1 /*
2  * Copyright (C) 2008 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 
17 package com.android.htmlviewer;
18 
19 import android.app.Activity;
20 import android.content.ActivityNotFoundException;
21 import android.content.ContentResolver;
22 import android.content.Intent;
23 import android.content.pm.PackageManager;
24 import android.Manifest;
25 import android.net.Uri;
26 import android.os.Bundle;
27 import android.util.Log;
28 import android.view.View;
29 import android.webkit.WebChromeClient;
30 import android.webkit.WebResourceRequest;
31 import android.webkit.WebResourceResponse;
32 import android.webkit.WebSettings;
33 import android.webkit.WebView;
34 import android.webkit.WebViewClient;
35 import android.widget.Toast;
36 
37 import java.io.IOException;
38 import java.io.InputStream;
39 import java.net.URISyntaxException;
40 import java.util.zip.GZIPInputStream;
41 
42 /**
43  * Simple activity that shows the requested HTML page. This utility is
44  * purposefully very limited in what it supports, including no network or
45  * JavaScript.
46  */
47 public class HTMLViewerActivity extends Activity {
48     private static final String TAG = "HTMLViewer";
49 
50     private WebView mWebView;
51     private View mLoading;
52     private Intent mIntent;
53 
54     @Override
onCreate(Bundle savedInstanceState)55     protected void onCreate(Bundle savedInstanceState) {
56         super.onCreate(savedInstanceState);
57 
58         setContentView(R.layout.main);
59 
60         mWebView = (WebView) findViewById(R.id.webview);
61         mLoading = findViewById(R.id.loading);
62 
63         mWebView.setWebChromeClient(new ChromeClient());
64         mWebView.setWebViewClient(new ViewClient());
65 
66         WebSettings s = mWebView.getSettings();
67         s.setUseWideViewPort(true);
68         s.setSupportZoom(true);
69         s.setBuiltInZoomControls(true);
70         s.setDisplayZoomControls(false);
71         s.setSavePassword(false);
72         s.setSaveFormData(false);
73         s.setBlockNetworkLoads(true);
74 
75         // Javascript is purposely disabled, so that nothing can be
76         // automatically run.
77         s.setJavaScriptEnabled(false);
78         s.setDefaultTextEncodingName("utf-8");
79 
80         mIntent = getIntent();
81         requestPermissionAndLoad();
82     }
83 
loadUrl()84     private void loadUrl() {
85         if (mIntent.hasExtra(Intent.EXTRA_TITLE)) {
86             setTitle(mIntent.getStringExtra(Intent.EXTRA_TITLE));
87         }
88         mWebView.loadUrl(String.valueOf(mIntent.getData()));
89     }
90 
requestPermissionAndLoad()91     private void requestPermissionAndLoad() {
92         Uri destination = mIntent.getData();
93         if (destination != null) {
94             // Is this a local file?
95             if ("file".equals(destination.getScheme())
96                         && PackageManager.PERMISSION_DENIED ==
97                                 checkSelfPermission(Manifest.permission.READ_EXTERNAL_STORAGE)) {
98                 requestPermissions(new String[] {Manifest.permission.READ_EXTERNAL_STORAGE}, 0);
99             } else {
100                 loadUrl();
101             }
102         }
103     }
104 
105     @Override
onRequestPermissionsResult(int requestCode, String permissions[], int[] grantResults)106     public void onRequestPermissionsResult(int requestCode,
107             String permissions[], int[] grantResults) {
108         // We only ever request 1 permission, so these arguments should always have the same form.
109         assert permissions.length == 1;
110         assert Manifest.permission.READ_EXTERNAL_STORAGE.equals(permissions[0]);
111 
112         if (grantResults.length == 1 && PackageManager.PERMISSION_GRANTED == grantResults[0]) {
113             // Try again now that we have the permission.
114             loadUrl();
115         } else {
116             Toast.makeText(HTMLViewerActivity.this,
117                     R.string.turn_on_storage_permission, Toast.LENGTH_SHORT).show();
118             finish();
119         }
120     }
121 
122     @Override
onDestroy()123     protected void onDestroy() {
124         super.onDestroy();
125         mWebView.destroy();
126     }
127 
128     private class ChromeClient extends WebChromeClient {
129         @Override
onReceivedTitle(WebView view, String title)130         public void onReceivedTitle(WebView view, String title) {
131             if (!getIntent().hasExtra(Intent.EXTRA_TITLE)) {
132                 HTMLViewerActivity.this.setTitle(title);
133             }
134         }
135     }
136 
137     private class ViewClient extends WebViewClient {
138         @Override
onPageFinished(WebView view, String url)139         public void onPageFinished(WebView view, String url) {
140             mLoading.setVisibility(View.GONE);
141         }
142 
143         @Override
shouldOverrideUrlLoading(WebView view, String url)144         public boolean shouldOverrideUrlLoading(WebView view, String url) {
145             Intent intent;
146             // Perform generic parsing of the URI to turn it into an Intent.
147             try {
148                 intent = Intent.parseUri(url, Intent.URI_INTENT_SCHEME);
149             } catch (URISyntaxException ex) {
150                 Log.w(TAG, "Bad URI " + url + ": " + ex.getMessage());
151                 Toast.makeText(HTMLViewerActivity.this,
152                         R.string.cannot_open_link, Toast.LENGTH_SHORT).show();
153                 return true;
154             }
155             // Sanitize the Intent, ensuring web pages can not bypass browser
156             // security (only access to BROWSABLE activities).
157             intent.addCategory(Intent.CATEGORY_BROWSABLE);
158             intent.setComponent(null);
159             Intent selector = intent.getSelector();
160             if (selector != null) {
161                 selector.addCategory(Intent.CATEGORY_BROWSABLE);
162                 selector.setComponent(null);
163             }
164 
165             try {
166                 view.getContext().startActivity(intent);
167             } catch (ActivityNotFoundException ex) {
168                 Log.w(TAG, "No application can handle " + url);
169                 Toast.makeText(HTMLViewerActivity.this,
170                         R.string.cannot_open_link, Toast.LENGTH_SHORT).show();
171             }
172             return true;
173         }
174 
175         @Override
shouldInterceptRequest(WebView view, WebResourceRequest request)176         public WebResourceResponse shouldInterceptRequest(WebView view,
177                 WebResourceRequest request) {
178             final Uri uri = request.getUrl();
179             if (ContentResolver.SCHEME_FILE.equals(uri.getScheme())
180                     && uri.getPath().endsWith(".gz")) {
181                 Log.d(TAG, "Trying to decompress " + uri + " on the fly");
182                 try {
183                     final InputStream in = new GZIPInputStream(
184                             getContentResolver().openInputStream(uri));
185                     final WebResourceResponse resp = new WebResourceResponse(
186                             getIntent().getType(), "utf-8", in);
187                     resp.setStatusCodeAndReasonPhrase(200, "OK");
188                     return resp;
189                 } catch (IOException e) {
190                     Log.w(TAG, "Failed to decompress; falling back", e);
191                 }
192             }
193             return null;
194         }
195     }
196 }
197