Android example source code file (URLUtil.java)

This example Android source code file (URLUtil.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

a, android, asset_base, content_disposition_pattern, deprecated, illegalargumentexception, illegalstateexception, internet, invalid, io, logtag, net, network, parseexception, regex, resource_base, string, stringbuilder, urlutil, webaddress

The URLUtil.java Android example source code

/*
 * Copyright (C) 2006 The Android Open Source Project
 *
 * 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
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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 android.webkit;

import java.io.UnsupportedEncodingException;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import android.net.Uri;
import android.net.ParseException;
import android.net.WebAddress;
import android.util.Log;

public final class URLUtil {

    private static final String LOGTAG = "webkit";

    // to refer to bar.png under your package's asset/foo/ directory, use
    // "file:///android_asset/foo/bar.png".
    static final String ASSET_BASE = "file:///android_asset/";
    // to refer to bar.png under your package's res/drawable/ directory, use
    // "file:///android_res/drawable/bar.png". Use "drawable" to refer to
    // "drawable-hdpi" directory as well.
    static final String RESOURCE_BASE = "file:///android_res/";
    static final String FILE_BASE = "file://";
    static final String PROXY_BASE = "file:///cookieless_proxy/";

    /**
     * Cleans up (if possible) user-entered web addresses
     */
    public static String guessUrl(String inUrl) {

        String retVal = inUrl;
        WebAddress webAddress;

        Log.v(LOGTAG, "guessURL before queueRequest: " + inUrl);

        if (inUrl.length() == 0) return inUrl;
        if (inUrl.startsWith("about:")) return inUrl;
        // Do not try to interpret data scheme URLs
        if (inUrl.startsWith("data:")) return inUrl;
        // Do not try to interpret file scheme URLs
        if (inUrl.startsWith("file:")) return inUrl;
        // Do not try to interpret javascript scheme URLs
        if (inUrl.startsWith("javascript:")) return inUrl;

        // bug 762454: strip period off end of url
        if (inUrl.endsWith(".") == true) {
            inUrl = inUrl.substring(0, inUrl.length() - 1);
        }

        try {
            webAddress = new WebAddress(inUrl);
        } catch (ParseException ex) {

            if (DebugFlags.URL_UTIL) {
                Log.v(LOGTAG, "smartUrlFilter: failed to parse url = " + inUrl);
            }
            return retVal;
        }

        // Check host
        if (webAddress.mHost.indexOf('.') == -1) {
            // no dot: user probably entered a bare domain.  try .com
            webAddress.mHost = "www." + webAddress.mHost + ".com";
        }
        return webAddress.toString();
    }

    public static String composeSearchUrl(String inQuery, String template,
                                          String queryPlaceHolder) {
        int placeHolderIndex = template.indexOf(queryPlaceHolder);
        if (placeHolderIndex < 0) {
            return null;
        }

        String query;
        StringBuilder buffer = new StringBuilder();
        buffer.append(template.substring(0, placeHolderIndex));

        try {
            query = java.net.URLEncoder.encode(inQuery, "utf-8");
            buffer.append(query);
        } catch (UnsupportedEncodingException ex) {
            return null;
        }

        buffer.append(template.substring(
                placeHolderIndex + queryPlaceHolder.length()));

        return buffer.toString();
    }

    public static byte[] decode(byte[] url) throws IllegalArgumentException {
        if (url.length == 0) {
            return new byte[0];
        }

        // Create a new byte array with the same length to ensure capacity
        byte[] tempData = new byte[url.length];

        int tempCount = 0;
        for (int i = 0; i < url.length; i++) {
            byte b = url[i];
            if (b == '%') {
                if (url.length - i > 2) {
                    b = (byte) (parseHex(url[i + 1]) * 16
                            + parseHex(url[i + 2]));
                    i += 2;
                } else {
                    throw new IllegalArgumentException("Invalid format");
                }
            }
            tempData[tempCount++] = b;
        }
        byte[] retData = new byte[tempCount];
        System.arraycopy(tempData, 0, retData, 0, tempCount);
        return retData;
    }

    /**
     * @return True iff the url is correctly URL encoded
     */
    static boolean verifyURLEncoding(String url) {
        int count = url.length();
        if (count == 0) {
            return false;
        }

        int index = url.indexOf('%');
        while (index >= 0 && index < count) {
            if (index < count - 2) {
                try {
                    parseHex((byte) url.charAt(++index));
                    parseHex((byte) url.charAt(++index));
                } catch (IllegalArgumentException e) {
                    return false;
                }
            } else {
                return false;
            }
            index = url.indexOf('%', index + 1);
        }
        return true;
    }

    private static int parseHex(byte b) {
        if (b >= '0' && b <= '9') return (b - '0');
        if (b >= 'A' && b <= 'F') return (b - 'A' + 10);
        if (b >= 'a' && b <= 'f') return (b - 'a' + 10);

        throw new IllegalArgumentException("Invalid hex char '" + b + "'");
    }

    /**
     * @return True iff the url is an asset file.
     */
    public static boolean isAssetUrl(String url) {
        return (null != url) && url.startsWith(ASSET_BASE);
    }

    /**
     * @return True iff the url is a resource file.
     * @hide
     */
    public static boolean isResourceUrl(String url) {
        return (null != url) && url.startsWith(RESOURCE_BASE);
    }

    /**
     * @return True iff the url is an proxy url to allow cookieless network 
     * requests from a file url.
     * @deprecated Cookieless proxy is no longer supported.
     */
    @Deprecated
    public static boolean isCookielessProxyUrl(String url) {
        return (null != url) && url.startsWith(PROXY_BASE);
    }

    /**
     * @return True iff the url is a local file.
     */
    public static boolean isFileUrl(String url) {
        return (null != url) && (url.startsWith(FILE_BASE) &&
                                 !url.startsWith(ASSET_BASE) &&
                                 !url.startsWith(PROXY_BASE));
    }

    /**
     * @return True iff the url is an about: url.
     */
    public static boolean isAboutUrl(String url) {
        return (null != url) && url.startsWith("about:");
    }

    /**
     * @return True iff the url is a data: url.
     */
    public static boolean isDataUrl(String url) {
        return (null != url) && url.startsWith("data:");
    }

    /**
     * @return True iff the url is a javascript: url.
     */
    public static boolean isJavaScriptUrl(String url) {
        return (null != url) && url.startsWith("javascript:");
    }

    /**
     * @return True iff the url is an http: url.
     */
    public static boolean isHttpUrl(String url) {
        return (null != url) &&
               (url.length() > 6) &&
               url.substring(0, 7).equalsIgnoreCase("http://");
    }

    /**
     * @return True iff the url is an https: url.
     */
    public static boolean isHttpsUrl(String url) {
        return (null != url) &&
               (url.length() > 7) &&
               url.substring(0, 8).equalsIgnoreCase("https://");
    }

    /**
     * @return True iff the url is a network url.
     */
    public static boolean isNetworkUrl(String url) {
        if (url == null || url.length() == 0) {
            return false;
        }
        return isHttpUrl(url) || isHttpsUrl(url);
    }

    /**
     * @return True iff the url is a content: url.
     */
    public static boolean isContentUrl(String url) {
        return (null != url) && url.startsWith("content:");
    }

    /**
     * @return True iff the url is valid.
     */
    public static boolean isValidUrl(String url) {
        if (url == null || url.length() == 0) {
            return false;
        }

        return (isAssetUrl(url) ||
                isResourceUrl(url) ||
                isFileUrl(url) ||
                isAboutUrl(url) ||
                isHttpUrl(url) ||
                isHttpsUrl(url) ||
                isJavaScriptUrl(url) ||
                isContentUrl(url));
    }

    /**
     * Strips the url of the anchor.
     */
    public static String stripAnchor(String url) {
        int anchorIndex = url.indexOf('#');
        if (anchorIndex != -1) {
            return url.substring(0, anchorIndex);
        }
        return url;
    }
    
    /**
     * Guesses canonical filename that a download would have, using
     * the URL and contentDisposition. File extension, if not defined,
     * is added based on the mimetype
     * @param url Url to the content
     * @param contentDisposition Content-Disposition HTTP header or null
     * @param mimeType Mime-type of the content or null
     * 
     * @return suggested filename
     */
    public static final String guessFileName(
            String url,
            String contentDisposition,
            String mimeType) {
        String filename = null;
        String extension = null;

        // If we couldn't do anything with the hint, move toward the content disposition
        if (filename == null && contentDisposition != null) {
            filename = parseContentDisposition(contentDisposition);
            if (filename != null) {
                int index = filename.lastIndexOf('/') + 1;
                if (index > 0) {
                    filename = filename.substring(index);
                }
            }
        }

        // If all the other http-related approaches failed, use the plain uri
        if (filename == null) {
            String decodedUrl = Uri.decode(url);
            if (decodedUrl != null) {
                int queryIndex = decodedUrl.indexOf('?');
                // If there is a query string strip it, same as desktop browsers
                if (queryIndex > 0) {
                    decodedUrl = decodedUrl.substring(0, queryIndex);
                }
                if (!decodedUrl.endsWith("/")) {
                    int index = decodedUrl.lastIndexOf('/') + 1;
                    if (index > 0) {
                        filename = decodedUrl.substring(index);
                    }
                }
            }
        }

        // Finally, if couldn't get filename from URI, get a generic filename
        if (filename == null) {
            filename = "downloadfile";
        }

        // Split filename between base and extension
        // Add an extension if filename does not have one
        int dotIndex = filename.indexOf('.');
        if (dotIndex < 0) {
            if (mimeType != null) {
                extension = MimeTypeMap.getSingleton().getExtensionFromMimeType(mimeType);
                if (extension != null) {
                    extension = "." + extension;
                }
            }
            if (extension == null) {
                if (mimeType != null && mimeType.toLowerCase().startsWith("text/")) {
                    if (mimeType.equalsIgnoreCase("text/html")) {
                        extension = ".html";
                    } else {
                        extension = ".txt";
                    }
                } else {
                    extension = ".bin";
                }
            }
        } else {
            if (mimeType != null) {
                // Compare the last segment of the extension against the mime type.
                // If there's a mismatch, discard the entire extension.
                int lastDotIndex = filename.lastIndexOf('.');
                String typeFromExt = MimeTypeMap.getSingleton().getMimeTypeFromExtension(
                        filename.substring(lastDotIndex + 1));
                if (typeFromExt != null && !typeFromExt.equalsIgnoreCase(mimeType)) {
                    extension = MimeTypeMap.getSingleton().getExtensionFromMimeType(mimeType);
                    if (extension != null) {
                        extension = "." + extension;
                    }
                }
            }
            if (extension == null) {
                extension = filename.substring(dotIndex);
            }
            filename = filename.substring(0, dotIndex);
        }

        return filename + extension;
    }

    /** Regex used to parse content-disposition headers */
    private static final Pattern CONTENT_DISPOSITION_PATTERN =
            Pattern.compile("attachment;\\s*filename\\s*=\\s*(\"?)([^\"]*)\\1\\s*$",
            Pattern.CASE_INSENSITIVE);

    /*
     * Parse the Content-Disposition HTTP Header. The format of the header
     * is defined here: http://www.w3.org/Protocols/rfc2616/rfc2616-sec19.html
     * This header provides a filename for content that is going to be
     * downloaded to the file system. We only support the attachment type.
     * Note that RFC 2616 specifies the filename value must be double-quoted.
     * Unfortunately some servers do not quote the value so to maintain
     * consistent behaviour with other browsers, we allow unquoted values too.
     */
    static String parseContentDisposition(String contentDisposition) {
        try {
            Matcher m = CONTENT_DISPOSITION_PATTERN.matcher(contentDisposition);
            if (m.find()) {
                return m.group(2);
            }
        } catch (IllegalStateException ex) {
             // This function is defined as returning null when it can't parse the header
        }
        return null;
    }
}