/*
* Copyright (c) 2002-2012 Alibaba Group Holding Limited.
* All rights reserved.
*
* 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
*
* http://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 com.alibaba.citrus.turbine.support;
import static com.alibaba.citrus.util.BasicConstant.*;
import static com.alibaba.citrus.util.CollectionUtil.*;
import java.util.Set;
import com.alibaba.citrus.turbine.Context;
import com.alibaba.citrus.util.ToStringBuilder;
import com.alibaba.citrus.util.ToStringBuilder.MapBuilder;
/**
* 抽象的<code>Context</code>实现，提供了可嵌套的context机制。
*
* @author Michael Zhou
*/
public abstract class AbstractContext implements Context {
/** 父context，如果指定key在当前context不存在，则会在父context中查找。 */
private final Context parentContext;
/** 创建一个context。 */
public AbstractContext() {
this(null);
}
/** 创建一个context，指定parent context。 */
public AbstractContext(Context parentContext) {
this.parentContext = parentContext;
}
/** 取得父context，如不存在则返回<code>null</code>。 */
public Context getParentContext() {
return parentContext;
}
/** 添加一个值。 */
public final void put(String key, Object value) {
if (value == null) {
remove(key);
} else {
internalPut(key, value);
}
}
/** 取得指定值。 */
public final Object get(String key) {
Object value = internalGet(key);
if (value == null && parentContext != null) {
return parentContext.get(key);
}
return decodeValue(value);
}
/** 删除一个值。 */
public final void remove(String key) {
if (parentContext != null && parentContext.containsKey(key)) {
internalPut(key, NULL_PLACEHOLDER);
} else {
internalRemove(key);
}
}
/** 判断是否包含指定的键。 */
public final boolean containsKey(String key) {
boolean containsKey = internalContainsKey(key);
if (!containsKey && parentContext != null) {
return parentContext.containsKey(key);
}
return containsKey;
}
/** 取得所有key的集合。 */
public final Set<String> keySet() {
Set<String> internalKeySet = internalKeySet();
Set<String> parentKeySet = parentContext == null ? null : parentContext.keySet();
if (parentKeySet == null || parentKeySet.isEmpty()) {
return internalKeySet;
}
Set<String> newSet = createHashSet();
newSet.addAll(parentKeySet);
newSet.addAll(internalKeySet);
return newSet;
}
/** 取得所有key的集合。 */
protected abstract Set<String> internalKeySet();
/** 取得指定值。 */
protected abstract Object internalGet(String key);
/** 删除一个值。 */
protected abstract void internalRemove(String key);
/** 判断是否包含指定的键。 */
protected abstract boolean internalContainsKey(String key);
/** 添加一个值。 */
protected abstract void internalPut(String key, Object value);
/** 解码context的值。如果为<code>NULL_PLACEHOLDER</code>，则返回<code>null</code>。 */
private Object decodeValue(Object value) {
return value == NULL_PLACEHOLDER ? null : value;
}
@Override
public String toString() {
MapBuilder mb;
if (parentContext == null) {
mb = getMapBuilder();
} else {
mb = new MapBuilder();
mb.append("parentContext", parentContext);
mb.append("thisContext", getMapBuilder());
}
return new ToStringBuilder().append(getClass().getSimpleName()).append(mb).toString();
}
private MapBuilder getMapBuilder() {
MapBuilder mb = new MapBuilder().setSortKeys(true);
for (String key : internalKeySet()) {
mb.append(key, get(key));
}
return mb;
}
}