KvpParser.java

/* Copyright (c) 2001 - 2007 TOPP - www.openplans.org. All rights reserved.
 * This code is licensed under the GPL 2.0 license, availible at the root
 * application directory.
 */
package org.geoserver.ows;

import java.util.logging.Logger;

import org.geotools.util.Version;


/**
 * Parses a key-value pair into a key-object pair.
 * <p>
 * This class is intended to be subclassed. Subclasses need declare the key in
 * which they parse, and the type of object they parse into.
 * </p>
 * <p>
 * Instances need to be declared in a spring context like the following:
 * <pre>
 *         <code>
 *  <bean id="myKvpParser" class="org.xzy.MyKvpParser"/>
 *         </code>
 * </pre>
 * Where <code>com.xzy.MyKvpParser</code> could be something like:
 * <pre>
 *         <code>
 *  public class MyKvpParser extends KvpParser {
 *
 *     public MyKvpParser() {
 *        super( "MyKvp", MyObject.class )l
 *     }
 *
 *     public Object parse( String value ) {
 *        return new MyObject( value );
 *     }
 *  }
 *         </code>
 * </pre>
 * </p>
 * <p>
 * <h4>Operation Binding</h4>
 * In the normal case, a kvp parser is engaged when a request specifies a name
 * which matches the name declared by the kvp parser. It is also possible to attach 
 * a kvp parser so that it only engages on a particular operation. This is done by 
 * declaring the one or more of the following:
 * <ul>
 *   <li>service
 *   <li>version
 *   <li>request
 *  </ul>
 * When a kvp parser declares one or more of these properties, it will only 
 * be engaged if an incoming request specicfies matching values of the properties. 
 * </p>
 * <p>
 * The following bean declaration would create the above kvp parser so that it
 * only engages when the service is "MyService", and the request is "MyRequest".
 * <pre>
 *         <code>
 *  <bean id="myKvpParser" class="org.xzy.MyKvpParser">
 *    <property name="service">MyService</property>
 *    <property name="request">MyRequest</property>
 *  <bean>
 *         </code>
 * </pre>
 * </p>
 * @author Justin Deoliveira, The Open Planning Project, jdeolive@openplans.org
 *
 */
public abstract class KvpParser {
    /**
     * logger
     */
    protected static Logger LOGGER = org.geotools.util.logging.Logging.getLogger("org.geoserver.ows");

    /**
     * The key.
     */
    String key;

    /**
     * The class of parsed objects.
     */
    Class binding;

    /**
     * The service to bind to
     */
    String service;
    
    /**
     * The version of the service to bind to
     */
    Version version;
    
    /**
     * The request to bind to
     */
    String request;
    
    public KvpParser(String key, Class binding) {
        this.key = key;
        this.binding = binding;
    }

    /**
     * @return The name of the key the parser binds to.
     */
    public String getKey() {
        return key;
    }

    /**
     * @return The type of parsed objects.
     */
    protected Class getBinding() {
        return binding;
    }
    
    /**
     * @return The service to bind to, may be <code>null</code>.
     */
    public final String getService() {
        return service;
    }
    
    /**
     * Sets the service to bind to.
     */
    public final void setService( String service ) {
        this.service = service;
    }
    
    /**
     * @return The version to bind to, or <code>null</code>.
     */
    public final Version getVersion() {
        return version;
    }
    
    /**
     * Sets the version to bind to.
     */
    public final void setVersion( Version version ) {
        this.version = version;
    }
    
    /**
     * Sets the request to bind to.
     */
    public final void setRequest(String request) {
        this.request = request;
    }
    
    /**
     * @return The request to bind to, or <code>null</code>.
     */
    public String getRequest() {
        return request;
    }

    /**
     * Parses the string representation into the object representation.
     *
     * @param value The string value.
     *
     * @return The parsed object, or null if it could not be parsed.
     *
     * @throws Exception In the event of an unsuccesful parse.
     */
    public abstract Object parse(String value) throws Exception;
}