/* | |
* Copyright 1999-2012 Alibaba Group. | |
* | |
* 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.dubbo.common.extension.support; | |
import java.util.Comparator; | |
import com.alibaba.dubbo.common.extension.Activate; | |
/** | |
* OrderComparetor | |
* | |
* @author william.liangf | |
*/ | |
public class ActivateComparator implements Comparator<Object> { | |
public static final Comparator<Object> COMPARATOR = new ActivateComparator(); | |
public int compare(Object o1, Object o2) { | |
if (o1 == null && o2 == null) { | |
return 0; | |
} | |
if (o1 == null) { | |
return -1; | |
} | |
if (o2 == null) { | |
return 1; | |
} | |
if (o1.equals(o2)) { | |
return 0; | |
} | |
Activate a1 = o1.getClass().getAnnotation(Activate.class); | |
Activate a2 = o2.getClass().getAnnotation(Activate.class); | |
int n1 = a1 == null ? 0 : a1.order(); | |
int n2 = a2 == null ? 0 : a2.order(); | |
return n1 > n2 ? 1 : -1; // 就算n1 == n2也不能返回0,否则在HashSet等集合中,会被认为是同一值而覆盖 | |
} | |
} |