| 1 | package org.apache.velocity; |
| 2 | |
| 3 | /* |
| 4 | * Copyright 2000-2001,2004 The Apache Software Foundation. |
| 5 | * |
| 6 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 7 | * you may not use this file except in compliance with the License. |
| 8 | * 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, software |
| 13 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 15 | * See the License for the specific language governing permissions and |
| 16 | * limitations under the License. |
| 17 | */ |
| 18 | |
| 19 | import java.util.HashMap; |
| 20 | import java.util.Map; |
| 21 | |
| 22 | import org.apache.velocity.context.AbstractContext; |
| 23 | import org.apache.velocity.context.Context; |
| 24 | |
| 25 | /** |
| 26 | * General purpose implemention of the application Context |
| 27 | * interface for general application use. This class should |
| 28 | * be used in place of the original Context class. |
| 29 | * |
| 30 | * This implementation uses a HashMap (@see java.util.HashMap ) |
| 31 | * for data storage. |
| 32 | * |
| 33 | * This context implementation cannot be shared between threads |
| 34 | * without those threads synchronizing access between them, as |
| 35 | * the HashMap is not synchronized, nor are some of the fundamentals |
| 36 | * of AbstractContext. If you need to share a Context between |
| 37 | * threads with simultaneous access for some reason, please create |
| 38 | * your own and extend the interface Context |
| 39 | * |
| 40 | * @see org.apache.velocity.context.Context |
| 41 | * |
| 42 | * @author <a href="mailto:geirm@optonline.net">Geir Magnusson Jr.</a> |
| 43 | * @author <a href="mailto:jvanzyl@apache.org">Jason van Zyl</a> |
| 44 | * @author <a href="mailto:fedor.karpelevitch@home.com">Fedor Karpelevitch</a> |
| 45 | * @author <a href="mailto:dlr@finemaltcoding.com">Daniel Rall</a> |
| 46 | * @version $Id: VelocityContext.java,v 1.6.8.1 2004/03/03 22:27:36 geirm Exp $ |
| 47 | */ |
| 48 | public class VelocityContext extends AbstractContext implements Cloneable |
| 49 | { |
| 50 | /** |
| 51 | * Storage for key/value pairs. |
| 52 | */ |
| 53 | private Map context = null; |
| 54 | |
| 55 | /** |
| 56 | * Creates a new instance (with no inner context). |
| 57 | */ |
| 58 | public VelocityContext() |
| 59 | { |
| 60 | this(null, null); |
| 61 | } |
| 62 | |
| 63 | /** |
| 64 | * Creates a new instance with the provided storage (and no inner |
| 65 | * context). |
| 66 | */ |
| 67 | public VelocityContext(Map context) |
| 68 | { |
| 69 | this(context, null); |
| 70 | } |
| 71 | |
| 72 | /** |
| 73 | * Chaining constructor, used when you want to |
| 74 | * wrap a context in another. The inner context |
| 75 | * will be 'read only' - put() calls to the |
| 76 | * wrapping context will only effect the outermost |
| 77 | * context |
| 78 | * |
| 79 | * @param innerContext The <code>Context</code> implementation to |
| 80 | * wrap. |
| 81 | */ |
| 82 | public VelocityContext( Context innerContext ) |
| 83 | { |
| 84 | this(null, innerContext); |
| 85 | } |
| 86 | |
| 87 | /** |
| 88 | * Initializes internal storage (never to <code>null</code>), and |
| 89 | * inner context. |
| 90 | * |
| 91 | * @param context Internal storage, or <code>null</code> to |
| 92 | * create default storage. |
| 93 | * @param innerContext Inner context. |
| 94 | */ |
| 95 | public VelocityContext(Map context, Context innerContext) |
| 96 | { |
| 97 | super(innerContext); |
| 98 | this.context = (context == null ? new HashMap() : context); |
| 99 | } |
| 100 | |
| 101 | /** |
| 102 | * retrieves value for key from internal |
| 103 | * storage |
| 104 | * |
| 105 | * @param key name of value to get |
| 106 | * @return value as object |
| 107 | */ |
| 108 | public Object internalGet( String key ) |
| 109 | { |
| 110 | return context.get( key ); |
| 111 | } |
| 112 | |
| 113 | /** |
| 114 | * stores the value for key to internal |
| 115 | * storage |
| 116 | * |
| 117 | * @param key name of value to store |
| 118 | * @param value value to store |
| 119 | * @return previous value of key as Object |
| 120 | */ |
| 121 | public Object internalPut( String key, Object value ) |
| 122 | { |
| 123 | return context.put( key, value ); |
| 124 | } |
| 125 | |
| 126 | /** |
| 127 | * determines if there is a value for the |
| 128 | * given key |
| 129 | * |
| 130 | * @param key name of value to check |
| 131 | * @return true if non-null value in store |
| 132 | */ |
| 133 | public boolean internalContainsKey(Object key) |
| 134 | { |
| 135 | return context.containsKey( key ); |
| 136 | } |
| 137 | |
| 138 | /** |
| 139 | * returns array of keys |
| 140 | * |
| 141 | * @return keys as [] |
| 142 | */ |
| 143 | public Object[] internalGetKeys() |
| 144 | { |
| 145 | return context.keySet().toArray(); |
| 146 | } |
| 147 | |
| 148 | /** |
| 149 | * remove a key/value pair from the |
| 150 | * internal storage |
| 151 | * |
| 152 | * @param key name of value to remove |
| 153 | * @return value removed |
| 154 | */ |
| 155 | public Object internalRemove(Object key) |
| 156 | { |
| 157 | return context.remove( key ); |
| 158 | } |
| 159 | |
| 160 | /** |
| 161 | * Clones this context object. |
| 162 | * |
| 163 | * @return A deep copy of this <code>Context</code>. |
| 164 | */ |
| 165 | public Object clone() |
| 166 | { |
| 167 | VelocityContext clone = null; |
| 168 | try |
| 169 | { |
| 170 | clone = (VelocityContext) super.clone(); |
| 171 | clone.context = new HashMap(context); |
| 172 | } |
| 173 | catch (CloneNotSupportedException ignored) |
| 174 | { |
| 175 | } |
| 176 | return clone; |
| 177 | } |
| 178 | } |