001/* 002 Licensed to the Apache Software Foundation (ASF) under one 003 or more contributor license agreements. See the NOTICE file 004 distributed with this work for additional information 005 regarding copyright ownership. The ASF licenses this file 006 to you under the Apache License, Version 2.0 (the 007 "License"); you may not use this file except in compliance 008 with the License. You may obtain a copy of the License at 009 010 http://www.apache.org/licenses/LICENSE-2.0 011 012 Unless required by applicable law or agreed to in writing, 013 software distributed under the License is distributed on an 014 "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 015 KIND, either express or implied. See the License for the 016 specific language governing permissions and limitations 017 under the License. 018 */ 019package org.apache.wiki.api.filters; 020 021import org.apache.wiki.api.core.Context; 022import org.apache.wiki.api.core.Engine; 023import org.apache.wiki.api.exceptions.FilterException; 024 025import java.lang.reflect.Method; 026import java.util.Properties; 027 028import static org.apache.wiki.api.filters.FilterSupportOperations.executePageFilterPhase; 029import static org.apache.wiki.api.filters.FilterSupportOperations.methodOfNonPublicAPI; 030 031 032/** 033 * <p>Provides a definition for a page filter. A page filter is a class that can be used to transform the WikiPage content being saved or 034 * being loaded at any given time.</p> 035 * <p>Note that the Context#getPage() method always returns the context in which text is rendered, i.e. the original request. Thus the 036 * content may actually be different content than what what the Context#getPage() implies! This happens often if you are for example 037 * including multiple pages on the same page.</p> 038 * <p>PageFilters must be thread-safe! There is only one instance of each PageFilter per each Engine invocation. If you need to store data 039 * persistently, use VariableManager, or WikiContext.</p> 040 * <p><strong>Design notes</strong></p> 041 * <p>As of 2.5.30, initialize() gains access to the Engine.</p> 042 * <p>As of 2.11.0.M7, almost all methods from BasicPageFilter end up here as default methods.</p> 043 * <p>In order to preserve backwards compatibility with filters not using the public API, these default methods checks if a given filter 044 * is using the old, non public API and, if that's the case attempt to execute the old, non public api corresponding method. If the filter 045 * uses the public API, then the default callback is used. None of the default callbacks do anything, so it is a good idea for you to 046 * implement only methods that you need.</p> 047 */ 048public interface PageFilter { 049 050 /** 051 * Is called whenever the a new PageFilter is instantiated and reset. 052 * 053 * @param engine The Engine which owns this PageFilter 054 * @param properties The properties ripped from filters.xml. 055 * @throws FilterException If the filter could not be initialized. If this is thrown, the filter is not added to the internal queues. 056 */ 057 void initialize( Engine engine, Properties properties ) throws FilterException; 058 059 /** 060 * This method is called whenever a page has been loaded from the provider, but not yet been sent through the markup-translation 061 * process. Note that you cannot do HTML translation here, because it will be escaped. 062 * 063 * @param context The current context. 064 * @param content WikiMarkup. 065 * @return The modified wikimarkup content. Default implementation returns the markup as received. 066 * @throws FilterException If something goes wrong. Throwing this causes the entire page processing to be abandoned. 067 */ 068 default String preTranslate( final Context context, final String content ) throws FilterException { 069 final Method m = methodOfNonPublicAPI( this, "preTranslate", "org.apache.wiki.WikiContext", "java.lang.String" ); 070 return executePageFilterPhase( () -> content, m, this, context, content ); 071 // return content; 072 } 073 074 /** 075 * This method is called after a page has been fed through the translation process, so anything you are seeing here is translated 076 * content. If you want to do any of your own WikiMarkup2HTML translation, do it here. 077 * 078 * @param context The WikiContext. 079 * @param htmlContent The translated HTML. 080 * @return The modified HTML. Default implementation returns the translated html as received. 081 * @throws FilterException If something goes wrong. Throwing this causes the entire page processing to be abandoned. 082 */ 083 default String postTranslate( final Context context, final String htmlContent ) throws FilterException { 084 final Method m = methodOfNonPublicAPI( this, "postTranslate", "org.apache.wiki.WikiContext", "java.lang.String" ); 085 return executePageFilterPhase( () -> htmlContent, m, this, context, htmlContent ); 086 // return htmlContent; 087 } 088 089 /** 090 * This method is called before the page has been saved to the PageProvider. 091 * 092 * @param context The WikiContext 093 * @param content The wikimarkup that the user just wanted to save. 094 * @return The modified wikimarkup. Default implementation returns the markup as received. 095 * @throws FilterException If something goes wrong. Throwing this causes the entire page processing to be abandoned. 096 */ 097 default String preSave( final Context context, final String content ) throws FilterException { 098 final Method m = methodOfNonPublicAPI( this, "preSave", "org.apache.wiki.WikiContext", "java.lang.String" ); 099 return executePageFilterPhase( () -> content, m, this, context, content ); 100 // return content; 101 } 102 103 /** 104 * This method is called after the page has been successfully saved. If the saving fails for any reason, then this method will not 105 * be called. 106 * <p> 107 * Since the result is discarded from this method, this is only useful for things like counters, etc. 108 * 109 * @param context The WikiContext 110 * @param content The content which was just stored. 111 * @throws FilterException If something goes wrong. As the page is already saved, This is just logged. 112 */ 113 default void postSave( final Context context, final String content ) throws FilterException { 114 final Method m = methodOfNonPublicAPI( this, "postSave", "org.apache.wiki.WikiContext", "java.lang.String" ); 115 executePageFilterPhase( () -> null, m, this, content ); 116 // empty method 117 } 118 119 /** 120 * Called for every filter, e.g. on wiki engine shutdown. Use this if you have to 121 * clean up or close global resources you allocated in the initialize() method. 122 * 123 * @param engine The Engine which owns this filter. 124 * @since 2.5.36 125 */ 126 default void destroy( final Engine engine ) { 127 final Method m = methodOfNonPublicAPI( this, "destroy", "org.apache.wiki.WikiEngine" ); 128 executePageFilterPhase( () -> null, m, this, engine ); 129 // empty method 130 } 131 132}