001/* 002 * Copyright 2002-2017 the original author or authors. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * https://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package org.springframework.web.servlet.view; 018 019import java.util.Locale; 020 021import org.springframework.beans.factory.InitializingBean; 022import org.springframework.lang.Nullable; 023 024/** 025 * Abstract base class for URL-based views. Provides a consistent way of 026 * holding the URL that a View wraps, in the form of a "url" bean property. 027 * 028 * @author Juergen Hoeller 029 * @since 13.12.2003 030 */ 031public abstract class AbstractUrlBasedView extends AbstractView implements InitializingBean { 032 033 @Nullable 034 private String url; 035 036 037 /** 038 * Constructor for use as a bean. 039 */ 040 protected AbstractUrlBasedView() { 041 } 042 043 /** 044 * Create a new AbstractUrlBasedView with the given URL. 045 * @param url the URL to forward to 046 */ 047 protected AbstractUrlBasedView(String url) { 048 this.url = url; 049 } 050 051 052 /** 053 * Set the URL of the resource that this view wraps. 054 * The URL must be appropriate for the concrete View implementation. 055 */ 056 public void setUrl(@Nullable String url) { 057 this.url = url; 058 } 059 060 /** 061 * Return the URL of the resource that this view wraps. 062 */ 063 @Nullable 064 public String getUrl() { 065 return this.url; 066 } 067 068 @Override 069 public void afterPropertiesSet() throws Exception { 070 if (isUrlRequired() && getUrl() == null) { 071 throw new IllegalArgumentException("Property 'url' is required"); 072 } 073 } 074 075 /** 076 * Return whether the 'url' property is required. 077 * <p>The default implementation returns {@code true}. 078 * This can be overridden in subclasses. 079 */ 080 protected boolean isUrlRequired() { 081 return true; 082 } 083 084 /** 085 * Check whether the underlying resource that the configured URL points to 086 * actually exists. 087 * @param locale the desired Locale that we're looking for 088 * @return {@code true} if the resource exists (or is assumed to exist); 089 * {@code false} if we know that it does not exist 090 * @throws Exception if the resource exists but is invalid (e.g. could not be parsed) 091 */ 092 public boolean checkResource(Locale locale) throws Exception { 093 return true; 094 } 095 096 @Override 097 public String toString() { 098 return super.toString() + "; URL [" + getUrl() + "]"; 099 } 100 101}