diff --git a/app/src/main/java/io/legado/app/lib/webdav/README.md b/app/src/main/java/io/legado/app/lib/webdav/README.md
new file mode 100644
index 000000000..f6ac57a9d
--- /dev/null
+++ b/app/src/main/java/io/legado/app/lib/webdav/README.md
@@ -0,0 +1 @@
+## 用于网络备份的WebDav
\ No newline at end of file
diff --git a/app/src/main/java/io/legado/app/lib/webdav/WebDav.kt b/app/src/main/java/io/legado/app/lib/webdav/WebDav.kt
new file mode 100644
index 000000000..a3f695171
--- /dev/null
+++ b/app/src/main/java/io/legado/app/lib/webdav/WebDav.kt
@@ -0,0 +1,320 @@
+package io.legado.app.lib.webdav
+
+import io.legado.app.lib.webdav.http.Handler
+import io.legado.app.lib.webdav.http.HttpAuth
+import io.legado.app.lib.webdav.http.OkHttp
+
+import org.jsoup.Jsoup
+import org.jsoup.nodes.Document
+import org.jsoup.nodes.Element
+import org.jsoup.select.Elements
+
+import java.io.File
+import java.io.FileOutputStream
+import java.io.IOException
+import java.io.InputStream
+import java.io.UnsupportedEncodingException
+import java.lang.reflect.Field
+import java.net.MalformedURLException
+import java.net.URL
+import java.net.URLEncoder
+import java.util.ArrayList
+
+import okhttp3.Credentials
+import okhttp3.MediaType
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import okhttp3.RequestBody
+import okhttp3.Response
+
+class WebDav @Throws(MalformedURLException::class)
+constructor(url: String) {
+
+    private val url: URL
+    private var httpUrl: String? = null
+
+    var displayName: String? = null
+    var createTime: Long = 0
+    var lastModified: Long = 0
+    var size: Long = 0
+    var isDirectory = true
+    private var exists = false
+    var parent = ""
+    var urlName = ""
+        get() {
+            if (field.isEmpty()) {
+                this.urlName = (if (parent.isEmpty()) url.file else url.toString().replace(parent, "")).replace("/", "")
+            }
+            return field
+        }
+
+    private val okHttpClient: OkHttpClient
+
+    val path: String
+        get() = url.toString()
+
+    private val inputStream: InputStream?
+        get() {
+            val request = Request.Builder()
+                .url(getUrl()!!)
+
+            val auth = HttpAuth.auth
+
+            if (auth != null) {
+                request.header("Authorization", Credentials.basic(auth!!.user, auth!!.pass))
+            }
+
+            try {
+                val response = okHttpClient.newCall(request.build()).execute()
+                return response.body()!!.byteStream()
+            } catch (e: IOException) {
+                e.printStackTrace()
+            } catch (e: IllegalArgumentException) {
+                e.printStackTrace()
+            }
+
+            return null
+        }
+
+    val host: String
+        get() = url.host
+
+    init {
+        this.url = URL(null, url, Handler.HANDLER)
+        okHttpClient = OkHttp.instance.okHttpClient
+    }
+
+    fun getUrl(): String? {
+        if (httpUrl == null) {
+            val raw = url.toString().replace("davs://", "https://").replace("dav://", "http://")
+            try {
+                httpUrl = URLEncoder.encode(raw, "UTF-8")
+                    .replace("\\+".toRegex(), "%20")
+                    .replace("%3A".toRegex(), ":")
+                    .replace("%2F".toRegex(), "/")
+            } catch (e: UnsupportedEncodingException) {
+                e.printStackTrace()
+            }
+
+        }
+        return httpUrl
+    }
+
+    /**
+     * 填充文件信息。实例化WebDAVFile对象时，并没有将远程文件的信息填充到实例中。需要手动填充！
+     *
+     * @return 远程文件是否存在
+     */
+    @Throws(IOException::class)
+    fun indexFileInfo(): Boolean {
+        val response = propFindResponse(ArrayList())
+        var s = ""
+        try {
+            if (response == null || !response.isSuccessful) {
+                this.exists = false
+                return false
+            }
+            s = response.body()!!.string()
+        } catch (e: Exception) {
+            e.printStackTrace()
+        }
+
+
+        return false
+    }
+
+    /**
+     * 列出当前路径下的文件
+     *
+     * @param propsList 指定列出文件的哪些属性
+     * @return 文件列表
+     */
+    @Throws(IOException::class)
+    @JvmOverloads
+    fun listFiles(propsList: ArrayList<String> = ArrayList()): List<WebDav> {
+        val response = propFindResponse(propsList)
+        try {
+            assert(response != null)
+            if (response.isSuccessful) {
+                return parseDir(response.body()!!.string())
+            }
+        } catch (e: Exception) {
+            e.printStackTrace()
+        }
+
+        return ArrayList()
+    }
+
+    @Throws(IOException::class)
+    private fun propFindResponse(propsList: ArrayList<String>, depth: Int = 1): Response {
+        val requestProps = StringBuilder()
+        for (p in propsList) {
+            requestProps.append("<a:").append(p).append("/>\n")
+        }
+        val requestPropsStr: String
+        if (requestProps.toString().isEmpty()) {
+            requestPropsStr = DIR.replace("%s", "")
+        } else {
+            requestPropsStr = String.format(DIR, requestProps.toString() + "\n")
+        }
+        val request = Request.Builder()
+            .url(getUrl()!!)
+            // 添加RequestBody对象，可以只返回的属性。如果设为null，则会返回全部属性
+            // 注意：尽量手动指定需要返回的属性。若返回全部属性，可能后由于Prop.java里没有该属性名，而崩溃。
+            .method("PROPFIND", RequestBody.create(MediaType.parse("text/plain"), requestPropsStr))
+
+        val auth = HttpAuth.auth
+        if (auth != null) {
+            request.header("Authorization", Credentials.basic(auth!!.user, auth!!.pass))
+        }
+        request.header("Depth", if (depth < 0) "infinity" else Integer.toString(depth))
+
+        return okHttpClient.newCall(request.build()).execute()
+    }
+
+    private fun parseDir(s: String): List<WebDav> {
+        val list = ArrayList<WebDav>()
+        val document = Jsoup.parse(s)
+        val elements = document.getElementsByTag("d:response")
+        val baseUrl = if (getUrl()!!.endsWith("/")) getUrl() else getUrl()!! + "/"
+        for (element in elements) {
+            val href = element.getElementsByTag("d:href")[0].text()
+            if (!href.endsWith("/")) {
+                val fileName = href.substring(href.lastIndexOf("/") + 1)
+                val webDavFile: WebDav
+                try {
+                    webDavFile = WebDav(baseUrl!! + fileName)
+                    webDavFile.displayName = fileName
+                    webDavFile.urlName = href
+                    list.add(webDavFile)
+                } catch (e: MalformedURLException) {
+                    e.printStackTrace()
+                }
+
+            }
+        }
+        return list
+    }
+
+    /**
+     * 根据自己的URL，在远程处创建对应的文件夹
+     *
+     * @return 是否创建成功
+     */
+    @Throws(IOException::class)
+    fun makeAsDir(): Boolean {
+        val request = Request.Builder()
+            .url(getUrl()!!)
+            .method("MKCOL", null)
+        return execRequest(request)
+    }
+
+    /**
+     * 下载到本地
+     *
+     * @param savedPath       本地的完整路径，包括最后的文件名
+     * @param replaceExisting 是否替换本地的同名文件
+     * @return 下载是否成功
+     */
+    fun download(savedPath: String, replaceExisting: Boolean): Boolean {
+        val file = File(savedPath)
+        if (file.exists()) {
+            if (replaceExisting) {
+                file.delete()
+            } else {
+                return false
+            }
+        }
+        val inputS = inputStream ?: return false
+        try {
+            file.createNewFile()
+            file.writeBytes(inputS.readBytes())
+            return true
+        } catch (e: Exception) {
+            e.printStackTrace()
+        }
+        return false
+    }
+
+    @Throws(IOException::class)
+    @JvmOverloads
+    fun upload(localPath: String, contentType: String? = null): Boolean {
+        val file = File(localPath)
+        if (!file.exists()) return false
+        val mediaType = if (contentType == null) null else MediaType.parse(contentType)
+        // 务必注意RequestBody不要嵌套，不然上传时内容可能会被追加多余的文件信息
+        val fileBody = RequestBody.create(mediaType, file)
+        val request = Request.Builder()
+            .url(getUrl()!!)
+            .put(fileBody)
+
+        return execRequest(request)
+    }
+
+    /**
+     * 执行请求，获取响应结果
+     *
+     * @param requestBuilder 因为还需要追加验证信息，所以此处传递Request.Builder的对象，而不是Request的对象
+     * @return 请求执行的结果
+     */
+    @Throws(IOException::class)
+    private fun execRequest(requestBuilder: Request.Builder): Boolean {
+        val auth = HttpAuth.auth
+        if (auth != null) {
+            requestBuilder.header("Authorization", Credentials.basic(auth!!.user, auth!!.pass))
+        }
+
+        val response = okHttpClient.newCall(requestBuilder.build()).execute()
+        return response.isSuccessful
+    }
+
+    fun canRead(): Boolean {
+        return true
+    }
+
+    fun canWrite(): Boolean {
+        return false
+    }
+
+    fun exists(): Boolean {
+        return exists
+    }
+
+    fun exists(exists: Boolean) {
+        this.exists = exists
+    }
+
+    companion object {
+        val TAG = WebDav::class.java.simpleName
+        val OBJECT_NOT_EXISTS_TAG = "ObjectNotFound"
+        // 指定返回哪些属性
+        private val DIR = "<?xml version=\"1.0\"?>\n" +
+                "<a:propfind xmlns:a=\"DAV:\">\n" +
+                "<a:prop>\n" +
+                "<a:displayname/>\n<a:resourcetype/>\n<a:getcontentlength/>\n<a:creationdate/>\n<a:getlastmodified/>\n%s" +
+                "</a:prop>\n" +
+                "</a:propfind>"
+
+        /**
+         * 打印对象内的所有属性
+         */
+        fun <T> printAllAttrs(className: String, o: Any): T? {
+            try {
+                val c = Class.forName(className)
+                val fields = c.declaredFields
+                for (f in fields) {
+                    f.isAccessible = true
+                }
+                println("=============$className===============")
+                for (f in fields) {
+                    val field = f.toString().substring(f.toString().lastIndexOf(".") + 1) //取出属性名称
+                    println(field + " --> " + f.get(o))
+                }
+            } catch (e: Exception) {
+                e.printStackTrace()
+            }
+
+            return null
+        }
+    }
+}
\ No newline at end of file
diff --git a/app/src/main/java/io/legado/app/lib/webdav/http/Handler.kt b/app/src/main/java/io/legado/app/lib/webdav/http/Handler.kt
new file mode 100644
index 000000000..2bafb9780
--- /dev/null
+++ b/app/src/main/java/io/legado/app/lib/webdav/http/Handler.kt
@@ -0,0 +1,25 @@
+package io.legado.app.lib.webdav.http
+
+import java.net.URL
+import java.net.URLConnection
+import java.net.URLStreamHandler
+
+class Handler : URLStreamHandler() {
+
+    override fun getDefaultPort(): Int {
+        return 80
+    }
+
+    public override fun openConnection(u: URL): URLConnection? {
+        return null
+    }
+
+    override fun parseURL(url: URL, spec: String, start: Int, end: Int) {
+        super.parseURL(url, spec, start, end)
+    }
+
+    companion object {
+
+        val HANDLER: URLStreamHandler = Handler()
+    }
+}
diff --git a/app/src/main/java/io/legado/app/lib/webdav/http/HttpAuth.kt b/app/src/main/java/io/legado/app/lib/webdav/http/HttpAuth.kt
new file mode 100644
index 000000000..3a6f31b48
--- /dev/null
+++ b/app/src/main/java/io/legado/app/lib/webdav/http/HttpAuth.kt
@@ -0,0 +1,14 @@
+package io.legado.app.lib.webdav.http
+
+object HttpAuth {
+
+    var auth: Auth? = null
+        private set
+
+    fun setAuth(user: String, password: String) {
+        auth = Auth(user, password)
+    }
+
+    class Auth internal constructor(val user: String, val pass: String)
+
+}
\ No newline at end of file
diff --git a/app/src/main/java/io/legado/app/lib/webdav/http/OkHttp.kt b/app/src/main/java/io/legado/app/lib/webdav/http/OkHttp.kt
new file mode 100644
index 000000000..f63e6a9bc
--- /dev/null
+++ b/app/src/main/java/io/legado/app/lib/webdav/http/OkHttp.kt
@@ -0,0 +1,19 @@
+package io.legado.app.lib.webdav.http
+
+import okhttp3.OkHttpClient
+
+class OkHttp private constructor() {
+
+    val okHttpClient: OkHttpClient = OkHttpClient.Builder().build()
+
+    private object SingletonHelper {
+        val INSTANCE = OkHttp()
+    }
+
+    companion object {
+
+        val instance: OkHttp
+            get() = SingletonHelper.INSTANCE
+    }
+
+}