org.springframework.web.servlet.handler.AbstractHandlerMapping.java Source code

Introduction

Here is the source code for org.springframework.web.servlet.handler.AbstractHandlerMapping.java

Source

/*
 * Copyright 2002-2005 the original author or authors.
 * 
 * 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.springframework.web.servlet.handler;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;

import org.springframework.core.Ordered;
import org.springframework.web.context.support.WebApplicationObjectSupport;
import org.springframework.web.servlet.HandlerExecutionChain;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.HandlerMapping;

/**
 * Abstract base class for HandlerMapping implementations.
 * Supports ordering, a default handler, and handler interceptors.
 *
 * @author Juergen Hoeller
 * @since 07.04.2003
 * @see #getHandlerInternal
 * @see org.springframework.web.servlet.HandlerInterceptor
 */
public abstract class AbstractHandlerMapping extends WebApplicationObjectSupport
        implements HandlerMapping, Ordered {

    protected final Log logger = LogFactory.getLog(getClass());

    private int order = Integer.MAX_VALUE; // default: same as non-Ordered

    private Object defaultHandler;

    private HandlerInterceptor[] interceptors;

    public final void setOrder(int order) {
        this.order = order;
    }

    public final int getOrder() {
        return order;
    }

    /**
     * Set the default handler for this handler mapping.
     * This handler will be returned if no specific mapping was found.
     * <p>Default is <code>null</code>, indicating no default handler.
     * @param defaultHandler default handler instance, or <code>null</code> if none
     */
    public final void setDefaultHandler(Object defaultHandler) {
        this.defaultHandler = defaultHandler;
        logger.info("Default mapping to handler [" + this.defaultHandler + "]");
    }

    /**
     * Return the default handler for this handler mapping.
     * @return the default handler instance, or <code>null</code> if none
     */
    protected final Object getDefaultHandler() {
        return defaultHandler;
    }

    /**
     * Set the handler interceptors to apply for all handlers mapped by
     * this handler mapping.
     * @param interceptors array of handler interceptors, or <code>null</code> if none
     */
    public final void setInterceptors(HandlerInterceptor[] interceptors) {
        this.interceptors = interceptors;
    }

    /**
     * Look up a handler for the given request, falling back to the default
     * handler if no specific one is found.
     * @param request current HTTP request
     * @return the looked up handler instance, or the default handler
     * @see #getHandlerInternal
     */
    public final HandlerExecutionChain getHandler(HttpServletRequest request) throws Exception {
        Object handler = getHandlerInternal(request);
        if (handler == null) {
            handler = this.defaultHandler;
        }
        if (handler == null) {
            return null;
        }
        // bean name of resolved handler?
        if (handler instanceof String) {
            String handlerName = (String) handler;
            handler = getApplicationContext().getBean(handlerName);
        }
        return new HandlerExecutionChain(handler, this.interceptors);
    }

    /**
     * Lookup a handler for the given request, returning null if no specific
     * one is found. This method is called by getHandler, a null return value
     * will lead to the default handler, if one is set.
     * @param request current HTTP request
     * @return the looked up handler instance, or <code>null</code>
     * @throws Exception if there is an internal error
     */
    protected abstract Object getHandlerInternal(HttpServletRequest request) throws Exception;

}