Query.java

/*
 * Query.java February 2001
 *
 * Copyright (C) 2001, Niall Gallagher <niallg@users.sf.net>
 *
 * 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 org.simpleframework.http;

import java.util.List;
import java.util.Map;

/**
 * The <code>Query</code> object is used to represent HTTP query parameters.
 * Parameters are acquired by name and can be either a string, float, int, or
 * boolean value. This ensures that data can be conveniently extracted in the
 * correct type. This stores the parameters in a map of key value pairs. Each
 * parameter can be acquired using the name of the parameter, if the parameter
 * is named twice then all values can be acquired.
 * 
 * @author Niall Gallagher
 */
public interface Query extends Map<String, String> {

    /**
     * This method is used to acquire a <code>List</code> for all of the
     * parameter values associated with the specified name. Using this method
     * allows the query to expose many values taken from the query or HTTP form
     * posting. Typically the first value in the list is the value from the
     * <code>get(String)</code> method as this is the primary value from the
     * ordered list of values.
     * 
     * @param name
     *            this is the name used to search for the value
     * 
     * @return this is the list of values associated with the key
     */
    List<String> getAll(Object name);

    /**
     * This extracts an integer parameter for the named value. If the named
     * parameter does not exist this will return a zero value. If however the
     * parameter exists but is not in the format of a decimal integer value then
     * this will throw an exception.
     * 
     * @param name
     *            the name of the parameter value to retrieve
     * 
     * @return this returns the named parameter value as an integer
     */
    int getInteger(Object name);

    /**
     * This extracts a float parameter for the named value. If the named
     * parameter does not exist this will return a zero value. If however the
     * parameter exists but is not in the format of a floating point number then
     * this will throw an exception.
     * 
     * @param name
     *            the name of the parameter value to retrieve
     * 
     * @return this returns the named parameter value as a float
     */
    float getFloat(Object name);

    /**
     * This extracts a boolean parameter for the named value. If the named
     * parameter does not exist this will return false otherwise the value is
     * evaluated. If it is either <code>true</code> or <code>false</code> then
     * those boolean values are returned.
     * 
     * @param name
     *            the name of the parameter value to retrieve
     * 
     * @return this returns the named parameter value as an float
     */
    boolean getBoolean(Object name);

    /**
     * This will return all parameters represented using the HTTP URL query
     * format. The <code>x-www-form-urlencoded</code> format is used to encode
     * the attributes, see RFC 2616.
     * <p>
     * This will also encode any special characters that appear within the name
     * and value pairs as an escaped sequence. If there are no parameters an
     * empty string is returned.
     * 
     * @return returns an empty string if the is no parameters
     */
    @Override
    String toString();
}