diff --git a/README.md b/README.md
index a580805b..5ca138eb 100644
--- a/README.md
+++ b/README.md
@@ -32,12 +32,23 @@ This is beta release because of big number of small changes and something could
 * removed minimap and mask configuration
 
 ## Installation
+## Step 1. Add the JitPack repository to your build file
+Add it in your root build.gradle at the end of repositories:
+	
+	allprojects {
+		repositories {
+			...
+			maven { url 'https://jitpack.io' }
+		}
+	}
+
+## Step 2. Add the dependency
+	dependencies {
+	        compile 'com.github.shxdos:AndroidPdfViewer:2.7.0-beta.2'
+	}
 
-Add to _build.gradle_:
 
-`compile 'com.github.barteksc:android-pdf-viewer:2.7.0-beta.1'` or `2.6.1` for more stable version
 
-Library is available in jcenter repository, probably it'll be in Maven Central soon.
 
 ## Include PDFView in your layout
 
@@ -53,6 +64,16 @@ Library is available in jcenter repository, probably it'll be in Maven Central s
 All available options with default values:
 ``` java
 pdfView.fromUri(Uri)
+or
+  pdfView.fromUrl("http://www.anweitong.com/upload/document/standard/national_standards/138793918364316200.pdf")
+                        .enableSwipe(true) // allows to block changing pages using swipe
+                        .defaultPage(0)
+                        .onLoad(this) // called after document is loaded and starts to be rendered
+                        .onPageChange(this)
+                        .swipeHorizontal(false)
+                        .enableAntialiasing(true)
+                        .onFileDownload(this)
+                        .loadFromUrl();
 or
 pdfView.fromFile(File)
 or
diff --git a/android-pdf-viewer/build.gradle b/android-pdf-viewer/build.gradle
index 2ec789a0..a85e4e03 100644
--- a/android-pdf-viewer/build.gradle
+++ b/android-pdf-viewer/build.gradle
@@ -39,6 +39,7 @@ android {
 
 dependencies {
     compile 'com.github.barteksc:pdfium-android:1.7.0'
+    compile 'com.squareup.okhttp3:okhttp:3.8.1'
 }
 
 apply from: 'https://raw.githubusercontent.com/nuuneoi/JCenter/master/installv1.gradle'
diff --git a/android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/PDFView.java b/android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/PDFView.java
index d57d9da6..140fff41 100644
--- a/android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/PDFView.java
+++ b/android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/PDFView.java
@@ -28,6 +28,7 @@
 import android.graphics.drawable.Drawable;
 import android.net.Uri;
 import android.os.AsyncTask;
+import android.os.Environment;
 import android.os.HandlerThread;
 import android.util.AttributeSet;
 import android.util.Log;
@@ -35,6 +36,7 @@
 
 import com.github.barteksc.pdfviewer.listener.OnDrawListener;
 import com.github.barteksc.pdfviewer.listener.OnErrorListener;
+import com.github.barteksc.pdfviewer.listener.OnFileDownloadCompleteListener;
 import com.github.barteksc.pdfviewer.listener.OnLoadCompleteListener;
 import com.github.barteksc.pdfviewer.listener.OnPageChangeListener;
 import com.github.barteksc.pdfviewer.listener.OnPageScrollListener;
@@ -47,8 +49,10 @@
 import com.github.barteksc.pdfviewer.source.FileSource;
 import com.github.barteksc.pdfviewer.source.InputStreamSource;
 import com.github.barteksc.pdfviewer.source.UriSource;
+import com.github.barteksc.pdfviewer.source.UrlSource;
 import com.github.barteksc.pdfviewer.util.ArrayUtils;
 import com.github.barteksc.pdfviewer.util.Constants;
+import com.github.barteksc.pdfviewer.util.DownloadUtil;
 import com.github.barteksc.pdfviewer.util.MathUtils;
 import com.github.barteksc.pdfviewer.util.Util;
 import com.shockwave.pdfium.PdfDocument;
@@ -1288,7 +1292,14 @@ public Configurator fromAsset(String assetName) {
     public Configurator fromFile(File file) {
         return new Configurator(new FileSource(file));
     }
-
+    /**
+     * Use a url as the pdf source
+     */
+    public Configurator fromUrl(String url) {
+        Configurator source= new Configurator(new UrlSource(url));
+        source.fileUrl(url);
+        return source;
+    }
     /**
      * Use URI as the pdf source, for use with content providers
      */
@@ -1322,7 +1333,7 @@ private enum State {DEFAULT, LOADED, SHOWN, ERROR}
     public class Configurator {
 
         private final DocumentSource documentSource;
-
+        private String fileUrl;
         private int[] pageNumbers = null;
 
         private boolean enableSwipe = true;
@@ -1334,6 +1345,7 @@ public class Configurator {
         private OnDrawListener onDrawAllListener;
 
         private OnLoadCompleteListener onLoadCompleteListener;
+        private OnFileDownloadCompleteListener onFileDownloadCompleteListener;
 
         private OnErrorListener onErrorListener;
 
@@ -1365,6 +1377,10 @@ public Configurator pages(int... pageNumbers) {
             this.pageNumbers = pageNumbers;
             return this;
         }
+        private Configurator fileUrl(String fileUrl){
+            this.fileUrl=fileUrl;
+            return this;
+        }
 
         public Configurator enableSwipe(boolean enableSwipe) {
             this.enableSwipe = enableSwipe;
@@ -1395,7 +1411,10 @@ public Configurator onLoad(OnLoadCompleteListener onLoadCompleteListener) {
             this.onLoadCompleteListener = onLoadCompleteListener;
             return this;
         }
-
+        public Configurator onFileDownload(OnFileDownloadCompleteListener onFileDownloadCompleteListener) {
+            this.onFileDownloadCompleteListener = onFileDownloadCompleteListener;
+            return this;
+        }
         public Configurator onPageScroll(OnPageScrollListener onPageScrollListener) {
             this.onPageScrollListener = onPageScrollListener;
             return this;
@@ -1468,5 +1487,40 @@ public void load() {
                 PDFView.this.load(documentSource, password, onLoadCompleteListener, onErrorListener);
             }
         }
+        public void loadFromUrl(){
+            final String SDPath = Environment.getExternalStorageDirectory().getAbsolutePath()+"/PDFViewCache/";
+            int index = fileUrl.lastIndexOf("/");
+            String fileName = fileUrl.substring(index);
+            final File file = new File(SDPath, fileName);
+            if(file.exists()){
+                //文件存在
+                if(onFileDownloadCompleteListener!=null){
+                    onFileDownloadCompleteListener.onDownloadComplete(file);
+                }
+                PDFView.this.fromFile(file);
+                load();
+            }else{
+                DownloadUtil.get().download(fileUrl, SDPath, new DownloadUtil.OnDownloadListener() {
+                    @Override
+                    public void onDownloadSuccess(File file) {
+                        if(onFileDownloadCompleteListener!=null){
+                            onFileDownloadCompleteListener.onDownloadComplete(file);
+                        }
+                        PDFView.this.fromFile(file);
+                        load();
+                    }
+
+                    @Override
+                    public void onDownloading(int progress) {
+
+                    }
+
+                    @Override
+                    public void onDownloadFailed() {
+
+                    }
+                });
+            }
+        }
     }
 }
diff --git a/android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/listener/OnFileDownloadCompleteListener.java b/android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/listener/OnFileDownloadCompleteListener.java
new file mode 100644
index 00000000..94fcbd4b
--- /dev/null
+++ b/android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/listener/OnFileDownloadCompleteListener.java
@@ -0,0 +1,31 @@
+/**
+ * Copyright 2016 Bartosz Schiller
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.github.barteksc.pdfviewer.listener;
+
+import java.io.File;
+
+/**
+ * Implement this interface to receive events from PDFView
+ * when the url file loading is complete.
+ */
+public interface OnFileDownloadCompleteListener {
+
+    /**
+     * Called when the PDF is loaded
+     * @param file the number of pages in this PDF file
+     */
+    void onDownloadComplete(File file);
+}
diff --git a/android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/source/UrlSource.java b/android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/source/UrlSource.java
new file mode 100644
index 00000000..5dbe040f
--- /dev/null
+++ b/android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/source/UrlSource.java
@@ -0,0 +1,38 @@
+package com.github.barteksc.pdfviewer.source;
+
+import android.content.Context;
+import android.os.Environment;
+import android.os.ParcelFileDescriptor;
+
+import com.shockwave.pdfium.PdfDocument;
+import com.shockwave.pdfium.PdfiumCore;
+
+import java.io.File;
+import java.io.IOException;
+
+/**
+ * Created by 邵鸿轩 on 2017/7/21.
+ */
+
+public class UrlSource implements DocumentSource {
+    private File file;
+    private String url;
+
+    public UrlSource(String url) {
+        this.url = url;
+    }
+
+    @Override
+    public PdfDocument createDocument(Context context, PdfiumCore core, String password) throws IOException {
+        final String SDPath = Environment.getExternalStorageDirectory().getAbsolutePath() + "/PDFViewCache/";
+        int index = url.lastIndexOf("/");
+        String fileName = url.substring(index);
+        file = new File(SDPath, fileName);
+        if (file.exists()) {
+            ParcelFileDescriptor pfd = ParcelFileDescriptor.open(file, ParcelFileDescriptor.MODE_READ_ONLY);
+            return core.newDocument(pfd, password);
+        }
+        return null;
+
+    }
+}
diff --git a/android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/util/DownloadUtil.java b/android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/util/DownloadUtil.java
new file mode 100644
index 00000000..bddaa0b3
--- /dev/null
+++ b/android-pdf-viewer/src/main/java/com/github/barteksc/pdfviewer/util/DownloadUtil.java
@@ -0,0 +1,133 @@
+package com.github.barteksc.pdfviewer.util;
+
+import android.support.annotation.NonNull;
+
+import java.io.File;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+
+import okhttp3.Call;
+import okhttp3.Callback;
+import okhttp3.OkHttpClient;
+import okhttp3.Request;
+import okhttp3.Response;
+
+public class DownloadUtil {
+
+    private static DownloadUtil downloadUtil;
+    private final OkHttpClient okHttpClient;
+
+    public static DownloadUtil get() {
+        if (downloadUtil == null) {
+            downloadUtil = new DownloadUtil();
+        }
+        return downloadUtil;
+    }
+
+    private DownloadUtil() {
+        okHttpClient = new OkHttpClient();
+    }
+
+    /**
+     * @param url 下载连接
+     * @param saveDir 储存下载文件的SDCard目录
+     * @param listener 下载监听
+     */
+    public void download(final String url, final String saveDir, final OnDownloadListener listener) {
+        Request request = new Request.Builder().url(url).build();
+        okHttpClient.newCall(request).enqueue(new Callback() {
+            @Override
+            public void onFailure(Call call, IOException e) {
+                // 下载失败
+                listener.onDownloadFailed();
+            }
+            @Override
+            public void onResponse(Call call, Response response) throws IOException {
+                InputStream is = null;
+                byte[] buf = new byte[2048];
+                int len = 0;
+                FileOutputStream fos = null;
+                // 储存下载文件的目录
+                String savePath = isExistDir(saveDir);
+                try {
+                    is = response.body().byteStream();
+                    long total = response.body().contentLength();
+
+                    int index = url.lastIndexOf("/");
+                    String fileName = url.substring(index);
+                    final File file = new File(saveDir, fileName);
+                    fos = new FileOutputStream(file);
+                    long sum = 0;
+                    while ((len = is.read(buf)) != -1) {
+                        fos.write(buf, 0, len);
+                        sum += len;
+                        int progress = (int) (sum * 1.0f / total * 100);
+                        // 下载中
+                        listener.onDownloading(progress);
+                    }
+                    fos.flush();
+                    // 下载完成
+                    listener.onDownloadSuccess(file);
+                } catch (Exception e) {
+                    listener.onDownloadFailed();
+                } finally {
+                    try {
+                        if (is != null)
+                            is.close();
+                    } catch (IOException e) {
+                    }
+                    try {
+                        if (fos != null)
+                            fos.close();
+                    } catch (IOException e) {
+                    }
+                }
+            }
+        });
+    }
+
+    /**
+     * @param saveDir
+     * @return
+     * @throws IOException
+     * 判断下载目录是否存在
+     */
+    private String isExistDir(String saveDir) throws IOException {
+        // 下载位置
+        File downloadFile = new File( saveDir);
+        if (!downloadFile.mkdirs()) {
+            downloadFile.createNewFile();
+        }
+        String savePath = downloadFile.getAbsolutePath();
+        return savePath;
+    }
+
+    /**
+     * @param url
+     * @return
+     * 从下载连接中解析出文件名
+     */
+    @NonNull
+    private String getNameFromUrl(String url) {
+        return url.substring(url.lastIndexOf("/") + 1);
+    }
+
+    public interface OnDownloadListener {
+        /**
+         * 下载成功
+         */
+        void onDownloadSuccess(File fiel);
+
+        /**
+         * @param progress
+         * 下载进度
+         */
+        void onDownloading(int progress);
+
+        /**
+         * 下载失败
+         */
+        void onDownloadFailed();
+    }
+}
diff --git a/build.gradle b/build.gradle
index 63272134..9cb085f4 100644
--- a/build.gradle
+++ b/build.gradle
@@ -4,7 +4,7 @@ buildscript {
         jcenter()
     }
     dependencies {
-        classpath 'com.android.tools.build:gradle:2.3.2'
+        classpath 'com.android.tools.build:gradle:2.3.3'
         classpath 'com.jfrog.bintray.gradle:gradle-bintray-plugin:1.7.3'
         classpath 'com.github.dcendents:android-maven-gradle-plugin:1.5'
     }
diff --git a/sample/src/main/AndroidManifest.xml b/sample/src/main/AndroidManifest.xml
index d6ce646c..78e26d92 100644
--- a/sample/src/main/AndroidManifest.xml
+++ b/sample/src/main/AndroidManifest.xml
@@ -2,19 +2,29 @@
 	package="com.github.barteksc.sample">
 
     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
-
+	<uses-permission android:name="android.permission.INTERNET" />
+	<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
+	<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE" />
+	<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
+	<uses-permission android:name="android.permission.ACCESS_WIFI_STATE" />
 	<application
 		android:icon="@drawable/ic_launcher"
 		android:label="@string/app_name"
 		android:theme="@style/Theme.AppCompat.Light">
-		<activity
-			android:name="PDFViewActivity_"
-			android:label="@string/app_name" >
-			<intent-filter>
-				<action android:name="android.intent.action.MAIN" />
-				<category android:name="android.intent.category.LAUNCHER" />
-			</intent-filter>
-		</activity>
+		<!--<activity-->
+			<!--android:name="PDFViewActivity_"-->
+			<!--android:label="@string/app_name" >-->
+			<!--&lt;!&ndash;<intent-filter>&ndash;&gt;-->
+				<!--&lt;!&ndash;<action android:name="android.intent.action.MAIN" />&ndash;&gt;-->
+				<!--&lt;!&ndash;<category android:name="android.intent.category.LAUNCHER" />&ndash;&gt;-->
+			<!--&lt;!&ndash;</intent-filter>&ndash;&gt;-->
+		<!--</activity>-->
+		<activity android:name=".PDFViewActivity">
+            <intent-filter>
+                <action android:name="android.intent.action.MAIN" />
+                <category android:name="android.intent.category.LAUNCHER" />
+            </intent-filter>
+        </activity>
 	</application>
 
 </manifest>
\ No newline at end of file
diff --git a/sample/src/main/java/com/github/barteksc/sample/PDFViewActivity.java b/sample/src/main/java/com/github/barteksc/sample/PDFViewActivity.java
index ed18cea1..6c3c957b 100755
--- a/sample/src/main/java/com/github/barteksc/sample/PDFViewActivity.java
+++ b/sample/src/main/java/com/github/barteksc/sample/PDFViewActivity.java
@@ -15,202 +15,58 @@
  */
 package com.github.barteksc.sample;
 
-import android.content.ActivityNotFoundException;
-import android.content.Intent;
-import android.content.pm.PackageManager;
-import android.database.Cursor;
-import android.graphics.Color;
-import android.net.Uri;
-import android.provider.OpenableColumns;
-import android.support.annotation.NonNull;
-import android.support.v4.app.ActivityCompat;
-import android.support.v4.content.ContextCompat;
+import android.os.Bundle;
+import android.support.annotation.Nullable;
 import android.support.v7.app.AppCompatActivity;
-import android.util.Log;
-import android.widget.Toast;
+import android.view.View;
+import android.widget.Button;
 
 import com.github.barteksc.pdfviewer.PDFView;
+import com.github.barteksc.pdfviewer.listener.OnFileDownloadCompleteListener;
 import com.github.barteksc.pdfviewer.listener.OnLoadCompleteListener;
 import com.github.barteksc.pdfviewer.listener.OnPageChangeListener;
-import com.github.barteksc.pdfviewer.scroll.DefaultScrollHandle;
-import com.shockwave.pdfium.PdfDocument;
 
-import org.androidannotations.annotations.AfterViews;
-import org.androidannotations.annotations.EActivity;
-import org.androidannotations.annotations.NonConfigurationInstance;
-import org.androidannotations.annotations.OnActivityResult;
-import org.androidannotations.annotations.OptionsItem;
-import org.androidannotations.annotations.OptionsMenu;
-import org.androidannotations.annotations.ViewById;
+import java.io.File;
 
-import java.util.List;
 
-@EActivity(R.layout.activity_main)
-@OptionsMenu(R.menu.options)
-public class PDFViewActivity extends AppCompatActivity implements OnPageChangeListener, OnLoadCompleteListener {
-
-    private static final String TAG = PDFViewActivity.class.getSimpleName();
-
-    private final static int REQUEST_CODE = 42;
-    public static final int PERMISSION_CODE = 42042;
-
-    public static final String SAMPLE_FILE = "sample.pdf";
-    public static final String READ_EXTERNAL_STORAGE = "android.permission.READ_EXTERNAL_STORAGE";
-
-    @ViewById
+public class PDFViewActivity extends AppCompatActivity implements OnPageChangeListener, OnLoadCompleteListener ,OnFileDownloadCompleteListener{
     PDFView pdfView;
-
-    @NonConfigurationInstance
-    Uri uri;
-
-    @NonConfigurationInstance
-    Integer pageNumber = 0;
-
-    String pdfFileName;
-
-    @OptionsItem(R.id.pickFile)
-    void pickFile() {
-        int permissionCheck = ContextCompat.checkSelfPermission(this,
-                READ_EXTERNAL_STORAGE);
-
-        if (permissionCheck != PackageManager.PERMISSION_GRANTED) {
-            ActivityCompat.requestPermissions(
-                    this,
-                    new String[]{READ_EXTERNAL_STORAGE},
-                    PERMISSION_CODE
-            );
-
-            return;
-        }
-
-        launchPicker();
-    }
-
-    void launchPicker() {
-        Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
-        intent.setType("application/pdf");
-        try {
-            startActivityForResult(intent, REQUEST_CODE);
-        } catch (ActivityNotFoundException e) {
-            //alert user that file manager not working
-            Toast.makeText(this, R.string.toast_pick_file_error, Toast.LENGTH_SHORT).show();
-        }
-    }
-
-    @AfterViews
-    void afterViews() {
-        pdfView.setBackgroundColor(Color.LTGRAY);
-        if (uri != null) {
-            displayFromUri(uri);
-        } else {
-            displayFromAsset(SAMPLE_FILE);
-        }
-        setTitle(pdfFileName);
-    }
-
-    private void displayFromAsset(String assetFileName) {
-        pdfFileName = assetFileName;
-
-        pdfView.fromAsset(SAMPLE_FILE)
-                .defaultPage(pageNumber)
-                .onPageChange(this)
-                .enableAnnotationRendering(true)
-                .onLoad(this)
-                .scrollHandle(new DefaultScrollHandle(this))
-                .spacing(10) // in dp
-                .load();
-    }
-
-    private void displayFromUri(Uri uri) {
-        pdfFileName = getFileName(uri);
-
-        pdfView.fromUri(uri)
-                .defaultPage(pageNumber)
-                .onPageChange(this)
-                .enableAnnotationRendering(true)
-                .onLoad(this)
-                .scrollHandle(new DefaultScrollHandle(this))
-                .spacing(10) // in dp
-                .load();
-    }
-
-    @OnActivityResult(REQUEST_CODE)
-    public void onResult(int resultCode, Intent intent) {
-        if (resultCode == RESULT_OK) {
-            uri = intent.getData();
-            displayFromUri(uri);
-        }
-    }
+    private Button btnLoad;
 
     @Override
-    public void onPageChanged(int page, int pageCount) {
-        pageNumber = page;
-        setTitle(String.format("%s %s / %s", pdfFileName, page + 1, pageCount));
-    }
-
-    public String getFileName(Uri uri) {
-        String result = null;
-        if (uri.getScheme().equals("content")) {
-            Cursor cursor = getContentResolver().query(uri, null, null, null, null);
-            try {
-                if (cursor != null && cursor.moveToFirst()) {
-                    result = cursor.getString(cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME));
-                }
-            } finally {
-                if (cursor != null) {
-                    cursor.close();
-                }
+    protected void onCreate(@Nullable Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.activity_main);
+        pdfView= (PDFView) findViewById(R.id.pdfView);
+        btnLoad= (Button) findViewById(R.id.btnLoad);
+        btnLoad.setOnClickListener(new View.OnClickListener() {
+            @Override
+            public void onClick(View v) {
+                pdfView.fromUrl("http://www.anweitong.com/upload/document/standard/national_standards/138793918364316200.pdf")
+                        .enableSwipe(true) // allows to block changing pages using swipe
+                        .defaultPage(0)
+                        .onLoad(PDFViewActivity.this) // called after document is loaded and starts to be rendered
+                        .onPageChange(PDFViewActivity.this)
+                        .swipeHorizontal(false)
+                        .enableAntialiasing(true)
+                        .onFileDownload(PDFViewActivity.this)
+                        .loadFromUrl();
             }
-        }
-        if (result == null) {
-            result = uri.getLastPathSegment();
-        }
-        return result;
+        });
     }
 
     @Override
     public void loadComplete(int nbPages) {
-        PdfDocument.Meta meta = pdfView.getDocumentMeta();
-        Log.e(TAG, "title = " + meta.getTitle());
-        Log.e(TAG, "author = " + meta.getAuthor());
-        Log.e(TAG, "subject = " + meta.getSubject());
-        Log.e(TAG, "keywords = " + meta.getKeywords());
-        Log.e(TAG, "creator = " + meta.getCreator());
-        Log.e(TAG, "producer = " + meta.getProducer());
-        Log.e(TAG, "creationDate = " + meta.getCreationDate());
-        Log.e(TAG, "modDate = " + meta.getModDate());
-
-        printBookmarksTree(pdfView.getTableOfContents(), "-");
 
     }
 
-    public void printBookmarksTree(List<PdfDocument.Bookmark> tree, String sep) {
-        for (PdfDocument.Bookmark b : tree) {
-
-            Log.e(TAG, String.format("%s %s, p %d", sep, b.getTitle(), b.getPageIdx()));
+    @Override
+    public void onPageChanged(int page, int pageCount) {
 
-            if (b.hasChildren()) {
-                printBookmarksTree(b.getChildren(), sep + "-");
-            }
-        }
     }
 
-    /**
-     * Listener for response to user permission request
-     *
-     * @param requestCode  Check that permission request code matches
-     * @param permissions  Permissions that requested
-     * @param grantResults Whether permissions granted
-     */
     @Override
-    public void onRequestPermissionsResult(int requestCode, @NonNull String permissions[],
-                                           @NonNull int[] grantResults) {
-        if (requestCode == PERMISSION_CODE) {
-            if (grantResults.length > 0
-                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
-                launchPicker();
-            }
-        }
-    }
+    public void onDownloadComplete(File file) {
 
+    }
 }
diff --git a/sample/src/main/res/layout/activity_main.xml b/sample/src/main/res/layout/activity_main.xml
index a14dd73d..657a76c8 100644
--- a/sample/src/main/res/layout/activity_main.xml
+++ b/sample/src/main/res/layout/activity_main.xml
@@ -1,11 +1,17 @@
-<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 	xmlns:tools="http://schemas.android.com/tools"
 	android:layout_width="match_parent"
-	android:layout_height="match_parent">
-
+	android:layout_height="match_parent"
+	android:orientation="vertical">
+	<Button
+		android:id="@+id/btnLoad"
+		android:layout_width="match_parent"
+		android:layout_height="wrap_content"
+		android:text="加载"/>
     <com.github.barteksc.pdfviewer.PDFView
         android:id="@+id/pdfView"
+		android:layout_weight="1"
         android:layout_width="match_parent"
         android:layout_height="match_parent" />
 
-</RelativeLayout>
\ No newline at end of file
+</LinearLayout>
\ No newline at end of file