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Posted to notifications@dubbo.apache.org by GitBox <gi...@apache.org> on 2018/07/10 06:35:30 UTC
[GitHub] diecui1202 closed pull request #33: add dubbo meetup shanghai blog
diecui1202 closed pull request #33: add dubbo meetup shanghai blog
URL: https://github.com/apache/incubator-dubbo-website/pull/33
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diff --git a/blog/en-us/dubbo-meetup-shanghai-jun-23rd-2018.md b/blog/en-us/dubbo-meetup-shanghai-jun-23rd-2018.md
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+Dubbo Shanghai meetup has been held successfully
+---
+
+The sencond Dubbo meetup has successfully been held in Shanghai, over 700 people submitted registration, and over 300 were present, more than 10,000 watched the live online. A great event again!
+
+Please enjoy the slides of the topics:
+ * Jerrick Zhu: Dubbo Status and Roadmap (Chinese) [slides](https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/dubbo-status-and-roadmap.pdf)
+ * Mercy Ma: Dubbo Cloud Native Practices and Thoughts (Chinese) [slides](https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/dubbo-cloud-native-practices-and-thoughts.pdf)
+ * Ping Guo: Nacos Open Source Initiative (Chinese) [slides](https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/nacos-open-source-initiative.pdf)
+ * Zhiwei Pan: Dubbo Practices on Internet Finance Industries (Chinese) [slides](https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/dubbo-practices-on-internet-finance-industries.pdf)
\ No newline at end of file
diff --git a/blog/zh-cn/dubbo-meetup-shanghai-jun-23rd-2018.md b/blog/zh-cn/dubbo-meetup-shanghai-jun-23rd-2018.md
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+第二届Dubbo开发者沙龙在上海成功举办
+---
+
+第二届Dubbo开发者沙龙在上海成功举办，超过700位开发者报名，现场参与人数300+，通过阿里云天池、云栖社区、大咖说引导线上直播观看次数10000+
+
+分享嘉宾及PPT:
+ * 朱勇: Dubbo开源现状与未来规划 (中文) [slides](https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/dubbo-status-and-roadmap.pdf)
+ * 小马哥: Dubbo Cloud Native 之路的实践与思考 (中文) [slides](https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/dubbo-cloud-native-practices-and-thoughts.pdf)
+ * 郭平: Nacos - 贡献Dubbo生态，阿里巴巴注册中心和配置中心开源计划 (中文) [slides](https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/nacos-open-source-initiative.pdf)
+ * 潘志伟: Dubbo在互金行业的应用场景 (中文) [slides](https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/dubbo-practices-on-internet-finance-industries.pdf)
\ No newline at end of file
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diff --git a/md_json/blog.json b/md_json/blog.json
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"filename": "dubbo-basic-usage-dubbo-provider-configuration.md",
"__html": "<h2>Dubbo基本用法-Dubbo Provider配置</h2>\n<h1>Dubbo基本用法</h1>\n<p>本章节主要讲述如何配置dubbo，按照配置方式上分，可以分为：XML配置，properties方式配置，注解方式配置，API调用方式配置。\n按照功能角度进行划分，可以分为Dubbo Provider和Dubbo Consumer。接下来章节中，分别对dubbo provider和Dubbo consumer进行讲解。</p>\n<h2>Dubbo Provider配置</h2>\n<h3>Provider 配置详解</h3>\n<p>配置Dubbo Provider有4种方式：XML配置，properties方式配置，API调用方式配置，注解方式配置。</p>\n<h4>XML配置</h4>\n<h6>最简单的配置的样例：</h6>\n<pre><code><?xml version="1.0" encoding="UTF-8"?>\n<beans xmlns="http://www.springframework.org/schema/beans"\n xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"\n xmlns:dubbo="http://dubbo.apache.org/schema/dubbo"\n xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd"> \n <dubbo:application name="hello-world-app" /> \n <dubbo:registry address="multicast://224.5.6.7:1234" /> \n <dubbo:protocol name="dubbo" port="20880" /> \n <dubbo:service interface="com.alibaba.dubbo.demo.DemoService" ref="demoServiceLocal" /> \n <dubbo:reference id="demoServiceRemote" interface="com.alibaba.dubbo.demo.DemoService" /> \n</beans>\n</code></pre>\n<p>上面样例中，注意下dubbo schema的写法：</p>\n<pre><code><beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"\n xmlns:dubbo="http://code.alibabatech.com/schema/dubbo"\n xmlns="http://www.springframework.org/schema/beans"\n xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd\n http://code.alibabatech.com/schema/dubbo http://code.alibabatech.com/schema/dubbo/dubbo.xsd">\n</code></pre>\n<h6>支持的配置标签</h6>\n<table>\n<thead>\n<tr>\n<th>标签</th>\n<th>用途</th>\n<th style=\"text-align:left\">解释</th>\n</tr>\n</thead>\n<tbody>\n<tr>\n<td><dubbo:service/></td>\n<td>服务配置</td>\n<td style=\"text-align:left\">用于暴露一个服务，定义服务的元信息，一个服务可以用多个协议暴露，一个服务也可以注册到多个注册中心</td>\n</tr>\n<tr>\n<td><dubbo:reference/></td>\n<td>引用配置</td>\n<td style=\"text-align:left\">用于创建一个远程服务代理，一个引用可以指向多个注册中心</td>\n</tr>\n<tr>\n<td><dubbo:protocol/></td>\n<td>协议配置</td>\n<td style=\"text-align:left\">用于配置提供服务的协议信息，协议由提供方指定，消费方被动接受</td>\n</tr>\n<tr>\n<td><dubbo:application/></td>\n<td>应用配置</td>\n<td style=\"text-align:left\">用于配置当前应用信息，不管该应用是提供者还是消费者</td>\n</tr>\n<tr>\n<td><dubbo:module/></td>\n<td>模块配置</td>\n<td style=\"text-align:left\">用于配置当前模块信息，可选</td>\n</tr>\n<tr>\n<td><dubbo:registry/></td>\n<td>注册中心配置</td>\n<td style=\"text-align:left\">用于配置连接注册中心相关信息</td>\n</tr>\n<tr>\n<td><dubbo:monitor/></td>\n<td>监控中心配置</td>\n<td style=\"text-align:left\">用于配置连接监控中心相关信息，可选</td>\n</tr>\n<tr>\n<td><dubbo:provider/></td>\n<td>提供方配置</td>\n<td style=\"text-align:left\">当 ProtocolConfig 和 ServiceConfig 某属性没有配置时，采用此缺省值，可选</td>\n</tr>\n<tr>\n<td><dubbo:consumer/></td>\n<td>消费方配置</td>\n<td style=\"text-align:left\">当 ReferenceConfig 某属性没有配置时，采用此缺省值，可选</td>\n</tr>\n<tr>\n<td><dubbo:method/></td>\n<td>方法配置</td>\n<td style=\"text-align:left\">用于 ServiceConfig 和 ReferenceConfig 指定方法级的配置信息</td>\n</tr>\n<tr>\n<td><dubbo:argument/></td>\n<td>参数配置</td>\n<td style=\"text-align:left\">用于指定方法参数配置</td>\n</tr>\n</tbody>\n</table>\n<p><img src=\"https://cdn.yuque.com/lark/0/2018/png/15841/1527849348155-8423d401-9ea4-4dc6-8720-d9e3d90963b6.png\" alt=\"undefined\"></p>\n <center>配置之间关系图</center>\n<h6>配置项详解</h6>\n<ul>\n<li>\n<p><dubbo:application name="hello-world-app" /><br>\n用于指定应用名，这里需要保证应用名唯一，这个应用名在后续的console admin中可以在列表中显示，方便管理。</p>\n</li>\n<li>\n<p><dubbo:registry address="multicast://224.5.6.7:1234" /><br>\n注册中心配置，和服务发现的具体机制有关系。可以是zookeeper地质，也可以eureka地质。上面这个是广播地址，在本地服务调用的测试过程中非常方便。</p>\n</li>\n<li>\n<p><dubbo:protocol name="dubbo" port="20880" /><br>\n这里是传输的协议和默认端口，一般不需要更改。</p>\n</li>\n</ul>\n<blockquote>\n<p>接下来重点讲解下<dubbo:service/>的配置。</p>\n</blockquote>\n<ul>\n<li><dubbo:service/>支持的主要属性列表：\n| 属性名 | 说明 |\n| -------- | ----- |\n| version | 版本号 |\n| scope | 服务可见性, 值为：local 或者 remote，默认为remote |\n| actives | 最大的激活的请求数 |\n| async | 方法调用是否异步，默认为false |\n| cache | 服务缓存，可选值：lru/threadlocal/jcache |\n| callbacks | callback实例的限制 |\n| generic | 泛化调用，可以绕过 |\n| class | Service的实现的类名 |\n| connections | 这个服务里的连接数 |\n| delay | 发布服务延迟的毫秒数 |\n| executes | 服务执行的请求上限 |\n| retries | 超时重试次数 |\n| timeout | 调用超时时间 |</li>\n</ul>\n<p>其他配置属性请参考xsd：<a href=\"http://dubbo.apache.org/schema/dubbo/dubbo.xsd\">http://dubbo.apache.org/schema/dubbo/dubbo.xsd</a></p>\n<ul>\n<li><dubbo:method/>作为<dubbo:service/>的子元素，它可以针对方法进行配置。比较常用的属性有：</li>\n</ul>\n<table>\n<thead>\n<tr>\n<th>属性名</th>\n<th>说明</th>\n</tr>\n</thead>\n<tbody>\n<tr>\n<td>executes</td>\n<td>服务执行的请求上限</td>\n</tr>\n<tr>\n<td>retries</td>\n<td>超时重试次数</td>\n</tr>\n<tr>\n<td>timeout</td>\n<td>调用超时时间</td>\n</tr>\n</tbody>\n</table>\n<p>其他属性，可以参考上面的xsd。</p>\n<h6>配置的覆盖关系</h6>\n<p><img src=\"https://cdn.yuque.com/lark/0/2018/png/15841/1527849374313-94a5ea24-0e72-4d83-871b-e0e95eab646a.png\" alt=\"undefined\"></p>\n<center>配置的覆盖关系图</center>\n<p>这里的覆盖关系包含了Provider和Consumer两端的配置，如果对consumer有疑问，可以参考后一章节的consumer章节之后再来理解。</p>\n<h4>dubbo.properties方式配置</h4>\n<blockquote>\n<p>如果公共配置很简单，没有多注册中心，多协议等情况，或者想多个 Spring 容器想共享配置，可以使用 dubbo.properties 作为缺省配置。</p>\n</blockquote>\n<p>Dubbo 将自动加载 classpath 根目录下的 dubbo.properties，可以通过JVM启动参数 -Ddubbo.properties.file=xxx.properties 改变缺省配置位置。</p>\n<h6>dubbo.properties配置样例</h6>\n<pre><code># 应用名\ndubbo.application.name=dubbodemo-provider\n# 注册中心地址\ndubbo.registry.address=zookeeper://localhost:2181\n# 广播的注册中心样例\n#dubbo.registry.address=multicast://224.5.6.7:1234\n# 调用协议地址\ndubbo.protocol.name=dubbo\ndubbo.protocol.port=28080\n</code></pre>\n<h6>映射规则</h6>\n<p>将 XML 配置的标签名，加属性名，用点分隔，多个属性拆成多行</p>\n<ul>\n<li>比如：dubbo.application.name=foo等价于<dubbo:application name="foo" /></li>\n<li>比如：dubbo.registry.address=10.20.153.10:9090等价于<dubbo:registry address="10.20.153.10:9090" /></li>\n</ul>\n<p>如果 XML 有多行同名标签配置，可用 id 号区分，如果没有 id 号将对所有同名标签生效</p>\n<ul>\n<li>比如：dubbo.protocol.rmi.port=1234等价于<dubbo:protocol id="rmi" name="rmi" port="1099" /> 2</li>\n<li>比如：dubbo.registry.china.address=10.20.153.10:9090等价于<dubbo:registry id="china" address="10.20.153.10:9090" /></li>\n</ul>\n<h6>覆盖策略</h6>\n<p><img src=\"https://cdn.yuque.com/lark/0/2018/png/15841/1527849393591-2c3de248-1b3d-47d3-bd10-8b415e9fcd39.png\" alt=\"undefined\"></p>\n<ul>\n<li>JVM 启动 -D 参数优先，这样可以使用户在部署和启动时进行参数重写，比如在启动时需改变协议的端口。</li>\n<li>XML 次之，如果在 XML 中有配置，则 dubbo.properties 中的相应配置项无效。</li>\n<li>Properties 最后，相当于缺省值，只有 XML 没有配置时，dubbo.properties 的相应配置项才会生效，通常用于共享公共配置，比如应用名。</li>\n</ul>\n<blockquote>\n<p>注意：</p>\n</blockquote>\n<ol>\n<li>如果 classpath 根目录下存在多个 dubbo.properties，比如多个 jar 包中有 dubbo.properties，Dubbo 会任意加载，并打印 Error 日志，后续可能改为抛异常。 ↩</li>\n<li>协议的 id 没配时，缺省使用协议名作为 id</li>\n</ol>\n<h4>annotation</h4>\n<h6>Service注解暴露服务</h6>\n<pre><code>import com.alibaba.dubbo.config.annotation.Service;\n\n@Service(timeout = 5000)\npublic class AnnotateServiceImpl implements AnnotateService { \n // ...\n}\n</code></pre>\n<h6>javaconfig形式配置公共模块</h6>\n<pre><code>@Configuration\npublic class DubboConfiguration {\n\n @Bean\n public ApplicationConfig applicationConfig() {\n ApplicationConfig applicationConfig = new ApplicationConfig();\n applicationConfig.setName("provider-test");\n return applicationConfig;\n }\n\n @Bean\n public RegistryConfig registryConfig() {\n RegistryConfig registryConfig = new RegistryConfig();\n registryConfig.setAddress("zookeeper://127.0.0.1:2181");\n registryConfig.setClient("curator");\n return registryConfig;\n }\n}\n</code></pre>\n<p>这种方式的配置和前面用xml配置的方式是一样的效果。</p>\n<h6>指定dubbo扫描路径</h6>\n<pre><code>@SpringBootApplication\n@DubboComponentScan(basePackages = "com.alibaba.dubbo.test.service.impl")\npublic class ProviderTestApp {\n // ...\n}\n</code></pre>\n<p>或者使用spring bean xml配置方式：</p>\n<pre><code><dubbo:annotation package="com.chanshuyi.service.impl" />\n</code></pre>\n<h4>api直接触发</h4>\n<pre><code>import com.alibaba.dubbo.rpc.config.ApplicationConfig;\nimport com.alibaba.dubbo.rpc.config.RegistryConfig;\nimport com.alibaba.dubbo.rpc.config.ProviderConfig;\nimport com.alibaba.dubbo.rpc.config.ServiceConfig;\nimport com.xxx.XxxService;\nimport com.xxx.XxxServiceImpl;\n\n// 服务实现\nXxxService xxxService = new XxxServiceImpl();\n\n// 当前应用配置\nApplicationConfig application = new ApplicationConfig();\napplication.setName("xxx");\n\n// 连接注册中心配置\nRegistryConfig registry = new RegistryConfig();\nregistry.setAddress("10.20.130.230:9090");\nregistry.setUsername("aaa");\nregistry.setPassword("bbb");\n\n// 服务提供者协议配置\nProtocolConfig protocol = new ProtocolConfig();\nprotocol.setName("dubbo");\nprotocol.setPort(12345);\nprotocol.setThreads(200);\n\n// 注意：ServiceConfig为重对象，内部封装了与注册中心的连接，以及开启服务端口\n\n// 服务提供者暴露服务配置\nServiceConfig<XxxService> service = new ServiceConfig<XxxService>(); // 此实例很重，封装了与注册中心的连接，请自行缓存，否则可能造成内存和连接泄漏\nservice.setApplication(application);\nservice.setRegistry(registry); // 多个注册中心可以用setRegistries()\nservice.setProtocol(protocol); // 多个协议可以用setProtocols()\nservice.setInterface(XxxService.class);\nservice.setRef(xxxService);\nservice.setVersion("1.0.0");\n\n// 暴露及注册服务\nservice.export();\n</code></pre>\n<p>一般在spring应用中，不推荐使用这种方式。 具体的含义这里不做解释，可以通过github查看源码。</p>\n<h3>Provider 接口和实现</h3>\n<p>上面章节更多从配置角度出发，接下来通过一个完整的例子，来讲解下dubbo provider的完整使用。</p>\n<p>这个例子中只有一个服务UserReadService，有一个方法 getUserById。 需要将这个服务通过Dubbo暴露给远程的服务。具体的步骤如下：</p>\n<p>1.创建工程\n如果本来已经有工程，可以忽略。创建一个spring boot工程，可以通过 <a href=\"https://start.spring.io/\">https://start.spring.io/</a> 创建。\n2.定义接口\n定义接口：UserReadService</p>\n<pre><code>public interface UserReadService{\npublic User getUserById(Long userId);\n}\n</code></pre>\n<p>这个接口一般来说会放到独立的jar包里，作为client包。 其他应用要消费这个服务的时候，一般来说需要应用引用这个client包。(除了泛化调用)\n3.实现接口\n实现UserReadService, 当前实现部署在Provider的应用中。</p>\n<pre><code>public UserReadServiceImpl implements UserReadService{\n public User getUserById(Long userId){\n return xxx;\n }\n}\n</code></pre>\n<p>4.Dubbo配置</p>\n<pre><code><?xml version="1.0" encoding="UTF-8"?>\n<beans xmlns="http://www.springframework.org/schema/beans"\n xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"\n xmlns:dubbo="http://dubbo.apache.org/schema/dubbo"\n xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-4.3.xsd http://dubbo.apache.org/schema/dubbo http://dubbo.apache.org/schema/dubbo/dubbo.xsd"> \n <dubbo:application name="hello-world-app" /> \n <dubbo:registry address="multicast://224.5.6.7:1234" /> \n <dubbo:protocol name="dubbo" port="20880" /> \n <bean id="userReadService" class="com.package.UserReadServiceImpl"/>\n <dubbo:service interface="com.package.UserReadService" ref="userReadService" /> \n</beans>\n</code></pre>\n<p>Dubbo配置的其他方式可以参考上一章节的相关配置，或者使用集成dubbo spring boot starter方式。</p>\n"
},
+ {
+ "filename": "dubbo-meetup-shanghai-jun-23rd-2018.md",
+ "__html": "<h2>第二届Dubbo开发者沙龙在上海成功举办</h2>\n<p>第二届Dubbo开发者沙龙在上海成功举办，超过700位开发者报名，现场参与人数300+，通过阿里云天池、云栖社区、大咖说引导线上直播观看次数10000+</p>\n<p>分享嘉宾及PPT:</p>\n<ul>\n<li>朱勇: Dubbo开源现状与未来规划 (中文) <a href=\"https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/dubbo-status-and-roadmap.pdf\">slides</a></li>\n<li>小马哥: Dubbo Cloud Native 之路的实践与思考 (中文) <a href=\"https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/dubbo-cloud-native-practices-and-thoughts.pdf\">slides</a></li>\n<li>郭平: Nacos - 贡献Dubbo生态，阿里巴巴注册中心和配置中心开源计划 (中文) <a href=\"https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/nacos-open-source-initiative.pdf\">slides</a></li>\n<li>潘志伟: Dubbo在互金行业的应用场景 (中文) <a href=\"https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/dubbo-practices-on-internet-finance-industries.pdf\">slides</a></li>\n</ul>\n"
+ },
{
"filename": "introduction-to-dubbo-spi-2.md",
"__html": "<h1>Dubbo可扩展机制源码解析</h1>\n<hr>\n<p>在<a href=\"#/blog/introduction-to-dubbo-spi.md\">Dubbo可扩展机制实战</a>中，我们了解了Dubbo扩展机制的一些概念，初探了Dubbo中LoadBalance的实现，并自己实现了一个LoadBalance。是不是觉得Dubbo的扩展机制很不错呀，接下来，我们就深入Dubbo的源码，一睹庐山真面目。</p>\n<h1>ExtensionLoader</h1>\n<p>ExtentionLoader是最核心的类，负责扩展点的加载和生命周期管理。我们就以这个类开始吧。\nExtension的方法比较多，比较常用的方法有:</p>\n<ul>\n<li><code>public static <T> ExtensionLoader<T> getExtensionLoader(Class<T> type)</code></li>\n<li><code>public T getExtension(String name)</code></li>\n<li><code>public T getAdaptiveExtension()</code></li>\n</ul>\n<p>比较常见的用法有:</p>\n<ul>\n<li><code>LoadBalance lb = ExtensionLoader.getExtensionLoader(LoadBalance.class).getExtension(loadbalanceName)</code></li>\n<li><code>RouterFactory routerFactory = ExtensionLoader.getExtensionLoader(RouterFactory.class).getAdaptiveExtension()</code></li>\n</ul>\n<p>说明：在接下来展示的源码中，我会将无关的代码(比如日志，异常捕获等)去掉，方便大家阅读和理解。</p>\n<ol>\n<li>getExtensionLoader方法\n这是一个静态工厂方法，入参是一个可扩展的接口，返回一个该接口的ExtensionLoader实体类。通过这个实体类，可以根据name获得具体的扩展，也可以获得一个自适应扩展。</li>\n</ol>\n<pre><code class=\"language-java\"><span class=\"hljs-keyword\">public</span> <span class=\"hljs-keyword\">static</span> <T> <span class=\"hljs-function\">ExtensionLoader<T> <span class=\"hljs-title\">getExtensionLoader</span><span class=\"hljs-params\">(Class<T> type)</span> </span>{\n <span class=\"hljs-comment\">// 扩展点必须是接口</span>\n <span class=\"hljs-keyword\">if</span> (!type.isInterface()) {\n <span class=\"hljs-keyword\">throw</span> <span class=\"hljs-keyword\">new</span> IllegalArgumentException(<span class=\"hljs-string\">\"Extension type(\"</span> + type + <span class=\"hljs-string\">\") is not interface!\"</span>);\n }\n <span class=\"hljs-comment\">// 必须要有@SPI注解</span>\n <span class=\"hljs-keyword\">if</span> (!withExtensionAnnotation(type)) {\n <span class=\"hljs-keyword\">throw</span> <span class=\"hljs-keyword\">new</span> IllegalArgumentException(<span class=\"hljs-string\">\"Extension type without @SPI Annotation!\"</span>);\n }\n <span class=\"hljs-comment\">// 从缓存中根据接口获取对应的ExtensionLoader</span>\n <span class=\"hljs-comment\">// 每个扩展只会被加载一次</span>\n ExtensionLoader<T> loader = (ExtensionLoader<T>) EXTENSION_LOADERS.get(type);\n <span class=\"hljs-keyword\">if</span> (loader == <span class=\"hljs-keyword\">null</span>) {\n <span class=\"hljs-comment\">// 初始化扩展</span>\n EXTENSION_LOADERS.putIfAbsent(type, <span class=\"hljs-keyword\">new</span> ExtensionLoader<T>(type));\n loader = (ExtensionLoader<T>) EXTENSION_LOADERS.get(type);\n }\n <span class=\"hljs-keyword\">return</span> loader;\n }\n \n<span class=\"hljs-function\"><span class=\"hljs-keyword\">private</span> <span class=\"hljs-title\">ExtensionLoader</span><span class=\"hljs-params\">(Class<?> type)</span> </span>{\n <span class=\"hljs-keyword\">this</span>.type = type;\n objectFactory = (type == ExtensionFactory.class ? <span class=\"hljs-keyword\">null</span> : ExtensionLoader.getExtensionLoader(ExtensionFactory.class).getAdaptiveExtension());\n }\n</code></pre>\n<ol start=\"2\">\n<li>getExtension方法</li>\n</ol>\n<pre><code class=\"language-java\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">public</span> T <span class=\"hljs-title\">getExtension</span><span class=\"hljs-params\">(String name)</span> </span>{\n Holder<Object> holder = cachedInstances.get(name);\n <span class=\"hljs-keyword\">if</span> (holder == <span class=\"hljs-keyword\">null</span>) {\n cachedInstances.putIfAbsent(name, <span class=\"hljs-keyword\">new</span> Holder<Object>());\n holder = cachedInstances.get(name);\n }\n Object instance = holder.get();\n <span class=\"hljs-comment\">// 从缓存中获取，如果不存在就创建</span>\n <span class=\"hljs-keyword\">if</span> (instance == <span class=\"hljs-keyword\">null</span>) {\n <span class=\"hljs-keyword\">synchronized</span> (holder) {\n instance = holder.get();\n <span class=\"hljs-keyword\">if</span> (instance == <span class=\"hljs-keyword\">null</span>) {\n instance = createExtension(name);\n holder.set(instance);\n }\n }\n }\n <span class=\"hljs-keyword\">return</span> (T) instance;\n }\n</code></pre>\n<p>getExtention方法中做了一些判断和缓存，主要的逻辑在createExtension方法中。我们继续看createExtention方法。</p>\n<pre><code class=\"language-java\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">private</span> T <span class=\"hljs-title\">createExtension</span><span class=\"hljs-params\">(String name)</span> </span>{\n <span class=\"hljs-comment\">// 根据扩展点名称得到扩展类，比如对于LoadBalance，根据random得到RandomLoadBalance类</span>\n Class<?> clazz = getExtensionClasses().get(name);\n \n T instance = (T) EXTENSION_INSTANCES.get(clazz);\n <span class=\"hljs-keyword\">if</span> (instance == <span class=\"hljs-keyword\">null</span>) {\n <span class=\"hljs-comment\">// 使用反射调用nesInstance来创建扩展类的一个示例</span>\n EXTENSION_INSTANCES.putIfAbsent(clazz, (T) clazz.newInstance());\n instance = (T) EXTENSION_INSTANCES.get(clazz);\n }\n <span class=\"hljs-comment\">// 对扩展类示例进行依赖注入</span>\n injectExtension(instance);\n <span class=\"hljs-comment\">// 如果有wrapper，添加wrapper</span>\n Set<Class<?>> wrapperClasses = cachedWrapperClasses;\n <span class=\"hljs-keyword\">if</span> (wrapperClasses != <span class=\"hljs-keyword\">null</span> && !wrapperClasses.isEmpty()) {\n <span class=\"hljs-keyword\">for</span> (Class<?> wrapperClass : wrapperClasses) {\n instance = injectExtension((T) wrapperClass.getConstructor(type).newInstance(instance));\n }\n }\n <span class=\"hljs-keyword\">return</span> instance;\n}\n</code></pre>\n<p>createExtension方法做了以下事情:</p>\n<ol>\n<li>先根据name来得到对应的扩展类。从ClassPath下<code>META-INF</code>文件夹下读取扩展点配置文件。</li>\n<li>使用反射创建一个扩展类的实例</li>\n<li>对扩展类实例的属性进行依赖注入，即IoC。</li>\n<li>如果有wrapper，添加wrapper。即AoP。</li>\n</ol>\n<p>下面我们来重点看下这4个过程</p>\n<ol>\n<li>根据name获取对应的扩展类\n先看代码:</li>\n</ol>\n<pre><code class=\"language-java\"><span class=\"hljs-keyword\">private</span> Map<String, Class<?>> getExtensionClasses() {\n Map<String, Class<?>> classes = cachedClasses.get();\n <span class=\"hljs-keyword\">if</span> (classes == <span class=\"hljs-keyword\">null</span>) {\n <span class=\"hljs-keyword\">synchronized</span> (cachedClasses) {\n classes = cachedClasses.get();\n <span class=\"hljs-keyword\">if</span> (classes == <span class=\"hljs-keyword\">null</span>) {\n classes = loadExtensionClasses();\n cachedClasses.set(classes);\n }\n }\n }\n <span class=\"hljs-keyword\">return</span> classes;\n }\n\n <span class=\"hljs-comment\">// synchronized in getExtensionClasses</span>\n <span class=\"hljs-keyword\">private</span> Map<String, Class<?>> loadExtensionClasses() {\n <span class=\"hljs-keyword\">final</span> SPI defaultAnnotation = type.getAnnotation(SPI.class);\n <span class=\"hljs-keyword\">if</span> (defaultAnnotation != <span class=\"hljs-keyword\">null</span>) {\n String value = defaultAnnotation.value();\n <span class=\"hljs-keyword\">if</span> (value != <span class=\"hljs-keyword\">null</span> && (value = value.trim()).length() > <span class=\"hljs-number\">0</span>) {\n String[] names = NAME_SEPARATOR.split(value);\n <span class=\"hljs-keyword\">if</span> (names.length > <span class=\"hljs-number\">1</span>) {\n <span class=\"hljs-keyword\">throw</span> <span class=\"hljs-keyword\">new</span> IllegalStateException(<span class=\"hljs-string\">\"more than 1 default extension name on extension \"</span> + type.getName());\n }\n <span class=\"hljs-keyword\">if</span> (names.length == <span class=\"hljs-number\">1</span>) cachedDefaultName = names[<span class=\"hljs-number\">0</span>];\n }\n }\n\n Map<String, Class<?>> extensionClasses = <span class=\"hljs-keyword\">new</span> HashMap<String, Class<?>>();\n loadFile(extensionClasses, DUBBO_INTERNAL_DIRECTORY);\n loadFile(extensionClasses, DUBBO_DIRECTORY);\n loadFile(extensionClasses, SERVICES_DIRECTORY);\n <span class=\"hljs-keyword\">return</span> extensionClasses;\n }\n</code></pre>\n<p>过程很简单，先从缓存中获取，如果没有，就从配置文件中加载。配置文件的路径就是之前提到的:</p>\n<ul>\n<li><code>META-INF/dubbo/internal</code></li>\n<li><code>META-INF/dubbo</code></li>\n<li><code>META-INF/services</code></li>\n</ul>\n<ol start=\"2\">\n<li>使用反射创建扩展实例\n这个过程很简单，使用<code>clazz.newInstance())</code>来完成。创建的扩展实例的属性都是空值。</li>\n<li>扩展实例自动装配\n在实际的场景中，类之间都是有依赖的。扩展实例中也会引用一些依赖，比如简单的Java类，另一个Dubbo的扩展或一个Spring Bean等。依赖的情况很复杂，Dubbo的处理也相对复杂些。我们稍后会有专门的章节对其进行说明，现在，我们只需要知道，Dubbo可以正确的注入扩展点中的普通依赖，Dubbo扩展依赖或Spring依赖等。</li>\n<li>扩展实例自动包装\n自动包装就是要实现类似于Spring的AOP功能。Dubbo利用它在内部实现一些通用的功能，比如日志，监控等。关于扩展实例自动包装的内容，也会在后面单独讲解。</li>\n</ol>\n<p>经过上面的4步，Dubbo就创建并初始化了一个扩展实例。这个实例的依赖被注入了，也根据需要被包装了。到此为止，这个扩展实例就可以被使用了。</p>\n<h1>Dubbo SPI高级用法之自动装配</h1>\n<p>自动装配的相关代码在injectExtension方法中:</p>\n<pre><code class=\"language-java\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">private</span> T <span class=\"hljs-title\">injectExtension</span><span class=\"hljs-params\">(T instance)</span> </span>{\n <span class=\"hljs-keyword\">for</span> (Method method : instance.getClass().getMethods()) {\n <span class=\"hljs-keyword\">if</span> (method.getName().startsWith(<span class=\"hljs-string\">\"set\"</span>)\n && method.getParameterTypes().length == <span class=\"hljs-number\">1</span>\n && Modifier.isPublic(method.getModifiers())) {\n Class<?> pt = method.getParameterTypes()[<span class=\"hljs-number\">0</span>];\n \n String property = method.getName().length() > <span class=\"hljs-number\">3</span> ? method.getName().substring(<span class=\"hljs-number\">3</span>, <span class=\"hljs-number\">4</span>).toLowerCase() + method.getName().substring(<span class=\"hljs-number\">4</span>) : <span class=\"hljs-string\">\"\"</span>;\n Object object = objectFactory.getExtension(pt, property);\n <span class=\"hljs-keyword\">if</span> (object != <span class=\"hljs-keyword\">null</span>) {\n method.invoke(instance, object);\n }\n }\n }\n <span class=\"hljs-keyword\">return</span> instance;\n}\n</code></pre>\n<p>要实现对扩展实例的依赖的自动装配，首先需要知道有哪些依赖，这些依赖的类型是什么。Dubbo的方案是查找Java标准的setter方法。即方法名以set开始，只有一个参数。如果扩展类中有这样的set方法，Dubbo会对其进行依赖注入，类似于Spring的set方法注入。\n但是Dubbo中的依赖注入比Spring要复杂，因为Spring注入的都是Spring bean，都是由Spring容器来管理的。而Dubbo的依赖注入中，需要注入的可能是另一个Dubbo的扩展，也可能是一个Spring Bean，或是Google guice的组件，或其他任何一个框架中的组件。Dubbo需要能够从任何一个场景中加载扩展。在injectExtension方法中，是用<code>Object object = objectFactory.getExtension(pt, property)</code>来实现的。objectFactory是ExtensionFactory类型的，在创建ExtensionLoader时被初始化:</p>\n<pre><code class=\"language-java\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">private</span> <span class=\"hljs-title\">ExtensionLoader</span><span class=\"hljs-params\">(Class<?> type)</span> </span>{\n <span class=\"hljs-keyword\">this</span>.type = type;\n objectFactory = (type == ExtensionFactory.class ? <span class=\"hljs-keyword\">null</span> : ExtensionLoader.getExtensionLoader(ExtensionFactory.class).getAdaptiveExtension());\n }\n</code></pre>\n<p>objectFacory本身也是一个扩展，通过<code>ExtensionLoader.getExtensionLoader(ExtensionFactory.class).getAdaptiveExtension())</code>来获取。</p>\n<p><img src=\"https://raw.githubusercontent.com/vangoleo/wiki/master/dubbo/dubbo-extensionfactory.png\" alt=\"Dubbo-ExtensionFactory | left\"></p>\n<p>ExtensionLoader有三个实现：</p>\n<ol>\n<li>SpiExtensionLoader：Dubbo自己的Spi去加载Extension</li>\n<li>SpringExtensionLoader：从Spring容器中去加载Extension</li>\n<li>AdaptiveExtensionLoader: 自适应的AdaptiveExtensionLoader</li>\n</ol>\n<p>这里要注意AdaptiveExtensionLoader，源码如下:</p>\n<pre><code class=\"language-java\"><span class=\"hljs-meta\">@Adaptive</span>\n<span class=\"hljs-keyword\">public</span> <span class=\"hljs-class\"><span class=\"hljs-keyword\">class</span> <span class=\"hljs-title\">AdaptiveExtensionFactory</span> <span class=\"hljs-keyword\">implements</span> <span class=\"hljs-title\">ExtensionFactory</span> </span>{\n\n <span class=\"hljs-keyword\">private</span> <span class=\"hljs-keyword\">final</span> List<ExtensionFactory> factories;\n\n <span class=\"hljs-function\"><span class=\"hljs-keyword\">public</span> <span class=\"hljs-title\">AdaptiveExtensionFactory</span><span class=\"hljs-params\">()</span> </span>{\n ExtensionLoader<ExtensionFactory> loader = ExtensionLoader.getExtensionLoader(ExtensionFactory.class);\n List<ExtensionFactory> list = <span class=\"hljs-keyword\">new</span> ArrayList<ExtensionFactory>();\n <span class=\"hljs-keyword\">for</span> (String name : loader.getSupportedExtensions()) {\n list.add(loader.getExtension(name));\n }\n factories = Collections.unmodifiableList(list);\n }\n\n <span class=\"hljs-keyword\">public</span> <T> <span class=\"hljs-function\">T <span class=\"hljs-title\">getExtension</span><span class=\"hljs-params\">(Class<T> type, String name)</span> </span>{\n <span class=\"hljs-keyword\">for</span> (ExtensionFactory factory : factories) {\n T extension = factory.getExtension(type, name);\n <span class=\"hljs-keyword\">if</span> (extension != <span class=\"hljs-keyword\">null</span>) {\n <span class=\"hljs-keyword\">return</span> extension;\n }\n }\n <span class=\"hljs-keyword\">return</span> <span class=\"hljs-keyword\">null</span>;\n }\n}\n</code></pre>\n<p>AdaptiveExtensionLoader类有@Adaptive注解。前面提到了，Dubbo会为每一个扩展创建一个自适应实例。如果扩展类上有@Adaptive，会使用该类作为自适应类。如果没有，Dubbo会为我们创建一个。所以<code>ExtensionLoader.getExtensionLoader(ExtensionFactory.class).getAdaptiveExtension())</code>会返回一个AdaptiveExtensionLoader实例，作为自适应扩展实例。\nAdaptiveExtentionLoader会遍历所有的ExtensionFactory实现，尝试着去加载扩展。如果找到了，返回。如果没有，在下一个ExtensionFactory中继续找。Dubbo内置了两个ExtensionFactory，分别从Dubbo自身的扩展机制和Spring容器中去寻找。由于ExtensionFactory本身也是一个扩展点，我们可以实现自己的ExtensionFactory，让Dubbo的自动装配支持我们自定义的组件。比如，我们在项目中使用了Google的guice这个IoC容器。我们可以实现自己的GuiceExtensionFactory，让Dubbo支持从guice容器中加载扩展。</p>\n<h1>Dubbo SPI高级用法之AoP</h1>\n<p>在用Spring的时候，我们经常会用到AOP功能。在目标类的方法前后插入其他逻辑。比如通常使用Spring AOP来实现日志，监控和鉴权等功能。\nDubbo的扩展机制，是否也支持类似的功能呢？答案是yes。在Dubbo中，有一种特殊的类，被称为Wrapper类。通过装饰者模式，使用包装类包装原始的扩展点实例。在原始扩展点实现前后插入其他逻辑，实现AOP功能。</p>\n<h3>什么是Wrapper类</h3>\n<p>那什么样类的才是Dubbo扩展机制中的Wrapper类呢？Wrapper类是一个有复制构造函数的类，也是典型的装饰者模式。下面就是一个Wrapper类:</p>\n<pre><code class=\"language-java\"><span class=\"hljs-class\"><span class=\"hljs-keyword\">class</span> <span class=\"hljs-title\">A</span></span>{\n <span class=\"hljs-keyword\">private</span> A a;\n <span class=\"hljs-function\"><span class=\"hljs-keyword\">public</span> <span class=\"hljs-title\">A</span><span class=\"hljs-params\">(A a)</span></span>{\n <span class=\"hljs-keyword\">this</span>.a = a;\n }\n}\n</code></pre>\n<p>类A有一个构造函数<code>public A(A a)</code>，构造函数的参数是A本身。这样的类就可以成为Dubbo扩展机制中的一个Wrapper类。Dubbo中这样的Wrapper类有ProtocolFilterWrapper, ProtocolListenerWrapper等, 大家可以查看源码加深理解。</p>\n<h3>怎么配置Wrapper类</h3>\n<p>在Dubbo中Wrapper类也是一个扩展点，和其他的扩展点一样，也是在<code>META-INF</code>文件夹中配置的。比如前面举例的ProtocolFilterWrapper和ProtocolListenerWrapper就是在路径<code>dubbo-rpc/dubbo-rpc-api/src/main/resources/META-INF/dubbo/internal/com.alibaba.dubbo.rpc.Protocol</code>中配置的:</p>\n<pre><code class=\"language-text\">filter=com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper\nlistener=com.alibaba.dubbo.rpc.protocol.ProtocolListenerWrapper\nmock=com.alibaba.dubbo.rpc.support.MockProtocol\n</code></pre>\n<p>在Dubbo加载扩展配置文件时，有一段如下的代码:</p>\n<pre><code class=\"language-java\"><span class=\"hljs-keyword\">try</span> { \n clazz.getConstructor(type); \n Set<Class<?>> wrappers = cachedWrapperClasses;\n <span class=\"hljs-keyword\">if</span> (wrappers == <span class=\"hljs-keyword\">null</span>) {\n cachedWrapperClasses = <span class=\"hljs-keyword\">new</span> ConcurrentHashSet<Class<?>>();\n wrappers = cachedWrapperClasses;\n }\n wrappers.add(clazz);\n} <span class=\"hljs-keyword\">catch</span> (NoSuchMethodException e) {}\n</code></pre>\n<p>这段代码的意思是，如果扩展类有复制构造函数，就把该类存起来，供以后使用。有复制构造函数的类就是Wrapper类。通过<code>clazz.getConstructor(type)</code>来获取参数是扩展点接口的构造函数。注意构造函数的参数类型是扩展点接口，而不是扩展类。\n以Protocol为例。配置文件<code>dubbo-rpc/dubbo-rpc-api/src/main/resources/META-INF/dubbo/internal/com.alibaba.dubbo.rpc.Protocol</code>中定义了<code>filter=com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper</code>。\nProtocolFilterWrapper代码如下：</p>\n<pre><code class=\"language-java\"><span class=\"hljs-keyword\">public</span> <span class=\"hljs-class\"><span class=\"hljs-keyword\">class</span> <span class=\"hljs-title\">ProtocolFilterWrapper</span> <span class=\"hljs-keyword\">implements</span> <span class=\"hljs-title\">Protocol</span> </span>{\n\n <span class=\"hljs-keyword\">private</span> <span class=\"hljs-keyword\">final</span> Protocol protocol;\n\n <span class=\"hljs-comment\">// 有一个参数是Protocol的复制构造函数</span>\n <span class=\"hljs-function\"><span class=\"hljs-keyword\">public</span> <span class=\"hljs-title\">ProtocolFilterWrapper</span><span class=\"hljs-params\">(Protocol protocol)</span> </span>{\n <span class=\"hljs-keyword\">if</span> (protocol == <span class=\"hljs-keyword\">null</span>) {\n <span class=\"hljs-keyword\">throw</span> <span class=\"hljs-keyword\">new</span> IllegalArgumentException(<span class=\"hljs-string\">\"protocol == null\"</span>);\n }\n <span class=\"hljs-keyword\">this</span>.protocol = protocol;\n }\n</code></pre>\n<p>ProtocolFilterWrapper有一个构造函数<code>public ProtocolFilterWrapper(Protocol protocol)</code>，参数是扩展点Protocol，所以它是一个Dubbo扩展机制中的Wrapper类。ExtensionLoader会把它缓存起来，供以后创建Extension实例的时候，使用这些包装类依次包装原始扩展点。</p>\n<h1>扩展点自适应</h1>\n<p>前面讲到过，Dubbo需要在运行时根据方法参数来决定该使用哪个扩展，所以有了扩展点自适应实例。其实是一个扩展点的代理，将扩展的选择从Dubbo启动时，延迟到RPC调用时。Dubbo中每一个扩展点都有一个自适应类，如果没有显式提供，Dubbo会自动为我们创建一个，默认使用Javaassist。\n先来看下创建自适应扩展类的代码:</p>\n<pre><code class=\"language-java\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">public</span> T <span class=\"hljs-title\">getAdaptiveExtension</span><span class=\"hljs-params\">()</span> </span>{\n Object instance = cachedAdaptiveInstance.get();\n <span class=\"hljs-keyword\">if</span> (instance == <span class=\"hljs-keyword\">null</span>) {\n <span class=\"hljs-keyword\">synchronized</span> (cachedAdaptiveInstance) {\n instance = cachedAdaptiveInstance.get();\n <span class=\"hljs-keyword\">if</span> (instance == <span class=\"hljs-keyword\">null</span>) {\n instance = createAdaptiveExtension();\n cachedAdaptiveInstance.set(instance); \n }\n } \n }\n\n <span class=\"hljs-keyword\">return</span> (T) instance;\n}\n</code></pre>\n<p>继续看createAdaptiveExtension方法</p>\n<pre><code class=\"language-java\"><span class=\"hljs-function\"><span class=\"hljs-keyword\">private</span> T <span class=\"hljs-title\">createAdaptiveExtension</span><span class=\"hljs-params\">()</span> </span>{ \n <span class=\"hljs-keyword\">return</span> injectExtension((T) getAdaptiveExtensionClass().newInstance());\n}\n</code></pre>\n<p>继续看getAdaptiveExtensionClass方法</p>\n<pre><code class=\"language-java\"><span class=\"hljs-keyword\">private</span> Class<?> getAdaptiveExtensionClass() {\n getExtensionClasses();\n <span class=\"hljs-keyword\">if</span> (cachedAdaptiveClass != <span class=\"hljs-keyword\">null</span>) {\n <span class=\"hljs-keyword\">return</span> cachedAdaptiveClass;\n }\n <span class=\"hljs-keyword\">return</span> cachedAdaptiveClass = createAdaptiveExtensionClass();\n }\n</code></pre>\n<p>继续看createAdaptiveExtensionClass方法，绕了一大圈，终于来到了具体的实现了。看这个createAdaptiveExtensionClass方法，它首先会生成自适应类的Java源码，然后再将源码编译成Java的字节码，加载到JVM中。</p>\n<pre><code class=\"language-java\"><span class=\"hljs-keyword\">private</span> Class<?> createAdaptiveExtensionClass() {\n String code = createAdaptiveExtensionClassCode();\n ClassLoader classLoader = findClassLoader();\n com.alibaba.dubbo.common.compiler.Compiler compiler = ExtensionLoader.getExtensionLoader(com.alibaba.dubbo.common.compiler.Compiler.class).getAdaptiveExtension();\n <span class=\"hljs-keyword\">return</span> compiler.compile(code, classLoader);\n }\n</code></pre>\n<p>Compiler的代码，默认实现是javassist。</p>\n<pre><code class=\"language-java\"><span class=\"hljs-meta\">@SPI</span>(<span class=\"hljs-string\">\"javassist\"</span>)\n<span class=\"hljs-keyword\">public</span> <span class=\"hljs-class\"><span class=\"hljs-keyword\">interface</span> <span class=\"hljs-title\">Compiler</span> </span>{\n Class<?> compile(String code, ClassLoader classLoader);\n}\n</code></pre>\n<p>createAdaptiveExtensionClassCode()方法中使用一个StringBuilder来构建自适应类的Java源码。方法实现比较长，这里就不贴代码了。这种生成字节码的方式也挺有意思的，先生成Java源代码，然后编译，加载到jvm中。通过这种方式，可以更好的控制生成的Java类。而且这样也不用care各个字节码生成框架的api等。因为xxx.java文件是Java通用的，也是我们最熟悉的。只是代码的可读性不强，需要一点一点构建xx.java的内容。\n下面是使用createAdaptiveExtensionClassCode方法为Protocol创建的自适应类的Java代码范例:</p>\n<pre><code class=\"language-java\"><span class=\"hljs-keyword\">package</span> com.alibaba.dubbo.rpc;\n\n<span class=\"hljs-keyword\">import</span> com.alibaba.dubbo.common.extension.ExtensionLoader;\n\n<span class=\"hljs-keyword\">public</span> <span class=\"hljs-class\"><span class=\"hljs-keyword\">class</span> <span class=\"hljs-title\">Protocol</span>$<span class=\"hljs-title\">Adpative</span> <span class=\"hljs-keyword\">implements</span> <span class=\"hljs-title\">com</span>.<span class=\"hljs-title\">alibaba</span>.<span class=\"hljs-title\">dubbo</span>.<span class=\"hljs-title\">rpc</span>.<span class=\"hljs-title\">Protocol</span> </span>{\n <span class=\"hljs-function\"><span class=\"hljs-keyword\">public</span> <span class=\"hljs-keyword\">void</span> <span class=\"hljs-title\">destroy</span><span class=\"hljs-params\">()</span> </span>{\n <span class=\"hljs-keyword\">throw</span> <span class=\"hljs-keyword\">new</span> UnsupportedOperationException(<span class=\"hljs-string\">\"method public abstract void com.alibaba.dubbo.rpc.Protocol.destroy() of interface com.alibaba.dubbo.rpc.Protocol is not adaptive method!\"</span>);\n }\n\n <span class=\"hljs-function\"><span class=\"hljs-keyword\">public</span> <span class=\"hljs-keyword\">int</span> <span class=\"hljs-title\">getDefaultPort</span><span class=\"hljs-params\">()</span> </span>{\n <span class=\"hljs-keyword\">throw</span> <span class=\"hljs-keyword\">new</span> UnsupportedOperationException(<span class=\"hljs-string\">\"method public abstract int com.alibaba.dubbo.rpc.Protocol.getDefaultPort() of interface com.alibaba.dubbo.rpc.Protocol is not adaptive method!\"</span>);\n }\n\n <span class=\"hljs-keyword\">public</span> com.alibaba.dubbo.rpc.<span class=\"hljs-function\">Exporter <span class=\"hljs-title\">export</span><span class=\"hljs-params\">(com.alibaba.dubbo.rpc.Invoker arg0)</span> <span class=\"hljs-keyword\">throws</span> com.alibaba.dubbo.rpc.RpcException </span>{\n <span class=\"hljs-keyword\">if</span> (arg0 == <span class=\"hljs-keyword\">null</span>) <span class=\"hljs-keyword\">throw</span> <span class=\"hljs-keyword\">new</span> IllegalArgumentException(<span class=\"hljs-string\">\"com.alibaba.dubbo.rpc.Invoker argument == null\"</span>);\n <span class=\"hljs-keyword\">if</span> (arg0.getUrl() == <span class=\"hljs-keyword\">null</span>)\n <span class=\"hljs-keyword\">throw</span> <span class=\"hljs-keyword\">new</span> IllegalArgumentException(<span class=\"hljs-string\">\"com.alibaba.dubbo.rpc.Invoker argument getUrl() == null\"</span>);\n com.alibaba.dubbo.common.URL url = arg0.getUrl();\n String extName = (url.getProtocol() == <span class=\"hljs-keyword\">null</span> ? <span class=\"hljs-string\">\"dubbo\"</span> : url.getProtocol());\n <span class=\"hljs-keyword\">if</span> (extName == <span class=\"hljs-keyword\">null</span>)\n <span class=\"hljs-keyword\">throw</span> <span class=\"hljs-keyword\">new</span> IllegalStateException(<span class=\"hljs-string\">\"Fail to get extension(com.alibaba.dubbo.rpc.Protocol) name from url(\"</span> + url.toString() + <span class=\"hljs-string\">\") use keys([protocol])\"</span>);\n com.alibaba.dubbo.rpc.Protocol extension = (com.alibaba.dubbo.rpc.Protocol) ExtensionLoader.getExtensionLoader(com.alibaba.dubbo.rpc.Protocol.class).getExtension(extName);\n <span class=\"hljs-keyword\">return</span> extension.export(arg0);\n }\n\n <span class=\"hljs-keyword\">public</span> com.alibaba.dubbo.rpc.<span class=\"hljs-function\">Invoker <span class=\"hljs-title\">refer</span><span class=\"hljs-params\">(java.lang.Class arg0, com.alibaba.dubbo.common.URL arg1)</span> <span class=\"hljs-keyword\">throws</span> com.alibaba.dubbo.rpc.RpcException </span>{\n <span class=\"hljs-keyword\">if</span> (arg1 == <span class=\"hljs-keyword\">null</span>) <span class=\"hljs-keyword\">throw</span> <span class=\"hljs-keyword\">new</span> IllegalArgumentException(<span class=\"hljs-string\">\"url == null\"</span>);\n com.alibaba.dubbo.common.URL url = arg1;\n String extName = (url.getProtocol() == <span class=\"hljs-keyword\">null</span> ? <span class=\"hljs-string\">\"dubbo\"</span> : url.getProtocol());\n <span class=\"hljs-keyword\">if</span> (extName == <span class=\"hljs-keyword\">null</span>)\n <span class=\"hljs-keyword\">throw</span> <span class=\"hljs-keyword\">new</span> IllegalStateException(<span class=\"hljs-string\">\"Fail to get extension(com.alibaba.dubbo.rpc.Protocol) name from url(\"</span> + url.toString() + <span class=\"hljs-string\">\") use keys([protocol])\"</span>);\n com.alibaba.dubbo.rpc.Protocol extension = (com.alibaba.dubbo.rpc.Protocol) ExtensionLoader.getExtensionLoader(com.alibaba.dubbo.rpc.Protocol.class).getExtension(extName);\n <span class=\"hljs-keyword\">return</span> extension.refer(arg0, arg1);\n }\n}\n</code></pre>\n<p>大致的逻辑和开始说的一样，通过url解析出参数，解析的逻辑由@Adaptive的value参数控制，然后再根据得到的扩展点名获取扩展点实现，然后进行调用。如果大家想知道具体的构建.java代码的逻辑，可以看<code>createAdaptiveExtensionClassCode</code>的完整实现。\n在生成的Protocol$Adpative中，发现getDefaultPort和destroy方法都是直接抛出异常的，这是为什么呢？来看看Protocol的源码</p>\n<pre><code class=\"language-java\"><span class=\"hljs-meta\">@SPI</span>(<span class=\"hljs-string\">\"dubbo\"</span>)\n<span class=\"hljs-keyword\">public</span> <span class=\"hljs-class\"><span class=\"hljs-keyword\">interface</span> <span class=\"hljs-title\">Protocol</span> </span>{\n\n <span class=\"hljs-function\"><span class=\"hljs-keyword\">int</span> <span class=\"hljs-title\">getDefaultPort</span><span class=\"hljs-params\">()</span></span>;\n\n <span class=\"hljs-meta\">@Adaptive</span>\n <T> <span class=\"hljs-function\">Exporter<T> <span class=\"hljs-title\">export</span><span class=\"hljs-params\">(Invoker<T> invoker)</span> <span class=\"hljs-keyword\">throws</span> RpcException</span>;\n\n <span class=\"hljs-meta\">@Adaptive</span>\n <T> <span class=\"hljs-function\">Invoker<T> <span class=\"hljs-title\">refer</span><span class=\"hljs-params\">(Class<T> type, URL url)</span> <span class=\"hljs-keyword\">throws</span> RpcException</span>;\n\n <span class=\"hljs-function\"><span class=\"hljs-keyword\">void</span> <span class=\"hljs-title\">destroy</span><span class=\"hljs-params\">()</span></span>;\n</code></pre>\n<p>可以看到Protocol接口中有4个方法，但只有export和refer两个方法使用了@Adaptive注解。Dubbo自动生成的自适应实例，只有@Adaptive修饰的方法才有具体的实现。所以，Protocol$Adpative类中，也只有export和refer这两个方法有具体的实现，其余方法都是抛出异常。</p>\n"
@@ -34,6 +38,10 @@
"filename": "dubbo-meetup-beijing-may-12th-2018.md",
"__html": "<h2>The first Dubbo meetup has been held in Beijing</h2>\n<p>The first Dubbo meetup has successfully been held in Beijing, over 400+ people were present. What a great event!</p>\n<p>Please enjoy the slides of the topics:</p>\n<ul>\n<li>Ian Luo: Dubbo's present and future (Chinese) <a href=\"https://github.com/dubbo/awesome-dubbo/raw/master/slides/meetup/201805%40Beijing/dubbo-present-and-future.pdf\">slides</a></li>\n<li>Jun Liu: Introduction to the 4th Aliware Performance Challenge (Chinese) <a href=\"https://github.com/dubbo/awesome-dubbo/raw/master/slides/meetup/201805%40Beijing/introduction-to-4th-aliware-performance-challenge.pdf\">slides</a></li>\n<li>Zhixuan Chen: Quickly building Microservice with Dubbo and Spring-boot (Chinese) <a href=\"https://github.com/dubbo/awesome-dubbo/raw/master/slides/meetup/201805%40Beijing/quickly-building-microservice-with-dubbo-and-springboot.pdf\">slides</a></li>\n<li>Xin Wang: Dubbo and Weidian's Practice on Microservice Architecture (Chinese) <a href=\"https://github.com/dubbo/awesome-dubbo/raw/master/slides/meetup/201805%40Beijing/dubbo-and-weidian's-practice-on-microservice-architecture.pdf\">slides</a></li>\n</ul>\n"
},
+ {
+ "filename": "dubbo-meetup-shanghai-jun-23rd-2018.md",
+ "__html": "<h2>Dubbo Shanghai meetup has been held successfully</h2>\n<p>The sencond Dubbo meetup has successfully been held in Shanghai, over 700 people submitted registration, and over 300 were present, more than 10,000 watched the live online. A great event again!</p>\n<p>Please enjoy the slides of the topics:</p>\n<ul>\n<li>Jerrick Zhu: Dubbo Status and Roadmap (Chinese) <a href=\"https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/dubbo-status-and-roadmap.pdf\">slides</a></li>\n<li>Mercy Ma: Dubbo Cloud Native Practices and Thoughts (Chinese) <a href=\"https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/dubbo-cloud-native-practices-and-thoughts.pdf\">slides</a></li>\n<li>Ping Guo: Nacos Open Source Initiative (Chinese) <a href=\"https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/nacos-open-source-initiative.pdf\">slides</a></li>\n<li>Zhiwei Pan: Dubbo Practices on Internet Finance Industries (Chinese) <a href=\"https://github.com/dubbo/awesome-dubbo/blob/master/slides/meetup/201806%40Shanghai/dubbo-practices-on-internet-finance-industries.pdf\">slides</a></li>\n</ul>\n"
+ },
{
"filename": "gsoc-2018.md",
"__html": "<h2>The GSoC(Google Summer of Code) 2018 projects has been announced</h2>\n<p>The GSoC(Google Summer of Code) 2018 projects has been announced, Raghu Reddy's project "Extending Serialization protocols support for Apache Dubbo" has been <a href=\"https://summerofcode.withgoogle.com/projects/#4747840161579008\">accepted</a>! Congratulations!</p>\n"
diff --git a/site_config/community.jsx b/site_config/community.jsx
index 0b77156..b066ebd 100644
--- a/site_config/community.jsx
+++ b/site_config/community.jsx
@@ -6,6 +6,13 @@ export default {
events: {
title: 'Events & News',
list: [
+ {
+ img: './img/blog/dubbo-shanghai-meetup.jpeg',
+ title: 'Dubbo Shanghai meetup has been held successfully',
+ content: 'The Dubbo meetup has successfully been held in Shanghai, over 700 people submitted registration, and over 300 were present, more than 10,000 watched the live online.',
+ dateStr: 'June 23rd，2018',
+ link: '/blog/dubbo-meetup-shanghai-jun-23rd-2018.md',
+ },
{
img: './img/blog/dubbo-beijing-meetup.png',
title: 'The first Dubbo meetup has successfully been held in Beijing',
@@ -364,6 +371,13 @@ export default {
events: {
title: '事件 & 新闻',
list: [
+ {
+ img: './img/blog/dubbo-shanghai-meetup.jpeg',
+ title: '第二届Dubbo开发者沙龙在上海成功举办',
+ content: '第二届Dubbo开发者沙龙在上海成功举办，超过700位开发者报名，现场参与人数300+，通过阿里云天池、云栖社区、大咖说引导线上直播观看次数10000+',
+ dateStr: 'Jun 23rd，2018',
+ link: '/blog/dubbo-meetup-shanghai-jun-23rd-2018.md',
+ },
{
img: './img/blog/dubbo-beijing-meetup.png',
title: '首届Dubbo开发者沙龙在北京成功举办',
----------------------------------------------------------------
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