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Spring Framework example source code file (ModelAndView.java)

This example Spring Framework source code file (ModelAndView.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Java - Spring Framework tags/keywords

map, map, modelandview, modelandview, modelmap, object, object, string, string, stringbuffer, util, view

The Spring Framework ModelAndView.java source code

/*
 * Copyright 2002-2006 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.portlet;

import java.util.Map;

import org.springframework.ui.ModelMap;

/**
 * Holder for both Model and View in the web MVC framework.
 * Note that these are entirely distinct. This class merely holds
 * both to make it possible for a controller to return both model
 * and view in a single return value.
 *
 * <p>Represents a model and view returned by a handler, to be resolved
 * by a DispatcherPortlet. The view can take the form of a String
 * view name which will need to be resolved by a ViewResolver object;
 * alternatively a view object can be specified directly. The model
 * is a Map, allowing the use of multiple objects keyed by name.
 *
 * @author Juergen Hoeller
 * @since 2.0
 * @see org.springframework.web.portlet.DispatcherPortlet
 * @see org.springframework.web.servlet.ViewResolver
 * @see org.springframework.web.portlet.HandlerAdapter
 * @see org.springframework.web.portlet.mvc.Controller
 */
public class ModelAndView {

	/** View instance or view name String */
	private Object view;

	/** Model Map */
	private ModelMap model;

	/**
	 * Indicates whether or not this instance has been cleared with a call to {@link #clear()}.
	 */
	private boolean cleared;


	/**
	 * Default constructor for bean-style usage: populating bean
	 * properties instead of passing in constructor arguments.
	 * @see #setView(Object)
	 * @see #setViewName(String)
	 */
	public ModelAndView() {
	}

	/**
	 * Convenient constructor when there is no model data to expose.
	 * Can also be used in conjunction with <code>addObject.
	 * @param viewName name of the View to render, to be resolved
	 * by the DispatcherPortlet's ViewResolver
	 * @see #addObject
	 */
	public ModelAndView(String viewName) {
		this.view = viewName;
	}

	/**
	 * Convenient constructor when there is no model data to expose.
	 * Can also be used in conjunction with <code>addObject.
	 * @param view View object to render (usually a Servlet MVC View object)
	 * @see #addObject
	 */
	public ModelAndView(Object view) {
		this.view = view;
	}

	/**
	 * Create a new ModelAndView given a view name and a model.
	 * @param viewName name of the View to render, to be resolved
	 * by the DispatcherPortlet's ViewResolver
	 * @param model Map of model names (Strings) to model objects
	 * (Objects). Model entries may not be <code>null, but the
	 * model Map may be <code>null if there is no model data.
	 */
	public ModelAndView(String viewName, Map model) {
		this.view = viewName;
		if (model != null) {
			getModelMap().addAllAttributes(model);
		}
	}

	/**
	 * Create a new ModelAndView given a View object and a model.
	 * @param view View object to render (usually a Servlet MVC View object)
	 * @param model Map of model names (Strings) to model objects
	 * (Objects). Model entries may not be <code>null, but the
	 * model Map may be <code>null if there is no model data.
	 */
	public ModelAndView(Object view, Map model) {
		this.view = view;
		if (model != null) {
			getModelMap().addAllAttributes(model);
		}
	}

	/**
	 * Convenient constructor to take a single model object.
	 * @param viewName name of the View to render, to be resolved
	 * by the DispatcherPortlet's ViewResolver
	 * @param modelName name of the single entry in the model
	 * @param modelObject the single model object
	 */
	public ModelAndView(String viewName, String modelName, Object modelObject) {
		this.view = viewName;
		addObject(modelName, modelObject);
	}

	/**
	 * Convenient constructor to take a single model object.
	 * @param view View object to render (usually a Servlet MVC View object)
	 * @param modelName name of the single entry in the model
	 * @param modelObject the single model object
	 */
	public ModelAndView(Object view, String modelName, Object modelObject) {
		this.view = view;
		addObject(modelName, modelObject);
	}


	/**
	 * Set a view name for this ModelAndView, to be resolved by the
	 * DispatcherPortlet via a ViewResolver. Will override any
	 * pre-existing view name or View.
	 */
	public void setViewName(String viewName) {
		this.view = viewName;
	}

	/**
	 * Return the view name to be resolved by the DispatcherPortlet
	 * via a ViewResolver, or <code>null if we are using a view object.
	 */
	public String getViewName() {
		return (this.view instanceof String ? (String) this.view : null);
	}

	/**
	 * Set a View object for this ModelAndView. Will override any
	 * pre-existing view name or View.
	 * <p>The given View object will usually be a Servlet MVC View object.
	 * This is nevertheless typed as Object to avoid a Servlet API dependency
	 * in the Portlet ModelAndView class.
	 */
	public void setView(Object view) {
		this.view = view;
	}

	/**
	 * Return the View object, or <code>null if we are using a view name
	 * to be resolved by the DispatcherPortlet via a ViewResolver.
	 */
	public Object getView() {
		return (!(this.view instanceof String) ? this.view : null);
	}

	/**
	 * Indicate whether or not this <code>ModelAndView has a view, either
	 * as a view name or as a direct view instance.
	 */
	public boolean hasView() {
		return (this.view != null);
	}

	/**
	 * Return whether we use a view reference, i.e. <code>true
	 * if the view has been specified via a name to be resolved by the
	 * DispatcherPortlet via a ViewResolver.
	 */
	public boolean isReference() {
		return (this.view instanceof String);
	}

	/**
	 * Return the model map. May return <code>null.
	 * Called by DispatcherPortlet for evaluation of the model.
	 */
	protected Map getModelInternal() {
		return this.model;
	}

	/**
	 * Return the underlying <code>ModelMap instance (never null).
	 */
	public ModelMap getModelMap() {
		if (this.model == null) {
			this.model = new ModelMap();
		}
		return this.model;
	}

	/**
	 * Return the model map. Never returns <code>null.
	 * To be called by application code for modifying the model.
	 */
	public Map getModel() {
		return getModelMap();
	}


	/**
	 * Add an attribute to the model.
	 * @param attributeName name of the object to add to the model
	 * @param attributeValue object to add to the model (never <code>null)
	 * @see ModelMap#addAttribute(String, Object)
	 * @see #getModelMap()
	 */
	public ModelAndView addObject(String attributeName, Object attributeValue) {
		getModelMap().addAttribute(attributeName, attributeValue);
		return this;
	}

	/**
	 * Add an attribute to the model using parameter name generation.
	 * @param attributeValue the object to add to the model (never <code>null)
	 * @see ModelMap#addAttribute(Object)
	 * @see #getModelMap()
	 */
	public ModelAndView addObject(Object attributeValue) {
		getModelMap().addAttribute(attributeValue);
		return this;
	}

	/**
	 * Add all attributes contained in the provided Map to the model.
	 * @param modelMap a Map of attributeName -> attributeValue pairs
	 * @see ModelMap#addAllAttributes(Map)
	 * @see #getModelMap()
	 */
	public ModelAndView addAllObjects(Map modelMap) {
		getModelMap().addAllAttributes(modelMap);
		return this;
	}


	/**
	 * Clear the state of this ModelAndView object.
	 * The object will be empty afterwards.
	 * <p>Can be used to suppress rendering of a given ModelAndView object
	 * in the <code>postHandleRender method of a HandlerInterceptor.
	 * @see #isEmpty()
	 * @see HandlerInterceptor#postHandleRender
	 */
	public void clear() {
		this.view = null;
		this.model = null;
		this.cleared = true;
	}

	/**
	 * Return whether this ModelAndView object is empty
	 * i.e. whether it does not hold any view and does not contain a model.
	 */
	public boolean isEmpty() {
		return (this.view == null && this.model == null);
	}

	/**
	 * Return whether this ModelAndView object is empty as a result of a call to {@link #clear}
	 * i.e. whether it does not hold any view and does not contain a model.
	 * Returns <code>false if any additional state was added to the instance
	 * <strong>after the call to {@link #clear}.
	 * @see #clear()
	 */
	public boolean wasCleared() {
		return (this.cleared && isEmpty());
	}


	/**
	 * Return diagnostic information about this model and view.
	 */
	public String toString() {
		StringBuffer buf = new StringBuffer("ModelAndView: ");
		if (isReference()) {
			buf.append("reference to view with name '").append(this.view).append("'");
		}
		else {
			buf.append("materialized View is [").append(this.view).append(']');
		}
		buf.append("; model is ").append(this.model);
		return buf.toString();
	}

}

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