"
     description:
       name: cryptography_flutter
-      sha256: a66ce021e0b600688c2d51b0594cb156ee677ce9bfbc981b62219ad577dd302e
+      sha256: "423ac095bbc4650fe6c07c64632ddc5dda1d4851241367efa0f26ca24b0ce480"
       url: "https://pub.dev"
     source: hosted
-    version: "2.3.0"
+    version: "2.3.1"
   dart_style:
     dependency: transitive
     description:
       name: dart_style
-      sha256: "1efa911ca7086affd35f463ca2fc1799584fb6aa89883cf0af8e3664d6a02d55"
+      sha256: abd7625e16f51f554ea244d090292945ec4d4be7bfbaf2ec8cccea568919d334
       url: "https://pub.dev"
     source: hosted
-    version: "2.3.2"
+    version: "2.3.3"
   device_info_plus:
     dependency: transitive
     description:
@@ -980,5 +980,5 @@ packages:
     source: hosted
     version: "3.1.2"
 sdks:
-  dart: ">=3.1.0-185.0.dev <4.0.0"
-  flutter: ">=3.7.0"
+  dart: ">=3.1.0 <4.0.0"
+  flutter: ">=3.13.0"