Android URL to File Name Convert toFile(URL url)

Description

to File

License

Apache License

Declaration

public static File toFile(URL url) 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import java.io.File;

import java.net.URL;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;

public class Main {
    /**/*from   w w w.jav a2s  . co m*/
     * The UTF-8 character set, used to decode octets in URLs.
     */
    private static final Charset UTF8 = Charset.forName("UTF-8");

    public static File toFile(URL url) {
        if (url == null || !"file".equalsIgnoreCase(url.getProtocol())) {
            return null;
        } else {
            String filename = url.getFile()
                    .replace('/', File.separatorChar);
            filename = decodeUrl(filename);
            return new File(filename);
        }
    }

    /**
     * Decodes the specified URL as per RFC 3986, i.e. transforms
     * percent-encoded octets to characters by decoding with the UTF-8 character
     * set. This function is primarily intended for usage with
     * {@link java.net.URL} which unfortunately does not enforce proper URLs. As
     * such, this method will leniently accept invalid characters or malformed
     * percent-encoded octets and simply pass them literally through to the
     * result string. Except for rare edge cases, this will make unencoded URLs
     * pass through unaltered.
     *
     * @param url  The URL to decode, may be <code>null</code>.
     * @return The decoded URL or <code>null</code> if the input was
     *         <code>null</code>.
     */
    static String decodeUrl(String url) {
        String decoded = url;
        if (url != null && url.indexOf('%') >= 0) {
            int n = url.length();
            StringBuffer buffer = new StringBuffer();
            ByteBuffer bytes = ByteBuffer.allocate(n);
            for (int i = 0; i < n;) {
                if (url.charAt(i) == '%') {
                    try {
                        do {
                            byte octet = (byte) Integer.parseInt(
                                    url.substring(i + 1, i + 3), 16);
                            bytes.put(octet);
                            i += 3;
                        } while (i < n && url.charAt(i) == '%');
                        continue;
                    } catch (RuntimeException e) {
                        // malformed percent-encoded octet, fall through and
                        // append characters literally
                    } finally {
                        if (bytes.position() > 0) {
                            bytes.flip();
                            buffer.append(UTF8.decode(bytes).toString());
                            bytes.clear();
                        }
                    }
                }
                buffer.append(url.charAt(i++));
            }
            decoded = buffer.toString();
        }
        return decoded;
    }
}

Related

1. getFileName(URL url)