multiactioncontroller.java

spring api 源代码

/*
 * Copyright 2002-2008 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.mvc.multiaction;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import javax.servlet.ServletRequest;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;

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

import org.springframework.beans.BeanUtils;
import org.springframework.util.Assert;
import org.springframework.validation.ValidationUtils;
import org.springframework.validation.Validator;
import org.springframework.web.HttpSessionRequiredException;
import org.springframework.web.bind.ServletRequestDataBinder;
import org.springframework.web.servlet.ModelAndView;
import org.springframework.web.servlet.mvc.AbstractController;
import org.springframework.web.servlet.mvc.LastModified;
import org.springframework.web.util.NestedServletException;

/**
 * {@link org.springframework.web.servlet.mvc.Controller Controller}
 * implementation that allows multiple request types to be handled by the same
 * class. Subclasses of this class can handle several different types of
 * request with methods of the form
 *
 * <pre class="code">public (ModelAndView | Map | void) actionName(HttpServletRequest request, HttpServletResponse response);</pre>
 *
 * May take a third parameter (of type {@link HttpSession}) in which an
 * existing session will be required, or a third parameter of an arbitrary
 * class that gets treated as the command (that is, an instance of the class
 * gets created, and request parameters get bound to it)
 *
 * <p>These methods can throw any kind of exception, but should only let
 * propagate those that they consider fatal, or which their class or superclass
 * is prepared to catch by implementing an exception handler.
 *
 * <p>When returning just a {@link Map} instance view name translation will be
 * used to generate the view name. The configured
 * {@link org.springframework.web.servlet.RequestToViewNameTranslator} will be
 * used to determine the view name.
 *
 * <p>When returning <code>void</code> a return value of <code>null</code> is
 * assumed meaning that the handler method is responsible for writing the
 * response directly to the supplied {@link HttpServletResponse}.
 *
 * <p>This model allows for rapid coding, but loses the advantage of
 * compile-time checking. It is similar to a Struts <code>DispatchAction</code>,
 * but more sophisticated. Also supports delegation to another object.
 *
 * <p>An implementation of the {@link MethodNameResolver} interface defined in
 * this package should return a method name for a given request, based on any
 * aspect of the request, such as its URL or an "action" parameter. The actual
 * strategy can be configured via the "methodNameResolver" bean property, for
 * each <code>MultiActionController</code>.
 *
 * <p>The default <code>MethodNameResolver</code> is
 * {@link InternalPathMethodNameResolver}; further included strategies are
 * {@link PropertiesMethodNameResolver} and {@link ParameterMethodNameResolver}.
 *
 * <p>Subclasses can implement custom exception handler methods with names such
 * as:
 *
 * <pre class="code">public ModelAndView anyMeaningfulName(HttpServletRequest request, HttpServletResponse response, ExceptionClass exception);</pre>
 *
 * The third parameter can be any subclass or {@link Exception} or
 * {@link RuntimeException}.
 *
 * <p>There can also be an optional <code>xxxLastModified</code> method for
 * handlers, of signature:
 *
 * <pre class="code">public long anyMeaningfulNameLastModified(HttpServletRequest request)</pre>
 *
 * If such a method is present, it will be invoked. Default return from
 * <code>getLastModified</code> is -1, meaning that the content must always be
 * regenerated.
 *
 * <p><b>Note that all handler methods need to be public and that
 * method overloading is <i>not</i> allowed.</b>
 *
 * <p>See also the description of the workflow performed by
 * {@link AbstractController the superclass} (in that section of the class
 * level Javadoc entitled 'workflow').
 *
 * <p><b>Note:</b> For maximum data binding flexibility, consider direct usage of a
 * {@link ServletRequestDataBinder} in your controller method, instead of relying
 * on a declared command argument. This allows for full control over the entire
 * binder setup and usage, including the invocation of {@link Validator Validators}
 * and the subsequent evaluation of binding/validation errors.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Colin Sampaleanu
 * @author Rob Harrop
 * @see MethodNameResolver
 * @see InternalPathMethodNameResolver
 * @see PropertiesMethodNameResolver
 * @see ParameterMethodNameResolver
 * @see org.springframework.web.servlet.mvc.LastModified#getLastModified
 * @see org.springframework.web.bind.ServletRequestDataBinder
 */
public class MultiActionController extends AbstractController implements LastModified {

	/** Suffix for last-modified methods */
	public static final String LAST_MODIFIED_METHOD_SUFFIX = "LastModified";

	/** Default command name used for binding command objects: "command" */
	public static final String DEFAULT_COMMAND_NAME = "command";

	/**
	 * Log category to use when no mapped handler is found for a request.
	 * @see #pageNotFoundLogger
	 */
	public static final String PAGE_NOT_FOUND_LOG_CATEGORY = "org.springframework.web.servlet.PageNotFound";

	/**
	 * Additional logger to use when no mapped handler is found for a request.
	 * @see #PAGE_NOT_FOUND_LOG_CATEGORY
	 */
	protected static final Log pageNotFoundLogger = LogFactory.getLog(PAGE_NOT_FOUND_LOG_CATEGORY);

	/** Object we'll invoke methods on. Defaults to this. */
	private Object delegate;

	/**
	 * Helper object that knows how to return method names from incoming requests.
	 */
	private MethodNameResolver methodNameResolver = new InternalPathMethodNameResolver();

	/** List of Validators to apply to commands */
	private Validator[] validators;

	/** Methods, keyed by name */
	private Map handlerMethodMap = new HashMap();

	/** LastModified methods, keyed by handler method name (without LAST_MODIFIED_SUFFIX) */
	private Map lastModifiedMethodMap = new HashMap();

	/** Methods, keyed by exception class */
	private Map exceptionHandlerMap = new HashMap();


	/**
	 * Constructor for <code>MultiActionController</code> that looks for
	 * handler methods in the present subclass.
	 */
	public MultiActionController() {
		this.delegate = this;
		registerHandlerMethods(this.delegate);
		// We'll accept no handler methods found here - a delegate might be set later on.
	}

	/**
	 * Constructor for <code>MultiActionController</code> that looks for
	 * handler methods in delegate, rather than a subclass of this class.
	 * @param delegate handler object. This does not need to implement any
	 * particular interface, as everything is done using reflection.
	 */
	public MultiActionController(Object delegate) {
		setDelegate(delegate);
	}


	/**
	 * Set the delegate used by this class; the default is <code>this</code>,
	 * assuming that handler methods have been added by a subclass.
	 * <p>This method does not get invoked once the class is configured.
	 * @param delegate an object containing handler methods
	 * @throws IllegalStateException if no handler methods are found
	 */
	public final void setDelegate(Object delegate) {
		Assert.notNull(delegate, "Delegate must not be null");
		this.delegate = delegate;
		registerHandlerMethods(this.delegate);
		// There must be SOME handler methods.
		if (this.handlerMethodMap.isEmpty()) {
			throw new IllegalStateException("No handler methods in class [" + this.delegate.getClass() + "]");
		}
	}

	/**
	 * Set the method name resolver that this class should use.
	 * <p>Allows parameterization of handler method mappings.
	 */
	public final void setMethodNameResolver(MethodNameResolver methodNameResolver) {
		this.methodNameResolver = methodNameResolver;
	}

	/**
	 * Return the MethodNameResolver used by this class.
	 */
	public final MethodNameResolver getMethodNameResolver() {
		return this.methodNameResolver;
	}

	/**
	 * Set the {@link Validator Validators} for this controller.
	 * <p>The <code>Validators</code> must support the specified command class.
	 */
	public final void setValidators(Validator[] validators) {
		this.validators = validators;
	}

	/**
	 * Return the Validators for this controller.
	 */
	public final Validator[] getValidators() {
		return this.validators;
	}


	/**
	 * Registers all handlers methods on the delegate object.
	 */
	private void registerHandlerMethods(Object delegate) {
		this.handlerMethodMap.clear();
		this.lastModifiedMethodMap.clear();
		this.exceptionHandlerMap.clear();

		// Look at all methods in the subclass, trying to find
		// methods that are validators according to our criteria
		Method[] methods = delegate.getClass().getMethods();
		for (int i = 0; i < methods.length; i++) {
			// We're looking for methods with given parameters.
			Method method = methods[i];
			if (isExceptionHandlerMethod(method)) {
				registerExceptionHandlerMethod(method);
			}
			else if (isHandlerMethod(method)) {
				registerHandlerMethod(method);
				registerLastModifiedMethodIfExists(delegate, method);
			}
		}
	}

	/**
	 * Is the supplied method a valid handler method?
	 * <p>Does not consider <code>Controller.handleRequest</code> itself
	 * as handler method (to avoid potential stack overflow).
	 */
	private boolean isHandlerMethod(Method method) {
		Class returnType = method.getReturnType();
		if (ModelAndView.class.equals(returnType) || Map.class.equals(returnType) || void.class.equals(returnType)) {
			Class[] parameterTypes = method.getParameterTypes();
			return (parameterTypes.length >= 2 &&
					HttpServletRequest.class.equals(parameterTypes[0]) &&
					HttpServletResponse.class.equals(parameterTypes[1]) &&
					!("handleRequest".equals(method.getName()) && parameterTypes.length == 2));
		}
		return false;
	}

	/**
	 * Is the supplied method a valid exception handler method?
	 */
	private boolean isExceptionHandlerMethod(Method method) {
		return (isHandlerMethod(method) &&
				method.getParameterTypes().length == 3 &&
				Throwable.class.isAssignableFrom(method.getParameterTypes()[2]));
	}

	/**
	 * Registers the supplied method as a request handler.
	 */
	private void registerHandlerMethod(Method method) {
		if (logger.isDebugEnabled()) {
			logger.debug("Found action method [" + method + "]");
		}
		this.handlerMethodMap.put(method.getName(), method);
	}

	/**
	 * Registers a last-modified handler method for the supplied handler method
	 * if one exists.
	 */
	private void registerLastModifiedMethodIfExists(Object delegate, Method method) {
		// Look for corresponding LastModified method.
		try {
			Method lastModifiedMethod = delegate.getClass().getMethod(
					method.getName() + LAST_MODIFIED_METHOD_SUFFIX,
					new Class[] {HttpServletRequest.class});
			Class returnType = lastModifiedMethod.getReturnType();
			if (!(long.class.equals(returnType) || Long.class.equals(returnType))) {
				throw new IllegalStateException("last-modified method [" + lastModifiedMethod +
						"] declares an invalid return type - needs to be 'long' or 'Long'");
			}
			// Put in cache, keyed by handler method name.
			this.lastModifiedMethodMap.put(method.getName(), lastModifiedMethod);
			if (logger.isDebugEnabled()) {
				logger.debug("Found last-modified method for handler method [" + method + "]");
			}
		}
		catch (NoSuchMethodException ex) {
			// No last modified method. That's ok.
		}
	}

	/**
	 * Registers the supplied method as an exception handler.
	 */
	private void registerExceptionHandlerMethod(Method method) {
		this.exceptionHandlerMap.put(method.getParameterTypes()[2], method);