Spring Boot

SpringBoot

WhoAmI?

• Youwillfindmeherehttps://github.com/tan9

http://stackoverflow.com/users/3440376/tan9

• MyJavaexperience• JavaandJavaEEdevelopment– 8+years• SpringFramework– 6+years• SpringBoot– 1.5years

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BeforeWe Get Started…

• Jointhechannel:http://bit.do/spring-boot• Directlink:https://gitter.im/tan9/spring-boot-training

• SigninusingyourGitHub account• Orsignuprightnow!

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SpringFramework

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SpringFramework

• InversionofControl(IoC)container• DependencyInjection(DI)• Beanlifecyclemanagement• Aspect-OrientedProgramming(AOP)

• “Plumbing”ofenterprisefeatures• MVCw/RESTful,TX,JDBC,JPA,JMS…

• Neutral• Doesnotimposeanyspecificprogrammingmodel.• Supportsvariousthird-partylibraries.

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Spring2.5JavaConfig

• FavorJavaAnnotation (introducedinJavaSE5)• @Controller, @Service and@Repository• @Autowired

• ThinXMLconfigurationfile

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<context:annotation-config/><context:component-scan

base-package="com.cht"/>

JavaConfig KeepEvolving

• @Bean&@Configuration since3.0• GetridofXMLconfigurationfiles.

• @ComponentScan,@Enable* and@Profile since3.1• WithWebApplicationInitializer poweredbyServlet3,saygoodbyetoweb.xml too.

• @Conditional since4.0• We’reabletofilterbeansprogrammatically.

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MavenBill-Of-Materials(BOM)

• KeeplibraryversionsinONEplace.• ImportfromPOM’s<dependencyManagement>section.

• Declaredependencies without<version>:

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<dependency><groupId>org.springframework</groupId><artifactId>spring-context</artifactId>

</dependency>

Things GettingComplicated

• Springseldomdeprecatesanything• Andofferslittleopinionorguidance.• Olderapproachesremainatthetopinsearchresults.

• Bootstrappingcanbepainful• Duetothesheersizeandgrowthrateoftheportfolio.

• Springisanincrediblypowerfultool…• Onceyougetitsetup.

Shouldyouusespringboot inyournextproject?- StevePerkinshttps://steveperkins.com/use-spring-boot-next-project/ 9

SpringBoot

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ThoughtWorks TechnologyRadar

11ThoughtWorks Techonlogy RaderApril‘16https://www.thoughtworks.com/radar

SpringBoot

• Opinionated• Convention overconfiguration.

• Production-readynon-functionalfeatures• Embeddedservers,security,metrics,healthchecks…

• Speedup• Designedtogetyouupandrunningasquicklyaspossible.

• PlainJava• NocodegenerationandnoXMLconfiguration.

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SystemRequirements

• SpringBoot1.3requiresJava7+ bydefault• Java8isrecommendedifatallpossible.• CanusewithJava6withsomeadditionalconfiguration.

• Servlet3.0+ container• Embedded Tomcat7+,Jetty8+,Undertow1.1+.• OracleWebLogicServer12corlater.• IBMWebSphereApplicationServer8.5orlater.• JBoss EAP6orlater.

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BootWithApacheM

aven

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<project><modelVersion>4.0.0</modelVersion><groupId>com.cht</groupId><artifactId>inception</artifactId><version>0.0.1-SNAPSHOT</version>

<parent>

<groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>1.3.5.RELEASE</version>

</parent>

<dependencies>

<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-web</artifactId>

</dependency></dependencies>

<build>

<plugins><plugin>

<groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId>

</plugin></plugins>

</build></project>

StarterPOMs

• Makeeasytoaddjarstoyourclasspath.• spring-boot-starter-parent• ProvidesusefulMavendefaults.• Definesversion tagsfor“blessed”dependencies.

• spring-boot-starter-*• Providesdependenciesyouarelikelytoneedfor*.

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FirstClass

package com.cht.inception;

import org.springframework.boot.*;import org.springframework.boot.autoconfigure.*;import org.springframework.web.bind.annotation.*;

@RestController@EnableAutoConfigurationpublic class Application {

@RequestMapping("/")String home() {

return "Hello World!";}

public static void main(String[] args) {SpringApplication.run(Application.class, args);

}}

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mvn spring-boot:run

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. ____ _ __ _ _/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \\\/ ___)| |_)| | | | | || (_| | ) ) ) )' |____| .__|_| |_|_| |_\__, | / / / /

=========|_|==============|___/=/_/_/_/:: Spring Boot :: (v1.3.5.RELEASE)

2016-07-03 23:38:04.683 INFO 93490 --- [ main] com.cht.inception.Application : Starting Application on Huangs-MBP with PID 93490 (/Users/tang/Desktop/spring-boot-training/target/classes started by tang in /Users/tang/Desktop/spring-boot-training)2016-07-03 23:38:04.685 INFO 93490 --- [ main] com.cht.inception.Application : No active profile set, falling back to default profiles: default2016-07-03 23:38:04.718 INFO 93490 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@63f60873: startup date [Sun Jul 03 23:38:04 CST 2016]; root of context hierarchy2016-07-03 23:38:05.482 INFO 93490 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)2016-07-03 23:38:05.491 INFO 93490 --- [ main] o.apache.catalina.core.StandardService : Starting service Tomcat2016-07-03 23:38:05.491 INFO 93490 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.0.332016-07-03 23:38:05.548 INFO 93490 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext2016-07-03 23:38:05.548 INFO 93490 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 833 ms2016-07-03 23:38:05.702 INFO 93490 --- [ost-startStop-1] o.s.b.c.e.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/]2016-07-03 23:38:05.705 INFO 93490 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]2016-07-03 23:38:05.705 INFO 93490 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]2016-07-03 23:38:05.705 INFO 93490 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]2016-07-03 23:38:05.705 INFO 93490 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]2016-07-03 23:38:05.833 INFO 93490 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@63f60873: startup date [Sun Jul 03 23:38:04 CST 2016]; root of context hierarchy2016-07-03 23:38:05.876 INFO 93490 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/]}" onto java.lang.String com.cht.inception.Application.home()2016-07-03 23:38:05.879 INFO 93490 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)2016-07-03 23:38:05.879 INFO 93490 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)2016-07-03 23:38:05.898 INFO 93490 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2016-07-03 23:38:05.898 INFO 93490 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2016-07-03 23:38:05.921 INFO 93490 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]2016-07-03 23:38:05.986 INFO 93490 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup2016-07-03 23:38:06.032 INFO 93490 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)2016-07-03 23:38:06.036 INFO 93490 --- [ main] com.cht.inception.Application : Started ⏎Application in 1.529 seconds (JVM running for 4.983)

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ApplicationProperties

• Placeapplication.yaml inclasspath• Forexample:• Configuringembeddedservercanbeaseasyas:

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server:address: 127.0.0.1port: 5566

YAML(YAMLAin’t MarkupLanguage)

• SupersetofJSON.• UTF-8!• Reallygoodforhierarchicalconfigurationdata.

• But…can'tbeloadedviathe@PropertySource.

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my:servers:

- dev.bar.com- foo.bar.com

my.servers[0]=dev.bar.commy.servers[1]=foo.bar.com

YAML

JavaProperties

ExecutableJAR

• $ mvn package• Buildandpackagetheproject.• SpringBootwillrepackageitintoanexecutableone.

• $ java -jar target/\inception-0.0.1-SNAPSHOT.jar• It’sjustrunning.• Thejariscompletelyself-contained,youcandeployandrunitanywhere(withJava).

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SpringBoot:Dev

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QuickStart

• SpringInitializrWebService• http://start.spring.io

• SpringSource ToolsSuite(eclipse-based)• https://spring.io/tools/sts/all

• IntelliJIDEAUltimate(Costs$$$)• https://www.jetbrains.com/idea/• OrimportSpringInitializr generatedprojectfromIntelliJIDEACommunityEdition.

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DeveloperTools

• Setdevproperties,likedisablingcache.• Automaticrestart whenresourceschanged.• LiveReload thebrowser.• Remoteupdateanddebug.

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<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-devtools</artifactId><optional>true</optional>

</dependency>

ExternalizedConfiguration

1. Commandlinearguments.2. Propertiesfrom SPRING_APPLICATION_JSON.3. JNDIattributesfrom java:comp/env.4. JavaSystemproperties(System.getProperties()).5. OSenvironmentvariables.6. RandomValuePropertySource forrandom.*.7. Applicationpropertyfiles.8. @PropertySource [email protected]. SpringApplication.setDefaultProperties().

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ApplicationPropertyFilesLookup

• ProfileandFileTypePriority1. application-{profile|default}.properties/.yml /.yaml2. application.properties/.yml /.yaml

• LocationPriority1. A/config subdirectoryofthecurrentdirectory.2. Thecurrentdirectory.3. Aclasspath /config package.4. Theclasspath root.

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PropertyNameRelaxedBinding

Property Noteperson.firstName Standardcamelcasesyntax.person.first-name Dashednotation,recommended

forusein.propertiesand.yml files.person.first_name Underscorenotation,alternative

formatforusein.propertiesand.yml files.

PERSON_FIRST_NAME Uppercaseformat.Recommendedwhenusingasystemenvironmentvariables.

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@ConfigurationProperties

• ItisType-safe.• Moreclearandexpressivethan@Value("{connection.username}")

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@lombok.Data@Component@ConfigurationProperties(prefix = "connection")public class ConnectionProperties {

private String username = "anonymous";@NotNullprivate InetAddress remoteAddress;

}

IncorporateOur@Configurations

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@Configuration@EnableAutoConfiguration@ComponentScanpublic @interface SpringBootApplication {

...}

@Order(Ordered.LOWEST_PRECEDENCE - 1)public class EnableAutoConfigurationImportSelectorimplements DeferredImportSelector...

ConfigurationOverrideConvention• Alwayslookupthepropertieslistfirst• http://docs.spring.io/spring-boot/docs/current/reference/html/common-application-properties.html

• Write@Configurationsand@Beansifneeded• Then@ComponentScan themin.• That’swhatyouarereallygoodat.

• AutoConfigurations justservesasafallback.

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SpringBoot:Run

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SpringBootActuator

“Anactuatorisamanufacturingterm,referringtoamechanicaldeviceformovingorcontrollingsomething.Actuatorscangeneratealargeamountofmotionfromasmallchange.”

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<dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-actuator</artifactId>

</dependency>

Production-ReadyEndpoints

• SpringConfiguration• autoconfig,beans,configprops,env andmappings

• Logging&stats• logfile,metrics,trace

• Informational• dump,info,flyway,liquibase

• Operational• shutdown

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HealthInformation

• BeansimplementsHealthIndicator• Youcan@Autowired whatyouneedforhealthchecking.• Resultwillbecachedfor1secondsbydefault.

• Out-of-the-boxindicators• Application,DiskSpace,DataSource,Mail,Redis,Elasticsearch,Jms,Cassandra,Mongo,Rabbit,Solr…

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Metrics

• Gauge• recordsasinglevalue.

• Counter• recordsadelta(anincrementordecrement).

• PublicMetrics• Exposemetricsthatcannotberecordviaoneofthosetwomechanisms.

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SpringBoot:ExtCustomAutoConfigurationsandConfigurtaionProperties

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AutoConfiguration

• META-INF/spring.factories

• Nothingspecialbut@Configuration.• SpringBootwillthenevaluateallAutoConfigurationavailablewhenbootstrapping.

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# Auto Configureorg.springframework.boot.autoconfigure.EnableAutoConfiguration=\com.cht.inception.autoconfigure.DemoAutoConfiguration

@ConditionalOn*

• Eliminatingall@Configurationwillnotwork.• Knowingandusingbuilt-inswherepossible• @ConditionalOnBean• @ConditionalOnClass• @ConditionalOnMissingBean• @ConditionalOnMissingClass• @ConditionalOnProperty• …andmore

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@Order matters

• HintsforSpringBoot• @AutoConfigureAfter• @AutoConfigureBefore

• Youstillhavetoknowwhatunderlying• Noteveryoperationisidempotentorcumulative.• WebSecurityConfigurerAdapter forexample.

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@ConfigurationProperties

• Naming thingsseriously• There are only two hard things in Computer Science:

cache invalidation and naming things. -- Phil Karlton• Itwillbeanimportantpartofyourownframework!

• Generatespropertiesmetadataatcompiletime• LocatedatMETA-INF/spring-configuration-metedata.json.• ASpringBoot-awareIDEwillbegreathelpforyou.

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Deploying

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PackageasWAR

• POM.xml• <packaging>war</packaging>

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@SpringBootApplicationpublic class Application

extends SpringBootServletInitializerimplements WebApplicationInitializer {

...}

JBoss EAP

• JBoss EAPv6.0– 6.2• Havetoremoveembeddedserver.

• JBoss EAPv6.x• spring.jmx.enabled=false• server.servlet-path=/*

• http://stackoverflow.com/a/1939642• Multipartrequestcharsetencodingvalueiswrong.• HavetodowngradeJPAandHibernate.

• JBoss EAPv7• Haven’ttriedyet.

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OracleWebLogicServer

• WebLogic11gandbelow• Notsupported.

• WebLogic12c• FilterregistrationlogicisWRONG!

• https://github.com/spring-projects/spring-boot/issues/2862#issuecomment-99461807

• Havetoremoveembeddedserver.• HavetodowngradeJPAandHibernate.• Havetospecify<wls:prefer-application-packages/> inweblogic.xml.

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IBMWebSphereAS

• WebSphereASv8.5.5• Havetoremoveembeddedserver.• HavetodowngradeJPAandHibernate.

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What’sNext?

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TryJHipsterhttps://jhipster.github.io/

andtolearnsomethingfromhim.

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References

• IntroductiontoSpringBoot- DaveSyer,PhilWebb• http://presos.dsyer.com/decks/spring-boot-intro.html

• SpringBootReferenceGuide• http://docs.spring.io/spring-boot/docs/current/

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