Java tutorial
/* * Copyright 2002-2017 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.mvc; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.springframework.http.HttpMethod; import org.springframework.http.HttpStatus; import org.springframework.lang.Nullable; import org.springframework.web.servlet.ModelAndView; import org.springframework.web.servlet.View; import org.springframework.web.servlet.support.RequestContextUtils; /** * Trivial controller that always returns a pre-configured view and optionally * sets the response status code. The view and status can be configured using * the provided configuration properties. * * @author Rod Johnson * @author Juergen Hoeller * @author Keith Donald * @author Rossen Stoyanchev */ public class ParameterizableViewController extends AbstractController { @Nullable private Object view; @Nullable private HttpStatus statusCode; private boolean statusOnly; public ParameterizableViewController() { super(false); setSupportedMethods(HttpMethod.GET.name(), HttpMethod.HEAD.name()); } /** * Set a view name for the ModelAndView to return, to be resolved by the * DispatcherServlet via a ViewResolver. Will override any pre-existing * view name or View. */ public void setViewName(@Nullable String viewName) { this.view = viewName; } /** * Return the name of the view to delegate to, or {@code null} if using a * View instance. */ @Nullable public String getViewName() { if (this.view instanceof String) { String viewName = (String) this.view; if (getStatusCode() != null && getStatusCode().is3xxRedirection()) { return viewName.startsWith("redirect:") ? viewName : "redirect:" + viewName; } else { return viewName; } } return null; } /** * Set a View object for the ModelAndView to return. * Will override any pre-existing view name or View. * @since 4.1 */ public void setView(View view) { this.view = view; } /** * Return the View object, or {@code null} if we are using a view name * to be resolved by the DispatcherServlet via a ViewResolver. * @since 4.1 */ @Nullable public View getView() { return (this.view instanceof View ? (View) this.view : null); } /** * Configure the HTTP status code that this controller should set on the * response. * <p>When a "redirect:" prefixed view name is configured, there is no need * to set this property since RedirectView will do that. However this property * may still be used to override the 3xx status code of {@code RedirectView}. * For full control over redirecting provide a {@code RedirectView} instance. * <p>If the status code is 204 and no view is configured, the request is * fully handled within the controller. * @since 4.1 */ public void setStatusCode(@Nullable HttpStatus statusCode) { this.statusCode = statusCode; } /** * Return the configured HTTP status code or {@code null}. * @since 4.1 */ @Nullable public HttpStatus getStatusCode() { return this.statusCode; } /** * The property can be used to indicate the request is considered fully * handled within the controller and that no view should be used for rendering. * Useful in combination with {@link #setStatusCode}. * <p>By default this is set to {@code false}. * @since 4.1 */ public void setStatusOnly(boolean statusOnly) { this.statusOnly = statusOnly; } /** * Whether the request is fully handled within the controller. */ public boolean isStatusOnly() { return this.statusOnly; } /** * Return a ModelAndView object with the specified view name. * <p>The content of the {@link RequestContextUtils#getInputFlashMap * "input" FlashMap} is also added to the model. * @see #getViewName() */ @Override protected ModelAndView handleRequestInternal(HttpServletRequest request, HttpServletResponse response) throws Exception { String viewName = getViewName(); if (getStatusCode() != null) { if (getStatusCode().is3xxRedirection()) { request.setAttribute(View.RESPONSE_STATUS_ATTRIBUTE, getStatusCode()); } else { response.setStatus(getStatusCode().value()); if (getStatusCode().equals(HttpStatus.NO_CONTENT) && viewName == null) { return null; } } } if (isStatusOnly()) { return null; } ModelAndView modelAndView = new ModelAndView(); modelAndView.addAllObjects(RequestContextUtils.getInputFlashMap(request)); if (viewName != null) { modelAndView.setViewName(viewName); } else { modelAndView.setView(getView()); } return modelAndView; } @Override public String toString() { return "ParameterizableViewController [" + formatStatusAndView() + "]"; } private String formatStatusAndView() { StringBuilder sb = new StringBuilder(); if (this.statusCode != null) { sb.append("status=").append(this.statusCode); } if (this.view != null) { sb.append(sb.length() != 0 ? ", " : ""); String viewName = getViewName(); sb.append("view=").append(viewName != null ? "\"" + viewName + "\"" : this.view); } return sb.toString(); } }