viewer.QueryStringDecoder.java Source code

Introduction

Here is the source code for viewer.QueryStringDecoder.java

Source

// This file is part of Droopy.
// Copyright (C) 2011  Benoit Sigoure.
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or (at your
// option) any later version.  This program is distributed in the hope that it
// will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty
// of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser
// General Public License for more details.  You should have received a copy
// of the GNU Lesser General Public License along with this program.  If not,
// see <http://www.gnu.org/licenses/>.
package viewer;

// I originally wrote this code for Netty.  Surprisingly, GWT has nothing to
// manually parse query string parameters...

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import com.google.gwt.http.client.URL;

/**
 * Splits an HTTP query string into a path string and key-value parameter pairs.
 */
public final class QueryStringDecoder {

    /**
     * Returns the decoded key-value parameter pairs of the URI.
     */
    public static Map<String, List<String>> getParameters(final String s) {
        final Map<String, List<String>> params = new HashMap<String, List<String>>();
        String name = null;
        int pos = 0; // Beginning of the unprocessed region
        int i; // End of the unprocessed region
        char c = 0; // Current character
        for (i = 0; i < s.length(); i++) {
            c = s.charAt(i);
            if (c == '=' && name == null) {
                if (pos != i) {
                    name = URL.decodeComponent(s.substring(pos, i));
                }
                pos = i + 1;
            } else if (c == '&') {
                if (name == null && pos != i) {
                    // We haven't seen an `=' so far but moved forward.
                    // Must be a param of the form '&a&' so add it with
                    // an empty value.
                    addParam(params, URL.decodeComponent(s.substring(pos, i)), "");
                } else if (name != null) {
                    addParam(params, name, URL.decodeComponent(s.substring(pos, i)));
                    name = null;
                }
                pos = i + 1;
            }
        }

        if (pos != i) { // Are there characters we haven't dealt with?
            if (name == null) { // Yes and we haven't seen any `='.
                addParam(params, URL.decodeComponent(s.substring(pos, i)), "");
            } else { // Yes and this must be the last value.
                addParam(params, name, URL.decodeComponent(s.substring(pos, i)));
            }
        } else if (name != null) { // Have we seen a name without value?
            addParam(params, name, "");
        }

        return params;
    }

    private static void addParam(Map<String, List<String>> params, String name, String value) {
        List<String> values = params.get(name);
        if (values == null) {
            values = new ArrayList<String>(1); // Often there's only 1 value.
            params.put(name, values);
        }
        values.add(value);
    }

}