WebArchiveReader.java

package com.dotcool.reader.helper;

/**
 * Created by Greg Kochaniak, http://www.hyperionics.com
 * License: public domain.
 */
import java.io.ByteArrayInputStream;
import java.io.InputStream;
import java.util.ArrayList;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;
import org.w3c.dom.Text;

import android.util.Base64;
import android.webkit.WebResourceResponse;
import android.webkit.WebSettings;
import android.webkit.WebView;
import android.webkit.WebViewClient;

public abstract class WebArchiveReader {
	private Document myDoc = null;
	private static boolean myLoadingArchive = false;
	private WebView myWebView = null;
	private final ArrayList<String> urlList = new ArrayList<String>();
	private final ArrayList<Element> urlNodes = new ArrayList<Element>();

	protected abstract void onFinished(WebView webView);

	public boolean readWebArchive(InputStream is) {
		DocumentBuilderFactory builderFactory =
				DocumentBuilderFactory.newInstance();
		DocumentBuilder builder = null;
		myDoc = null;
		try {
			builder = builderFactory.newDocumentBuilder();
		} catch (ParserConfigurationException e) {
			e.printStackTrace();
		}
		try {
			myDoc = builder.parse(is);
			NodeList nl = myDoc.getElementsByTagName("url");
			for (int i = 0; i < nl.getLength(); i++) {
				Node nd = nl.item(i);
				if (nd instanceof Element) {
					Element el = (Element) nd;
					// siblings of el (url) are: mimeType, textEncoding, frameName, data
					NodeList nodes = el.getChildNodes();
					for (int j = 0; j < nodes.getLength(); j++) {
						Node node = nodes.item(j);
						if (node instanceof Text) {
							String dt = ((Text) node).getData();
							byte[] b = Base64.decode(dt, Base64.DEFAULT);
							dt = new String(b);
							urlList.add(dt);
							urlNodes.add((Element) el.getParentNode());
						}
					}
				}
			}
		} catch (Exception e) {
			e.printStackTrace();
			myDoc = null;
		}
		return myDoc != null;
	}

	private byte[] getElBytes(Element el, String childName) {
		try {
			Node kid = el.getFirstChild();
			while (kid != null) {
				if (childName.equals(kid.getNodeName())) {
					Node nn = kid.getFirstChild();
					if (nn instanceof Text) {
						String dt = ((Text) nn).getData();
						return Base64.decode(dt, Base64.DEFAULT);
					}
				}
				kid = kid.getNextSibling();
			}
		} catch (Exception e) {
			e.printStackTrace();
		}
		return null;
	}

	public boolean loadToWebView(WebView v) {
		myWebView = v;
		v.setWebViewClient(new WebClient());
		WebSettings webSettings = v.getSettings();
		webSettings.setDefaultTextEncodingName("UTF-8");

		myLoadingArchive = true;
		try {
			// Find the first ArchiveResource in myDoc, should be <ArchiveResource>
			Element ar = (Element) myDoc.getDocumentElement().getFirstChild().getFirstChild();
			byte b[] = getElBytes(ar, "data");

			// Find out the web page charset encoding
			String charset = null;
			String topHtml = new String(b).toLowerCase();
			int n1 = topHtml.indexOf("<meta http-equiv=\"content-type\"");
			if (n1 > -1) {
				int n2 = topHtml.indexOf('>', n1);
				if (n2 > -1) {
					String tag = topHtml.substring(n1, n2);
					n1 = tag.indexOf("charset");
					if (n1 > -1) {
						tag = tag.substring(n1);
						n1 = tag.indexOf('=');
						if (n1 > -1) {
							tag = tag.substring(n1 + 1);
							tag = tag.trim();
							n1 = tag.indexOf('\"');
							if (n1 < 0)
								n1 = tag.indexOf('\'');
							if (n1 > -1) {
								charset = tag.substring(0, n1).trim();
							}
						}
					}
				}
			}

			if (charset != null)
				topHtml = new String(b, charset);
			else {
				topHtml = new String(b);
				/*
				 * CharsetMatch match = new CharsetDetector().setText(b).detect();
				 * if (match != null)
				 * try {
				 * Lt.d("Guessed enc: " + match.getName() + " conf: " + match.getConfidence());
				 * topHtml = new String(b, match.getName());
				 * } catch (UnsupportedEncodingException ue) {
				 * topHtml = new String(b);
				 * }
				 */
			}
			String baseUrl = new String(getElBytes(ar, "url"));
			v.loadDataWithBaseURL(baseUrl, topHtml, "text/html", "UTF-8", null);
		} catch (Exception e) {
			e.printStackTrace();
			return false;
		}
		return true;
	}

	private class WebClient extends WebViewClient {
		@Override
		public WebResourceResponse shouldInterceptRequest(WebView view, String url) {
			if (!myLoadingArchive)
				return null;
			int n = urlList.indexOf(url);
			if (n < 0)
				return null;
			Element parentEl = urlNodes.get(n);
			byte[] b = getElBytes(parentEl, "mimeType");
			String mimeType = b == null ? "text/html" : new String(b);
			b = getElBytes(parentEl, "textEncoding");
			String encoding = b == null ? "UTF-8" : new String(b);
			b = getElBytes(parentEl, "data");
			return new WebResourceResponse(mimeType, encoding, new ByteArrayInputStream(b));
		}

		@Override
		public void onPageFinished(WebView view, String url)
		{
			// our WebClient is no longer needed in view
			view.setWebViewClient(null);
			myLoadingArchive = false;
			onFinished(myWebView);
		}
	}
}