[WebFragment] Fragment with WebView, busy indicator, custom user-agent, and correct fallback when offline. SDK 9 and up #android

fragment_web.xml

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout 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:paddingTop="?attr/actionBarSize">

    <WebView
        android:id="@+id/webview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

    <LinearLayout
        android:id="@+id/vg_offline"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        android:layout_marginLeft="@dimen/activity_horizontal_margin"
        android:layout_marginRight="@dimen/activity_horizontal_margin"
        android:layout_marginTop="@dimen/activity_vertical_margin"
        android:orientation="vertical"
        android:visibility="gone"
        tools:visibility="visible">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_margin="@dimen/activity_horizontal_margin"
            android:gravity="center"
            android:text="@string/tv_no_connection"/>

        <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="wrap_content"
            android:gravity="center_vertical"
            android:orientation="horizontal">

            <Button
                android:id="@+id/bt_refresh"
                android:layout_width="0dp"
                android:layout_height="wrap_content"
                android:layout_weight="1"
                android:drawableLeft="@drawable/ic_refresh"
                android:drawableStart="@drawable/ic_refresh"
                android:padding="@dimen/activity_horizontal_margin"
                android:text="@string/bt_refresh"/>

            <View
                android:id="@+id/divider"
                android:layout_width="2dp"
                android:layout_height="match_parent"
                android:layout_margin="@dimen/activity_horizontal_margin"
                android:background="@color/dark_gray"/>

            <ImageButton
                android:id="@+id/bt_settings"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:contentDescription="@string/bt_settings"
                android:padding="@dimen/activity_horizontal_margin"
                android:src="@drawable/ic_settings"/>
        </LinearLayout>
    </LinearLayout>

    <ProgressBar
        android:id="@+id/pb_web"
        style="?android:attr/progressBarStyleHorizontal"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_marginTop="-6dp"
        android:visibility="gone"
        tools:visibility="visible"/>
</FrameLayout>

WebFragment.java

package com.github.gist.monkeyinmysoup;

import android.annotation.SuppressLint;
import android.content.Context;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.content.pm.PackageManager.NameNotFoundException;
import android.content.pm.ResolveInfo;
import android.net.ConnectivityManager;
import android.net.Uri;
import android.os.Build;
import android.os.Bundle;
import android.support.annotation.Nullable;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.webkit.WebChromeClient;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;
import android.widget.ProgressBar;

import java.net.MalformedURLException;
import java.net.URL;
import java.util.List;

import com.github.gist.monkeyinmysoup.R;

/**
 * Fragment with a WebView and fall-back UI in case there's no active data connection.
 * A url is expected in R.string.web_url.
 * <p/>
 * Compatible with Android SDK 9 and up.
 */
public class WebFragment extends Fragment {

    // Only set to true if you know it will be safe
    private static final boolean ENABLE_JAVASCRIPT = false;
    // Max app cache size. Ignored on SDK 18+
    private static final long APP_CACHE_SIZE = 5 * 1024 * 1024;
    // Set to false to open all links in the webview as well.
    // Otherwise only links within the same domain as the starting url will open in the webview.
    private static final boolean OPEN_LINKS_IN_BROWSER = true;
    private static final boolean ALLOW_LOCAL_STORAGE = true;
    /**
     * User-Agent string. E.g. "AppName/1.0-5 (Android 6.0-23) - LGE Nexus 5"
     */
    private static final String USER_AGENT = "%1$s/%2$s-%3$s (Android %4$s-%5$s) - %6$s %7$s";

    private static final String TAG = WebFragment.class.getSimpleName();

    private boolean mIsWebViewAvailable;
    private boolean mHasFailed = false;
    private String mWebUrl;
    private String mWebDomain;
    private WebView mWebView;
    private ViewGroup mRootView;
    private ProgressBar mProgress;

    public WebFragment() {
    }

    public static WebFragment getInstance() {
        return new WebFragment();
    }

    @SuppressLint("SetJavaScriptEnabled")
    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        // Inflate
        mRootView = (ViewGroup) inflater.inflate(
                R.layout.fragment_web, container, false);
        mWebView = (WebView) mRootView.findViewById(R.id.webview);
        mProgress = (ProgressBar) mRootView.findViewById(R.id.pb_web);
        mWebUrl = getString(R.string.web_url);
        mWebDomain = getDomain(mWebUrl);

        // Retry and Settings buttons
        mRootView.findViewById(R.id.bt_refresh).setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                mHasFailed = false;
                mWebView.loadUrl(mWebUrl);
            }
        });
        mRootView.findViewById(R.id.bt_settings).setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                final Intent intent = new Intent(android.provider.Settings.ACTION_WIRELESS_SETTINGS);
                startActivity(intent);
            }
        });

        // Allow local storage if needed
        if (ALLOW_LOCAL_STORAGE) {
            String databasePath = getActivity().getDir("databases", Context.MODE_PRIVATE).getPath();
            mWebView.getSettings().setDatabasePath(databasePath);
            mWebView.getSettings().setDatabaseEnabled(true);
        }

        mIsWebViewAvailable = true;

        // Custom User Agent
        WebSettings settings = mWebView.getSettings();
        settings.setUserAgentString(getUserAgent());

        // Local caching for offline use
        settings.setAppCacheMaxSize(APP_CACHE_SIZE);
        settings.setAppCachePath(getActivity().getApplicationContext().getCacheDir().getAbsolutePath());
        settings.setAllowFileAccess(true);
        settings.setAppCacheEnabled(true);
        settings.setJavaScriptEnabled(ENABLE_JAVASCRIPT);
        settings.setCacheMode(WebSettings.LOAD_DEFAULT);
        if (!hasConnection()) {
            settings.setCacheMode(WebSettings.LOAD_CACHE_ELSE_NETWORK);
        }

        // Open links in default browser and show offline message when needed
        mWebView.setWebViewClient(new WebViewClient() {

            @Override
            public boolean shouldOverrideUrlLoading(WebView view, String url) {
                mHasFailed = false;
                //noinspection PointlessBooleanExpression
                if (OPEN_LINKS_IN_BROWSER && !isSameDomain(mWebDomain, url)) {
                    Intent browserIntent = new Intent(Intent.ACTION_VIEW, Uri.parse(url));
                    startActivity(browserIntent);
                    return true;
                }
                return false;
            }

            @Override
            public void onPageFinished(WebView view, String url) {
                if (!mHasFailed) {
                    // Hide offline message (if any)
                    mWebView.setVisibility(View.VISIBLE);
                    mRootView.findViewById(R.id.vg_offline).setVisibility(View.GONE);
                }
            }

            @Override
            public void onReceivedError(WebView view, int errorCode, String description, String failingUrl) {
                // Check if we can reach the settings:
                final Intent intent = new Intent(android.provider.Settings.ACTION_WIRELESS_SETTINGS);
                List<ResolveInfo> list = getActivity().getPackageManager().queryIntentActivities(intent, PackageManager.MATCH_DEFAULT_ONLY);
                if (list.size() == 0) {
                    // No? Hide the settings button and divider
                    mRootView.findViewById(R.id.divider).setVisibility(View.GONE);
                    mRootView.findViewById(R.id.bt_settings).setVisibility(View.GONE);
                }
                // Show message:
                mRootView.findViewById(R.id.vg_offline).setVisibility(View.VISIBLE);
                mWebView.setVisibility(View.GONE);
                mHasFailed = true;
            }
        });

        // Configure progress bar
        mWebView.setWebChromeClient(
                new WebChromeClient() {
                    public void onProgressChanged(WebView view, int progress) {
                        if (progress < 100) {
                            mProgress.setVisibility(View.VISIBLE);
                            mProgress.setProgress(progress);
                        } else {
                            mProgress.setVisibility(View.GONE);
                        }
                    }
                });

        // Go!
        mWebView.loadUrl(mWebUrl);

        return mRootView;
    }

    /**
     * Checks if the given url is in the same domain as the given domain
     *
     * @param domain The domain
     * @param url    The url
     * @return
     */
    private boolean isSameDomain(String domain, String url) {
        return domain != null && domain.equals(getDomain(url));
    }

    /**
     * Returns the domain part of a url
     *
     * @param url
     * @return
     */
    private String getDomain(String url) {
        try {
            return new URL(url).getHost();
        } catch (MalformedURLException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * Creates a custom user-agent string in the shape of {@link #USER_AGENT}.
     *
     * @return A string, suitable to be used as the user-agent in the webview
     */
    protected String getUserAgent() {
        int versionCode = 0;
        String versionName = "";
        try {
            versionCode = getActivity().getPackageManager().getPackageInfo(getActivity().getPackageName(), 0).versionCode;
            versionName = getActivity().getPackageManager().getPackageInfo(getActivity().getPackageName(), 0).versionName;
        } catch (NameNotFoundException e) {
            Log.e(TAG, Log.getStackTraceString(e));
        }
        String appName = getString(R.string.app_name);
        return String.format(USER_AGENT,
                appName,
                versionName,
                versionCode,
                Build.VERSION.RELEASE,
                Build.VERSION.SDK_INT,
                Build.MANUFACTURER,
                Build.MODEL);
    }

    /**
     * Checks if there's an active data connection. Does not bother verifying the connection, or to
     * differentiate between WiFi or metered connection.
     *
     * @return {@code true} if the page can probably be loaded.
     */
    public boolean hasConnection() {
        ConnectivityManager man = (ConnectivityManager)
                getActivity().getSystemService(Context.CONNECTIVITY_SERVICE);
        return man.getActiveNetworkInfo() != null;
    }

    @Override
    public void onPause() {
        super.onPause();
        mWebView.onPause();
    }

    @Override
    public void onResume() {
        if (mIsWebViewAvailable) {
            mWebView.onResume();
        }
        super.onResume();
    }

    @Override
    public void onDestroy() {
        mIsWebViewAvailable = false;
        if (mWebView != null) {
            mWebView.destroy();
            mWebView = null;
        }
        super.onDestroy();
    }
}