这篇文章主要介绍了SpringBoot 中 AutoConfiguration的使用方法，本文通过实例代码给大家介绍的非常详细，具有一定的参考借鉴价值,需要的朋友可以参考下
在SpringBoot中我们经常可以引入一些starter包来集成一些工具的使用,比如spring-boot-starter-d来源gaodaima#com搞(代@码网ata-redis。
使用起来很方便,那么是如何实现的呢?
代码分析
我们先看注解@SpringBootApplication,它里面包含一个@EnableAutoConfiguration
继续看@EnableAutoConfiguration注解
@Import({AutoConfigurationImportSelector.class})
在这个类(AutoConfigurationImportSelector)里面实现了自动配置的加载
主要代码片段:
String[] selectImports(AnnotationMetadata annotationMetadata)方法中
AutoConfigurationImportSelector.AutoConfigurationEntry autoConfigurationEntry = this.getAutoConfigurationEntry(autoConfigurationMetadata, annotationMetadata);
getAutoConfigurationEntry方法中:
List configurations = this.getCandidateConfigurations(annotationMetadata, attributes); protected List getCandidateConfigurations(AnnotationMetadata metadata, AnnotationAttributes attributes) { List configurations = SpringFactoriesLoader.loadFactoryNames(this.getSpringFactoriesLoaderFactoryClass(), this.getBeanClassLoader()); Assert.notEmpty(configurations, "No auto configuration classes found in META-INF/spring.factories. If you are using a custom packaging, make sure that file is correct."); return configurations; }
最后会通过SpringFactoriesLoader.loadSpringFactories去加载META-INF/spring.factories
Enumeration urls = classLoader != null ? classLoader.getResources("META-INF/spring.factories") : ClassLoader.getSystemResources("META-INF/spring.factories"); LinkedMultiValueMap result = new LinkedMultiValueMap();
while(urls.hasMoreElements()) { URL url = (URL)urls.nextElement(); UrlResource resource = new UrlResource(url); Properties properties = PropertiesLoaderUtils.loadProperties(resource); Iterator var6 = properties.entrySet().iterator(); while(var6.hasNext()) { Entry entry = (Entry)var6.next(); String factoryClassName = ((String)entry.getKey()).trim(); String[] var9 = StringUtils.commaDelimitedListToStringArray((String)entry.getValue()); int var10 = var9.length; for(int var11 = 0; var11 <var10; ++var11) { String factoryName = var9[var11]; result.add(factoryClassName, factoryName.trim()); } } }
ZookeeperAutoConfiguration
我们来实现一个ZK的AutoConfiguration
首先定义一个ZookeeperAutoConfiguration类
然后在META-INF/spring.factories中加入
org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.fayayo.fim.zookeeper.ZookeeperAutoConfiguration
接下来我们看看具体的实现:
@ConfigurationProperties(prefix = "fim.register") @Configuration public class URLRegistry { private String address; private int timeout; private int sessionTimeout; public String getAddress() { if (address == null) { address = URLParam.ADDRESS; } return address; } public void setAddress(String address) { this.address = address; } public int getTimeout() { if (timeout == 0) { timeout = URLParam.CONNECTTIMEOUT; } return timeout; } public void setTimeout(int timeout) { this.timeout = timeout; } public int getSessionTimeout() { if (sessionTimeout == 0) { sessionTimeout = URLParam.REGISTRYSESSIONTIMEOUT; } return sessionTimeout; } public void setSessionTimeout(int sessionTimeout) { this.sessionTimeout = sessionTimeout; } } @Configuration @EnableConfigurationProperties(URLRegistry.class) @Slf4j public class ZookeeperAutoConfiguration { @Autowired private URLRegistry url; @Bean(value = "registry") public Registry createRegistry() { try { String address = url.getAddress(); int timeout = url.getTimeout(); int sessionTimeout = url.getSessionTimeout(); log.info("init ZookeeperRegistry,address[{}],sessionTimeout[{}],timeout[{}]", address, timeout, sessionTimeout); ZkClient zkClient = new ZkClient(address, sessionTimeout, timeout); return new ZookeeperRegistry(zkClient); } catch (ZkException e) { log.error("[ZookeeperRegistry] fail to connect zookeeper, cause: " + e.getMessage()); throw e; } } }
ZookeeperRegistry部分实现:
public ZookeeperRegistry(ZkClient zkClient) { this.zkClient = zkClient; log.info("zk register success!"); String parentPath = URLParam.ZOOKEEPER_REGISTRY_NAMESPACE; try { if (!zkClient.exists(parentPath)) { log.info("init zookeeper registry namespace"); zkClient.createPersistent(parentPath, true); } //监听 zkClient.subscribeChildChanges(parentPath, new IZkChildListener() { //对父节点添加监听子节点变化。 @Override public void handleChildChange(String parentPath, List currentChilds) { log.info(String.format("[ZookeeperRegistry] service list change: path=%s, currentChilds=%s", parentPath, currentChilds.toString())); if(watchNotify!=null){ watchNotify.notify(nodeChildsToUrls(currentChilds)); } } }); ShutDownHook.registerShutdownHook(this); } catch (Exception e) { e.printStackTrace(); log.error("Failed to subscribe zookeeper"); } }
具体使用
那么我们怎么使用自己写的ZookeeperAutoConfiguration呢
首先要在需要使用的项目中引入依赖
com.fayayofim-registry-zookeeper0.0.1-SNAPSHOT
然后配置参数
fim: register: address: 192.168.88.129:2181 timeout: 2000
如果不配置会有默认的参数
具体使用的时候只需要在Bean中注入就可以了,比如
@Autowired private Registry registry; public List getAll(){ Listlist=cache.get(KEY); if(CollectionUtils.isEmpty(list)){ list=registry.discover(); cache.put(KEY,list); } return list; }
完整代码
https://github.com/lizu18xz/fim.git
总结
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转载请注明原文链接：SpringBoot 中 AutoConfiguration的使用方法
转载请注明原文链接：SpringBoot 中 AutoConfiguration的使用方法
