org.springframework.web.servlet.View Maven / Gradle / Ivy
/*
* Copyright 2002-2018 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
*
* https://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 jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.springframework.lang.Nullable;
/**
* MVC View for a web interaction. Implementations are responsible for rendering
* content, and exposing the model. A single view exposes multiple model attributes.
*
* This class and the MVC approach associated with it is discussed in Chapter 12 of
* Expert One-On-One J2EE Design and Development
* by Rod Johnson (Wrox, 2002).
*
*
View implementations may differ widely. An obvious implementation would be
* JSP-based. Other implementations might be XSLT-based, or use an HTML generation library.
* This interface is designed to avoid restricting the range of possible implementations.
*
*
Views should be beans. They are likely to be instantiated as beans by a ViewResolver.
* As this interface is stateless, view implementations should be thread-safe.
*
* @author Rod Johnson
* @author Arjen Poutsma
* @author Rossen Stoyanchev
* @see org.springframework.web.servlet.view.AbstractView
* @see org.springframework.web.servlet.view.InternalResourceView
*/
public interface View {
/**
* Name of the {@link HttpServletRequest} attribute that contains the response status code.
*
Note: This attribute is not required to be supported by all View implementations.
* @since 3.0
*/
String RESPONSE_STATUS_ATTRIBUTE = View.class.getName() + ".responseStatus";
/**
* Name of the {@link HttpServletRequest} attribute that contains a Map with path variables.
* The map consists of String-based URI template variable names as keys and their corresponding
* Object-based values -- extracted from segments of the URL and type converted.
*
Note: This attribute is not required to be supported by all View implementations.
* @since 3.1
*/
String PATH_VARIABLES = View.class.getName() + ".pathVariables";
/**
* The {@link org.springframework.http.MediaType} selected during content negotiation,
* which may be more specific than the one the View is configured with. For example:
* "application/vnd.example-v1+xml" vs "application/*+xml".
* @since 3.2
*/
String SELECTED_CONTENT_TYPE = View.class.getName() + ".selectedContentType";
/**
* Return the content type of the view, if predetermined.
*
Can be used to check the view's content type upfront,
* i.e. before an actual rendering attempt.
* @return the content type String (optionally including a character set),
* or {@code null} if not predetermined
*/
@Nullable
default String getContentType() {
return null;
}
/**
* Render the view given the specified model.
*
The first step will be preparing the request: In the JSP case, this would mean
* setting model objects as request attributes. The second step will be the actual
* rendering of the view, for example including the JSP via a RequestDispatcher.
* @param model a Map with name Strings as keys and corresponding model
* objects as values (Map can also be {@code null} in case of empty model)
* @param request current HTTP request
* @param response he HTTP response we are building
* @throws Exception if rendering failed
*/
void render(@Nullable Map model, HttpServletRequest request, HttpServletResponse response)
throws Exception;
}