com.alibaba.dubbo.common.Extension Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of dubbo2 Show documentation

The all in one project of dubbo2

The newest version!

/*
 * Copyright 1999-2011 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;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

/**
 * 扩展点接口的标识。
 * 
 * 扩展点声明配置文件，格式修改。

 * 以Protocol示例，配置文件META-INF/dubbo/com.xxx.Protocol内容：

 * 由

 * 
com.foo.XxxProtocol
 com.foo.YyyProtocol


 * 改成使用KV格式

 * xxx=com.foo.XxxProtocol
 yyy=com.foo.YyyProtocol
 * 

 * 

 * 原因：

 * 当扩展点的static字段或方法签名上引用了三方库，
 * 如果三方库不存在，会导致类初始化失败，
 * Extension标识Dubbo就拿不到了，异常信息就和配置对应不起来。
 * 

 * 比如:
 * Extension("mina")加载失败，
 * 当用户配置使用mina时，就会报找不到扩展点，
 * 而不是报加载扩展点失败，以及失败原因。
 * 
 * @deprecated 因为含义广泛废弃，改用功 {@link com.alibaba.dubbo.common.extension.SPI}
 * @author william.liangf
 * @author ding.lid
 * @export
 */
@Deprecated
@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
public @interface Extension {

    /**
     * @deprecated
     */
    @Deprecated
	String value() default "";

}