/*
* 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.servlet;
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 DispatcherServlet. 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 Rod Johnson
* @author Juergen Hoeller
* @author Rob Harrop
* @see DispatcherServlet
* @see ViewResolver
* @see HandlerAdapter#handle
* @see org.springframework.web.servlet.mvc.Controller#handleRequest
*/
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(View)
* @see #setViewName(String)
*/
public ModelAndView() {
}
/**
* Convenient constructor when there is no model data to expose.
* Can also be used in conjunction with <code>addObject</code>.
* @param viewName name of the View to render, to be resolved
* by the DispatcherServlet'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</code>.
* @param view View object to render
* @see #addObject
*/
public ModelAndView(View view) {
this.view = view;
}
/**
* Creates new ModelAndView given a view name and a model.
* @param viewName name of the View to render, to be resolved
* by the DispatcherServlet's ViewResolver
* @param model Map of model names (Strings) to model objects
* (Objects). Model entries may not be <code>null</code>, but the
* model Map may be <code>null</code> if there is no model data.
*/
public ModelAndView(String viewName, Map model) {
this.view = viewName;
if (model != null) {
getModelMap().addAllAttributes(model);
}
}
/**
* Creates new ModelAndView given a View object and a model.
* <emphasis>Note: the supplied model data is copied into the internal
* storage of this class. You should not consider to modify the supplied
* Map after supplying it to this class</emphasis>
* @param view View object to render
* @param model Map of model names (Strings) to model objects
* (Objects). Model entries may not be <code>null</code>, but the
* model Map may be <code>null</code> if there is no model data.
*/
public ModelAndView(View 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 DispatcherServlet'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
* @param modelName name of the single entry in the model
* @param modelObject the single model object
*/
public ModelAndView(View view, String modelName, Object modelObject) {
this.view = view;
addObject(modelName, modelObject);
}
/**
* Set a view name for this ModelAndView, to be resolved by the
* DispatcherServlet 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 DispatcherServlet
* via a ViewResolver, or <code>null</code> 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.
*/
public void setView(View view) {
this.view = view;
}
/**
* Return the View object, or <code>null</code> if we are using a view name
* to be resolved by the DispatcherServlet via a ViewResolver.
*/
public View getView() {
return (this.view instanceof View ? (View) this.view : null);
}
/**
* Indicate whether or not this <code>ModelAndView</code> has a view, either
* as a view name or as a direct {@link View} instance.
*/
public boolean hasView() {
return (this.view != null);
}
/**
* Return whether we use a view reference, i.e. <code>true</code>
* if the view has been specified via a name to be resolved by the
* DispatcherServlet via a ViewResolver.
*/
public boolean isReference() {
return (this.view instanceof String);
}
/**
* Return the model map. May return <code>null</code>.
* Called by DispatcherServlet for evaluation of the model.
*/
protected Map getModelInternal() {
return this.model;
}
/**
* Return the underlying <code>ModelMap</code> instance (never <code>null</code>).
*/
public ModelMap getModelMap() {
if (this.model == null) {
this.model = new ModelMap();
}
return this.model;
}
/**
* Return the model map. Never returns <code>null</code>.
* 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</code>)
* @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</code>)
* @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>postHandle</code> method of a HandlerInterceptor.
* @see #isEmpty()
* @see HandlerInterceptor#postHandle
*/
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</code> if any additional state was added to the instance
* <strong>after</strong> 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();
}
}