tsd.client.QueryString.java Source code

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Here is the source code for tsd.client.QueryString.java

Source

// This file is part of OpenTSDB.
// Copyright (C) 2012  The OpenTSDB Authors.
//
// 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 2.1 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 tsd.client;

// I (tsuna) 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 com.google.gwt.http.client.URL;

/**
 * Splits an HTTP query string into a path string and key-value parameter pairs.
 */
public final class QueryString extends HashMap<String, ArrayList<String>> {

    /**
     * Returns the decoded key-value parameter pairs of the URI.
     */
    public static QueryString decode(final String s) {
        final QueryString params = new QueryString();
        String name = null;
        int pos = 0; // Beginning of the unprocessed region
        int i; // End of the unprocessed region
        for (i = 0; i < s.length(); i++) {
            final char 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.
                    params.add(URL.decodeComponent(s.substring(pos, i)), "");
                } else if (name != null) {
                    params.add(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 `='.
                params.add(URL.decodeComponent(s.substring(pos, i)), "");
            } else { // Yes and this must be the last value.
                params.add(name, URL.decodeComponent(s.substring(pos, i)));
            }
        } else if (name != null) { // Have we seen a name without value?
            params.add(name, "");
        }

        return params;
    }

    /**
     * Adds a query string element.
     * @param name The name of the element.
     * @param value The value of the element.
     */
    public void add(final String name, final String value) {
        ArrayList<String> values = super.get(name);
        if (values == null) {
            values = new ArrayList<String>(1); // Often there's only 1 value.
            super.put(name, values);
        }
        values.add(value);
    }

    /**
     * Returns the first value for the given key, or {@code null}.
     */
    public String getFirst(final String key) {
        final ArrayList<String> values = super.get(key);
        return values == null ? null : values.get(0);
    }

}