Android WebViewが動かない

PDF Viewerとブラウザを１画面で動作するアプリを作成しています。

画面上部にブラウザを出したいのですが、うまくブラウザが機能しません。
真っ白く表示してしまいます。

問題の原因が分からなくて困っています。
解決策のアドバイスが欲しいです。

なお、manifestには下記を追加しています。
<uses-permission android:name="android.permission.INTERNET"/>

よろしくお願い致します。

Activity.java
1import java.util.HashMap;
2import java.util.Map;
3
4import android.content.ActivityNotFoundException;
5import android.content.Intent;
6import android.content.pm.PackageManager;
7import android.database.Cursor;
8import android.graphics.Color;
9import android.net.Uri;
10import android.os.Bundle;
11import android.provider.OpenableColumns;
12import android.support.annotation.NonNull;
13import android.support.v4.app.ActivityCompat;
14import android.support.v4.content.ContextCompat;
15import android.support.v7.app.AppCompatActivity;
16import android.util.Log;
17import android.widget.Toast;
18
19import com.github.barteksc.pdfviewer.PDFView;
20import com.github.barteksc.pdfviewer.listener.OnLoadCompleteListener;
21import com.github.barteksc.pdfviewer.listener.OnPageChangeListener;
22import com.github.barteksc.pdfviewer.listener.OnPageErrorListener;
23import com.github.barteksc.pdfviewer.scroll.DefaultScrollHandle;
24import com.github.barteksc.pdfviewer.util.FitPolicy;
25import com.shockwave.pdfium.PdfDocument;
26
27import org.androidannotations.annotations.AfterViews;
28import org.androidannotations.annotations.EActivity;
29import org.androidannotations.annotations.NonConfigurationInstance;
30import org.androidannotations.annotations.OnActivityResult;
31import org.androidannotations.annotations.OptionsItem;
32import org.androidannotations.annotations.OptionsMenu;
33import org.androidannotations.annotations.ViewById;
34
35import java.util.List;
36
37
38import android.webkit.WebView;
39import android.webkit.WebViewClient;
40import android.view.KeyEvent;
41
42@EActivity(R.layout.activity_main)
43@OptionsMenu(R.menu.options)
44public class PDFViewActivity extends AppCompatActivity implements OnPageChangeListener, OnLoadCompleteListener,
45        OnPageErrorListener {
46
47    private static final String TAG = PDFViewActivity.class.getSimpleName();
48
49    private final static int REQUEST_CODE = 42;
50    public static final int PERMISSION_CODE = 42042;
51
52    public static final String SAMPLE_FILE = "sample.pdf";
53    public static final String READ_EXTERNAL_STORAGE = "android.permission.READ_EXTERNAL_STORAGE";
54    //
55    //
56    private WebView mainView = null;
57
58    //
59
60    @ViewById
61    PDFView pdfView;
62
63    @NonConfigurationInstance
64    Uri uri;
65
66    @NonConfigurationInstance
67    Integer pageNumber = 0;
68
69    String pdfFileName;
70
71    @OptionsItem(R.id.pickFile)
72    void pickFile() {
73        int permissionCheck = ContextCompat.checkSelfPermission(this,
74                READ_EXTERNAL_STORAGE);
75
76        if (permissionCheck != PackageManager.PERMISSION_GRANTED) {
77            ActivityCompat.requestPermissions(
78                    this,
79                    new String[]{READ_EXTERNAL_STORAGE},
80                    PERMISSION_CODE
81            );
82
83            return;
84        }
85
86        launchPicker();
87    }
88
89    void launchPicker() {
90        Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
91        intent.setType("application/pdf");
92        try {
93            startActivityForResult(intent, REQUEST_CODE);
94        } catch (ActivityNotFoundException e) {
95            //alert user that file manager not working
96            Toast.makeText(this, R.string.toast_pick_file_error, Toast.LENGTH_SHORT).show();
97        }
98    }
99
100    @AfterViews
101    void afterViews() {
102        pdfView.setBackgroundColor(Color.LTGRAY);
103        if (uri != null) {
104            displayFromUri(uri);
105        } else {
106            displayFromAsset(SAMPLE_FILE);
107        }
108        setTitle(pdfFileName);
109    }
110
111    private void displayFromAsset(String assetFileName) {
112        pdfFileName = assetFileName;
113
114        pdfView.fromAsset(SAMPLE_FILE)
115                .defaultPage(pageNumber)
116                .onPageChange(this)
117                .enableAnnotationRendering(true)
118                .onLoad(this)
119                .scrollHandle(new DefaultScrollHandle(this))
120                .spacing(10) // in dp
121                .onPageError(this)
122                .pageFitPolicy(FitPolicy.BOTH)
123                .load();
124    }
125
126    private void displayFromUri(Uri uri) {
127        pdfFileName = getFileName(uri);
128
129        pdfView.fromUri(uri)
130                .defaultPage(pageNumber)
131                .onPageChange(this)
132                .enableAnnotationRendering(true)
133                .onLoad(this)
134                .scrollHandle(new DefaultScrollHandle(this))
135                .spacing(10) // in dp
136                .onPageError(this)
137                .load();
138    }
139
140    @OnActivityResult(REQUEST_CODE)
141    public void onResult(int resultCode, Intent intent) {
142        if (resultCode == RESULT_OK) {
143            uri = intent.getData();
144            displayFromUri(uri);
145        }
146    }
147
148    @Override
149    public void onPageChanged(int page, int pageCount) {
150        pageNumber = page;
151        setTitle(String.format("%s %s / %s", pdfFileName, page + 1, pageCount));
152    }
153
154    public String getFileName(Uri uri) {
155        String result = null;
156        if (uri.getScheme().equals("content")) {
157            Cursor cursor = getContentResolver().query(uri, null, null, null, null);
158            try {
159                if (cursor != null && cursor.moveToFirst()) {
160                    result = cursor.getString(cursor.getColumnIndex(OpenableColumns.DISPLAY_NAME));
161                }
162            } finally {
163                if (cursor != null) {
164                    cursor.close();
165                }
166            }
167        }
168        if (result == null) {
169            result = uri.getLastPathSegment();
170        }
171        return result;
172    }
173
174    @Override
175    public void loadComplete(int nbPages) {
176        PdfDocument.Meta meta = pdfView.getDocumentMeta();
177        Log.e(TAG, "title = " + meta.getTitle());
178        Log.e(TAG, "author = " + meta.getAuthor());
179        Log.e(TAG, "subject = " + meta.getSubject());
180        Log.e(TAG, "keywords = " + meta.getKeywords());
181        Log.e(TAG, "creator = " + meta.getCreator());
182        Log.e(TAG, "producer = " + meta.getProducer());
183        Log.e(TAG, "creationDate = " + meta.getCreationDate());
184        Log.e(TAG, "modDate = " + meta.getModDate());
185
186        printBookmarksTree(pdfView.getTableOfContents(), "-");
187
188    }
189
190    public void printBookmarksTree(List<PdfDocument.Bookmark> tree, String sep) {
191        for (PdfDocument.Bookmark b : tree) {
192
193            Log.e(TAG, String.format("%s %s, p %d", sep, b.getTitle(), b.getPageIdx()));
194
195            if (b.hasChildren()) {
196                printBookmarksTree(b.getChildren(), sep + "-");
197            }
198        }
199    }
200
201    /**
202     * Listener for response to user permission request
203     *
204     * @param requestCode  Check that permission request code matches
205     * @param permissions  Permissions that requested
206     * @param grantResults Whether permissions granted
207     */
208    @Override
209    public void onRequestPermissionsResult(int requestCode, @NonNull String permissions[],
210                                           @NonNull int[] grantResults) {
211        if (requestCode == PERMISSION_CODE) {
212            if (grantResults.length > 0
213                    && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
214                launchPicker();
215            }
216        }
217    }
218
219    @Override
220    public void onPageError(int page, Throwable t) {
221        Log.e(TAG, "Cannot load page " + page);
222    }
223//
224
225//ブラウザ部分
226    @Override
227    protected void onCreate(Bundle savedInstanceState) {
228        super.onCreate(savedInstanceState);
229        setContentView(R.layout.activity_main);
230
231        //コントロール取得
232        this.mainView = (WebView) findViewById(R.id.webView);
233
234        mainView.setWebViewClient(new WebViewClient());
235        //表示URL設定
236        this.mainView.loadUrl("https://google.co.jp/");
237
238    }
239
240    public boolean onKeyDown(int keyCode, KeyEvent event) {
241        // 端末の戻るボタンでブラウザバック
242        if (keyCode == KeyEvent.KEYCODE_BACK && mainView.canGoBack()) {
243            mainView.goBack();
244            return true;
245        }
246        return super.onKeyDown(keyCode, event);
247    }
248
249
250}
251