1 /* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, 13 * software distributed under the License is distributed on an 14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 15 * KIND, either express or implied. See the License for the 16 * specific language governing permissions and limitations 17 * under the License. 18 * 19 */ 20 package org.apache.mina.session; 21 22 import java.util.Collections; 23 import java.util.Set; 24 25 /** 26 * An interface exposing the getters and setters on Attributes 27 * 28 * @author <a href="http://mina.apache.org">Apache MINA Project</a> 29 */ 30 interface AttributeContainer { 31 /** 32 * Returns the value of the user-defined attribute for the given 33 * <code>key</code>. 34 * 35 * @param key 36 * the attribute's key, must not be <code>null</code> 37 * @return <tt>null</tt> if there is no attribute with the specified key 38 * @exception IllegalArgumentException 39 * if <code>key==null</code> 40 * @see #setAttribute(AttributeKey, Object) 41 */ 42 <T> T getAttribute(AttributeKey<T> key); 43 44 /** 45 * Returns the value of the user-defined attribute for the given 46 * <code>key</code>. 47 * 48 * @param key 49 * the attribute's key, must not be <code>null</code> 50 * @return <tt>null</tt> if there is no attribute with the specified key 51 * @exception IllegalArgumentException 52 * if <code>key==null</code> 53 * @see #setAttribute(AttributeKey, Object) 54 */ 55 <T> T getAttribute(AttributeKey<T> key, T value); 56 57 /** 58 * Removes the specified Attribute from this container. The old value will 59 * be returned, <code>null</code> will be returned if there is no such 60 * attribute in this container.<br> 61 * <br> 62 * This method is equivalent to <code>setAttribute(key,null)</code>. 63 * 64 * @param key 65 * of the attribute to be removed,must not be <code>null</code> 66 * @return the removed value, <code>null</code> if this container doesn't 67 * contain the specified attribute 68 * @exception IllegalArgumentException 69 * if <code>key==null</code> 70 */ 71 <T> T removeAttribute(AttributeKey<T> key); 72 73 /** 74 * Sets a user-defined attribute. If the <code>value</code> is 75 * <code>null</code> the attribute will be removed from this container. 76 * 77 * @param key 78 * the attribute's key, must not be <code>null</code> 79 * @param value 80 * the attribute's value, <code>null</code> to remove the 81 * attribute 82 * @return The old attribute's value. <code>null</code> if there is no 83 * previous value or if the value is <code>null</code> 84 * @exception IllegalArgumentException 85 * if {@code value!=null} and not an instance of type that is 86 * specified in the key (see {@link AttributeKey#getType()}) 87 * 88 * @see #getAttribute(AttributeKey) 89 */ 90 <T> T setAttribute(AttributeKey<? extends T> key, T value); 91 92 /** 93 * Returns an unmodifiable {@link Set} including all Keys of this container. If 94 * this container contains no key's an empty {@link Set} will be returned. 95 * 96 * @return all Keys, never <code>null</code> 97 * @see Collections#unmodifiableSet(Set) 98 */ 99 Set<AttributeKey<?>> getAttributeKeys(); 100 }