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2016年4月21日
在Spring cloud config出來(lái)之前, 自己實(shí)現(xiàn)了基于ZK的配置中心, 杜絕了本地properties配置文件, 原理很簡(jiǎn)單, 只是重載了PropertyPlaceholderConfigurer的mergeProperties(): /** * 重載合并屬性實(shí)現(xiàn) * 先加載file properties, 然后并入ZK配置中心讀取的properties * * @return 合并后的屬性集合 * @throws IOException 異常 */ @Override protected Properties mergeProperties() throws IOException { Properties result = new Properties(); // 加載父類的配置 Properties mergeProperties = super.mergeProperties(); result.putAll(mergeProperties); // 加載從zk中讀取到的配置 Map<String, String> configs = loadZkConfigs(); result.putAll(configs); return result; } 這個(gè)實(shí)現(xiàn)在spring項(xiàng)目里用起來(lái)還是挺順手的, 但是近期部分spring-boot項(xiàng)目里發(fā)現(xiàn)這種placeholder的實(shí)現(xiàn)跟spring boot的@ConfigurationProperties(prefix = "xxx") 不能很好的配合工作, 也就是屬性沒(méi)有被resolve處理, 用@Value的方式確可以讀到, 但是@Value配置起來(lái)如果屬性多的話還是挺繁瑣的, 還是傾向用@ConfigurationProperties的prefix, 于是看了下spring boot的文檔發(fā)現(xiàn) PropertySource order: * Devtools global settings properties on your home directory (~/.spring-boot-devtools.properties when devtools is active). * @TestPropertySource annotations on your tests. * @SpringBootTest#properties annotation attribute on your tests. * Command line arguments. * Properties from SPRING_APPLICATION_JSON (inline JSON embedded in an environment variable or system property) * ServletConfig init parameters. * ServletContext init parameters. * JNDI attributes from java:comp/env. * Java System properties (System.getProperties()). * OS environment variables. * A RandomValuePropertySource that only has properties in random.*. * Profile-specific application properties outside of your packaged jar (application-{profile}.properties and YAML variants) * Profile-specific application properties packaged inside your jar (application-{profile}.properties and YAML variants) * Application properties outside of your packaged jar (application.properties and YAML variants). * Application properties packaged inside your jar (application.properties and YAML variants). * @PropertySource annotations on your @Configuration classes. * Default properties (specified using SpringApplication.setDefaultProperties). 不難發(fā)現(xiàn)其會(huì)檢查Java system propeties里的屬性, 也就是說(shuō), 只要把mergerProperties讀到的屬性寫入Java system props里即可, 看了下源碼, 找到個(gè)切入點(diǎn) /** * 重載處理屬性實(shí)現(xiàn) * 根據(jù)選項(xiàng), 決定是否將合并后的props寫入系統(tǒng)屬性, Spring boot需要 * * @param beanFactoryToProcess * @param props 合并后的屬性 * @throws BeansException */ @Override protected void processProperties(ConfigurableListableBeanFactory beanFactoryToProcess, Properties props) throws BeansException { // 原有邏輯 super.processProperties(beanFactoryToProcess, props); // 寫入到系統(tǒng)屬性 if (writePropsToSystem) { // write all properties to system for spring boot Enumeration<?> propertyNames = props.propertyNames(); while (propertyNames.hasMoreElements()) { String propertyName = (String) propertyNames.nextElement(); String propertyValue = props.getProperty(propertyName); System.setProperty(propertyName, propertyValue); } } } 為避免影響過(guò)大, 設(shè)置了個(gè)開(kāi)關(guān), 是否寫入系統(tǒng)屬性, 如果是spring boot的項(xiàng)目, 就開(kāi)啟, 這樣對(duì)線上非spring boot項(xiàng)目做到影響最小, 然后spring boot的@ConfigurationProperties完美讀到屬性; 具體代碼見(jiàn): org.springframework.boot.context.properties.ConfigurationPropertiesBindingPostProcessor @Override public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { ConfigurationProperties annotation = AnnotationUtils .findAnnotation(bean.getClass(), ConfigurationProperties.class); if (annotation != null) { postProcessBeforeInitialization(bean, beanName, annotation); } annotation = this.beans.findFactoryAnnotation(beanName, ConfigurationProperties.class); if (annotation != null) { postProcessBeforeInitialization(bean, beanName, annotation); } return bean; }
Spring默認(rèn)不允許對(duì)類的變量, 也就是靜態(tài)變量進(jìn)行注入操作, 但是在某些場(chǎng)景比如單元測(cè)試的@AfterClass要訪問(wèn)注入對(duì)象, 而Junit的這個(gè)方法必須是靜態(tài)的, 也就產(chǎn)生了悖論; 解決思路有兩個(gè): 思路1: 想辦法對(duì)靜態(tài)變量注入, 也就是繞過(guò)Spring只能運(yùn)行非靜態(tài)變量才能注入依賴的壁壘 思路2: 想辦法@AfterClass改造為非靜態(tài) 實(shí)現(xiàn)Junit RunListener, 覆蓋testRunFinished方法, 這里去實(shí)現(xiàn)類似@AfterClass的功能, 這個(gè)方法是非靜態(tài)的 不要用Junit, 改用TestNG, TestNG里的AfterClass是非靜態(tài)的 用Spring的TestExecutionListeners, 實(shí)現(xiàn)個(gè)Listener, 里面也有個(gè)類似非靜態(tài)的AfterClass的實(shí)現(xiàn), 覆蓋實(shí)現(xiàn)就行
思路2的幾個(gè)方法都可以實(shí)現(xiàn), 但是單元測(cè)試Runner需要用 而且改用TestNG工程浩大, 只能放棄掉這個(gè)思路 繼續(xù)走思路1, 只能去繞過(guò)Spring的依賴注入的static壁壘了, 具體代碼如下: @Autowired private Destination dfsOperationQueue; private static Destination dfsOperationQueueStatic; // static version @Autowired private MessageQueueAPI messageQueueAPI; private static MessageQueueAPI messageQueueAPIStatic; // static version
@PostConstruct public void init() { dfsOperationQueueStatic = this.dfsOperationQueue; messageQueueAPIStatic = this.messageQueueAPI; }
@AfterClass public static void afterClass() { MessageVO messageVO = messageQueueAPIStatic.removeDestination(dfsOperationQueueStatic); System.out.println(messageVO); }
其實(shí)就是用了@PostConstruct 來(lái)個(gè)偷梁換柱而已, 多聲明個(gè)靜態(tài)成員指向非靜態(tài)對(duì)象, 兩者其實(shí)是一個(gè)對(duì)象
知道activemq現(xiàn)在已經(jīng)支持了rest api, 但是官方對(duì)這部分的介紹一筆帶過(guò) (http://activemq.apache.org/rest.html),
通過(guò)google居然也沒(méi)搜到一些有用的, 比如像刪除一個(gè)destination, 都是問(wèn)的多,然后沒(méi)下文. 于是花了一些心思研究了一下:
首先通過(guò)rest api獲取當(dāng)前版本所有已支持的協(xié)議 http://172.30.43.206:8161/api/jolokia/list
然后根據(jù)json輸出關(guān)于removeTopic, removeQueue的mbean實(shí)現(xiàn)通過(guò)rest api刪除destination的方法, 注意到用GET請(qǐng)求而不是POST,不然會(huì)報(bào)錯(cuò) (官網(wǎng)的例子里用的wget給的靈感, 開(kāi)始用了POST老報(bào)錯(cuò))
import org.apache.activemq.command.ActiveMQQueue; import org.apache.activemq.command.ActiveMQTopic; import org.apache.http.auth.AuthScope; import org.apache.http.auth.UsernamePasswordCredentials; import org.apache.http.impl.client.BasicCredentialsProvider; import org.apache.http.impl.client.DefaultHttpClient; import org.springframework.http.HttpEntity; import org.springframework.http.HttpHeaders; import org.springframework.http.HttpMethod; import org.springframework.http.MediaType; import org.springframework.http.ResponseEntity; import org.springframework.http.client.ClientHttpRequestFactory; import org.springframework.http.client.HttpComponentsClientHttpRequestFactory; import org.springframework.web.client.RestTemplate;
import javax.jms.Destination; import javax.jms.JMSException; import java.util.Arrays;
public class MessageQueueAdmin { private static final RestTemplate restTemplate = getRestTemplate("admin", "admin");
private static String brokerHost = "172.30.43.206"; private static String adminConsolePort = "8161"; private static String protocol = "http";
public static void removeDestination(Destination destination) throws JMSException { String destName, destType; if (destination instanceof ActiveMQQueue) { destName = ((ActiveMQQueue) destination).getQueueName(); destType = "Queue"; } else { destName = ((ActiveMQTopic) destination).getTopicName(); destType = "Topic"; }
// build urls String url = String.format("%s://%s:%s/api/jolokia/exec/org.apache.activemq:" + "brokerName=localhost,type=Broker/remove%s/%s", protocol, brokerHost, adminConsolePort, destType, destName); System.out.println(url); // do operation HttpHeaders headers = new HttpHeaders(); headers.setAccept(Arrays.asList(MediaType.APPLICATION_JSON)); HttpEntity<String> entity = new HttpEntity<String>("parameters", headers); ResponseEntity response = restTemplate.exchange(url, HttpMethod.GET, entity, String.class); System.out.println(response.getBody()); }
public static void main(String[] args) throws JMSException { ActiveMQTopic topic = new ActiveMQTopic("test-activemq-topic"); removeDestination(topic); }
private static RestTemplate getRestTemplate(String user, String password) { DefaultHttpClient httpClient = new DefaultHttpClient(); BasicCredentialsProvider credentialsProvider = new BasicCredentialsProvider(); credentialsProvider.setCredentials(AuthScope.ANY, new UsernamePasswordCredentials(user, password)); httpClient.setCredentialsProvider(credentialsProvider); ClientHttpRequestFactory rf = new HttpComponentsClientHttpRequestFactory(httpClient);
return new RestTemplate(rf); } }
其他的請(qǐng)求,應(yīng)該都是類似jolokia的exec get request的格式:
https://jolokia.org/reference/html/protocol.html#exec
<base url>/exec/<mbean name>/<operation name>/<arg1>/<arg2>/ .
用Spring JMS 的JmsTemplate從消息隊(duì)列消費(fèi)消息時(shí)發(fā)現(xiàn),使用了CLIENT_ACKNOWLEDGE模式,消息返回后總是自動(dòng)被ack,也就是被broker "Dequeued" protected Message doReceive(Session session, MessageConsumer consumer) throws JMSException { try { // Use transaction timeout (if available). long timeout = getReceiveTimeout(); JmsResourceHolder resourceHolder = (JmsResourceHolder) TransactionSynchronizationManager.getResource(getConnectionFactory()); if (resourceHolder != null && resourceHolder.hasTimeout()) { timeout = Math.min(timeout, resourceHolder.getTimeToLiveInMillis()); } Message message = doReceive(consumer, timeout); if (session.getTransacted()) { // Commit necessary - but avoid commit call within a JTA transaction. if (isSessionLocallyTransacted(session)) { // Transacted session created by this template -> commit. JmsUtils.commitIfNecessary(session); } } else if (isClientAcknowledge(session)) { // Manually acknowledge message, if any. if (message != null) { message.acknowledge(); } } return message; } finally { JmsUtils.closeMessageConsumer(consumer); } }
但是使用異步listener 就不會(huì)出現(xiàn)這個(gè)情況,搜了下google,發(fā)現(xiàn)果然存在這個(gè)問(wèn)題 https://jira.spring.io/browse/SPR-12995 https://jira.spring.io/browse/SPR-13255 http://louisling.iteye.com/blog/241073 同步方式拉取消息,暫時(shí)沒(méi)找到好的封裝,只能暫時(shí)用這。或者盡量用listener, 這個(gè)問(wèn)題暫時(shí)標(biāo)記下,或者誰(shuí)有更好的解決方案可以comment我
默認(rèn)的配置有時(shí)候點(diǎn)不亮顯示器,且分辨率很低,通過(guò)tvservice工具不斷調(diào)試,發(fā)現(xiàn)下面的參數(shù)可以完美匹配了 修改 /boot/config.txt的下列參數(shù) disable_overscan=1 hdmi_force_hotplug=1 hdmi_group=1 hdmi_mode=16 hdmi_drive=2 config_hdmi_boost=4 dtparam=audio=on
http://stackoverflow.com/questions/3294423/spring-classpath-prefix-difference
SIMPLE DEFINITION
The classpath*:conf/appContext.xml simply means that all appContext.xml files under conf folders in all your jars on the classpath will be picked up and joined into one big application context.
In contrast, classpath:conf/appContext.xml will load only one such file the first one found on your classpath.
<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer"> <property name="locations"> <list> <value>classpath:*.properties</value> <value>classpath*:*.properties</value> </list> </property> </bean>
- IDEA_JDK (or IDEA_JDK_64) environment variable
- jre/ (or jre64/) directory in IDEA home
- registry
- JDK_HOME environment variable
- JAVA_HOME environment variable
java里如何修改console的歷史輸出信息呢?如果是當(dāng)前行的修改可以簡(jiǎn)單想到"\r"的方案,但是如果要修改上一行呢? google了下原來(lái)還是有方法的,需要用到ansi的control sequences ANSI code用java寫了個(gè)簡(jiǎn)單的例子,例子就是把曾經(jīng)的output修改為其他字符串并恢復(fù)之后的打印,代碼里加了sleep,主要方便理解各種控制序列的含義 //print some test messages System.out.println("1"); Thread.sleep(1000); System.out.println("22"); Thread.sleep(1000); System.out.println("333"); Thread.sleep(1000); System.out.println("4444"); Thread.sleep(1000);
/** * modify "333" to "-" */ // Move up two lines int count = 2; System.out.print(String.format("\033[%dA", count)); Thread.sleep(1000); // Erase current line content System.out.print("\033[2K"); Thread.sleep(1000); // update with new content System.out.print("-"); Thread.sleep(1000); // Move down two lines System.out.print(String.format("\033[%dB", count)); Thread.sleep(1000); // Move cursor to left beginning System.out.print(String.format("\033[D", count)); // continue print others Thread.sleep(1000); System.out.println("55555"); Thread.sleep(1000);
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