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Java example source code file (PublicSuffixListParser.java)

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

Java tags/keywords

arraylist, bufferedreader, collection, immutable, io, ioexception, max_line_len, publicsuffixfilter, publicsuffixlistparser, stringbuilder, util

The PublicSuffixListParser.java example source code

/*
 * $HeadURL$
 * $Revision$
 * $Date$
 *
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 *
 */

package org.apache.http.impl.cookie;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.Reader;
import java.util.ArrayList;
import java.util.Collection;

import org.apache.http.annotation.Immutable;

/**
 * Parses the list from <a href="http://publicsuffix.org/">publicsuffix.org
 * and configures a PublicSuffixFilter.
 *
 * @since 4.0
 */
@Immutable
public class PublicSuffixListParser {
    private static final int MAX_LINE_LEN = 256;
    private final PublicSuffixFilter filter;
    
    PublicSuffixListParser(PublicSuffixFilter filter) {
        this.filter = filter;
    }

    /**
     * Parses the public suffix list format.
     * When creating the reader from the file, make sure to
     * use the correct encoding (the original list is in UTF-8).
     * 
     * @param list the suffix list. The caller is responsible for closing the reader.
     * @throws IOException on error while reading from list
     */
    public void parse(Reader list) throws IOException {
        Collection<String> rules = new ArrayList();
        Collection<String> exceptions = new ArrayList();
        BufferedReader r = new BufferedReader(list);
        StringBuilder sb = new StringBuilder(256);
        boolean more = true;
        while (more) {
            more = readLine(r, sb);
            String line = sb.toString();
            if (line.length() == 0) continue;
            if (line.startsWith("//")) continue; //entire lines can also be commented using //
            if (line.startsWith(".")) line = line.substring(1); // A leading dot is optional
            // An exclamation mark (!) at the start of a rule marks an exception to a previous wildcard rule
            boolean isException = line.startsWith("!"); 
            if (isException) line = line.substring(1);
            
            if (isException) {
                exceptions.add(line);
            } else {
                rules.add(line);
            }
        }
        
        filter.setPublicSuffixes(rules);
        filter.setExceptions(exceptions);
    }
    
    /**
     * 
     * @param r
     * @param sb
     * @return false when the end of the stream is reached
     * @throws IOException
     */
    private boolean readLine(Reader r, StringBuilder sb) throws IOException {
        sb.setLength(0);
        int b;
        boolean hitWhitespace = false;
        while ((b = r.read()) != -1) {
            char c = (char) b;
            if (c == '\n') break;
            // Each line is only read up to the first whitespace
            if (Character.isWhitespace(c)) hitWhitespace = true;
            if (!hitWhitespace) sb.append(c);
            if (sb.length() > MAX_LINE_LEN) throw new IOException("Line too long"); // prevent excess memory usage
        }
        return (b != -1);
    }
}

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