org.springframework.web.servlet.ModelAndView Maven / Gradle / Ivy
/*
* 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;
import java.util.HashMap;
import java.util.Map;
/**
* 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.
*
* Class to represent a model and view returned by a handler used
* by a DispatcherServlet. The view can take the form of a reference
* to a View object, or a String view name which will need to be
* resolved by a ViewResolver object. The model is a Map, allowing
* the use of multiple data objects keyed by name.
*
* @author Rod Johnson
* @author Juergen Hoeller
* @see DispatcherServlet
* @see ViewResolver
* @see HandlerAdapter#handle
* @see org.springframework.web.servlet.mvc.Controller#handleRequest
*/
public class ModelAndView {
/** View if we hold an object reference */
private View view;
/**
* View name if we hold a view name that will be resolved
* by the DispatcherServlet via a ViewResolver
*/
private String viewName;
/** Model */
private Map model;
/**
* 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 addObject.
* @param view View object to render
* @see #addObject
*/
public ModelAndView(View view) {
this.view = view;
}
/**
* Convenient constructor when there is no model data to expose.
* Can also be used in conjunction with addObject.
* @param viewName name of the View to render, to be resolved
* by the DispatcherServlet
* @see #addObject
*/
public ModelAndView(String viewName) {
this.viewName = viewName;
}
/**
* Creates new ModelAndView given a View object and a model.
* @param view View object to render
* @param model Map of model names (Strings) to model objects
* (Objects). Model entries may not be null, but the model Map
* may be null if there is no model data.
*/
public ModelAndView(View view, Map model) {
this.view = view;
this.model = model;
}
/**
* Creates new ModelAndView given a view name and a model.
* @param viewName name of the View to render, to be resolved
* by the DispatcherServlet
* @param model Map of model names (Strings) to model objects
* (Objects). Model entries may not be null, but the model Map
* may be null if there is no model data.
*/
public ModelAndView(String viewName, Map model) {
this.viewName = viewName;
this.model = model;
}
/**
* 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);
}
/**
* Convenient constructor to take a single model object.
* @param viewName name of the View to render, to be resolved
* by the DispatcherServlet
* @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.viewName = viewName;
addObject(modelName, modelObject);
}
/**
* Set a View object for this ModelAndView. Will override any
* pre-existing view name or View.
*/
public void setView(View view) {
this.view = view;
this.viewName = null;
}
/**
* Return the View object, or null if we are using a view name
* to be resolved by the DispatcherServlet via a ViewResolver.
*/
public View getView() {
return view;
}
/**
* 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.viewName = viewName;
this.view = null;
}
/**
* Return the view name to be resolved by the DispatcherServlet
* via a ViewResolver, or null if we are using a View object.
*/
public String getViewName() {
return viewName;
}
/**
* Return whether we use a view reference, i.e. true if the
* view has been specified via a name to be resolved by the
* DispatcherServlet via a ViewResolver.
*/
public boolean isReference() {
return (this.viewName != null);
}
/**
* Return the model map. May return null.
* Called by DispatcherServlet for evaluation of the model.
*/
protected Map getModelInternal() {
return this.model;
}
/**
* Return the model map. Never returns null.
* To be called by application code for modifying the model.
*/
public Map getModel() {
if (this.model == null) {
this.model = new HashMap(1);
}
return this.model;
}
/**
* Add an object to the model.
* @param modelName name of the object to add to the model
* @param modelObject object to add to the model. May not be null.
* @return this ModelAndView, convenient to allow usages like
* return modelAndView.addObject("foo", bar);
*/
public ModelAndView addObject(String modelName, Object modelObject) {
getModel().put(modelName, modelObject);
return this;
}
/**
* Add all entries contained in the provided map to the model.
* @param modelMap a map of modelName->modelObject pairs
* @return this ModelAndView, convenient to allow usages like
* return modelAndView.addAllObjects(myModelMap);
*/
public ModelAndView addAllObjects(Map modelMap) {
getModel().putAll(modelMap);
return this;
}
/**
* Clear the state of this ModelAndView object.
* The object will be empty afterwards.
*
Can be used to suppress rendering of a given ModelAndView object
* in the postHandle method of a HandlerInterceptor.
* @see #isEmpty
* @see HandlerInterceptor#postHandle
*/
public void clear() {
this.view = null;
this.viewName = null;
this.model = null;
}
/**
* Return whether this ModelAndView object is empty,
* i.e. whether it does not hold any view and does not contain a model.
* @see #clear
*/
public boolean isEmpty() {
return (this.view == null && this.viewName == null && this.model == null);
}
/**
* 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.viewName).append("'");
}
else {
buf.append("materialized View is [").append(this.view).append(']');
}
buf.append("; model is ").append(this.model);
return buf.toString();
}
}