Spring Boot
SpringBoot是一个社区反馈推动的项目。SpringBoot可以说是至少五年来Spring乃至整个Java社区最有影响力的项目之一。SpringBoot主要包括以下特性：
- 直接嵌入Tomcat，Jetty或者Undertow作为Servlet container。从此之后再也不用将应用程序打包成war然后上传到application server里面了。
- 提供了starter POM，能够非常方便的进行包管理，很大程度上减少了jar hell或者dependency hell。
- 自动进行Spring框架的配置，节省程序员大量的时间和精力，能够让程序员专注在业务逻辑代码的编写上。
- 不需要任何第三方系统，Spring Boot自带了可以用于生产环境的程序状态信息和健康状态。同时可以让应用程序非常方便的读取外部的配置信息。
- 完全不需要任何代码的自动生成。更不需要用xml来进行框架配置。
基于Maven工程使用SpringBoot
新建Maven工程，编写pom.xml
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion> <groupId>20171111</groupId>
<artifactId>springboot</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging> <name>springboot</name>
<url>http://maven.apache.org</url> <parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.3.2.RELEASE</version>
<relativePath></relativePath>
</parent>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties> <dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
<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>
编写main函数：
在这里标记HelloworldDemoApplication class为SpringBootApplication，SpringBoot在后台会根据这个标记进行很多自动配置，比如配置MVC，配置包扫描，注入必要的类，注入自动配置的类等等。
这里的main函数是一个java标准的main函数，这个相当于应用程序入口，servlet container会在启动的时候找到这个入口，启动Spring container，完成初始化。
package springboot; import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.embedded.ConfigurableEmbeddedServletContainer;
import org.springframework.boot.context.embedded.EmbeddedServletContainerCustomizer; @SpringBootApplication
public class HelloworldDemoApplication implements EmbeddedServletContainerCustomizer{
public static void main(String[] args){
SpringApplication.run(HelloworldDemoApplication.class, args);
} public void customize(ConfigurableEmbeddedServletContainer container) {
// TODO 自动生成的方法存根
container.setPort(8088);
}
}
编写 HelloworldRestController类
package springboot; import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController; @RestController
public class HelloworldRestController {
@RequestMapping("/")
public String helloworld(){
return "hello world";
}
}
选择运行方式为：Maven Build ->对应的窗口里面设置Goals：clean package spring-boot:run，顺便为了方便把下面的Skip Tests也勾上，然后run。
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v1.3.2.RELEASE) 2017-11-11 23:41:56.105 INFO 8407 --- [ main] springboot.HelloworldDemoApplication : Starting HelloworldDemoApplication on pdeMacBook-Pro.local with PID 8407 (/Users/pg/Documents/workspace/springboot/target/classes started by pg in /Users/pg/Documents/workspace/springboot)
2017-11-11 23:41:56.107 INFO 8407 --- [ main] springboot.HelloworldDemoApplication : No active profile set, falling back to default profiles: default
2017-11-11 23:41:56.147 INFO 8407 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@563b3f89: startup date [Sat Nov 11 23:41:56 CST 2017]; root of context hierarchy
2017-11-11 23:41:57.262 INFO 8407 --- [ main] o.s.b.f.s.DefaultListableBeanFactory : Overriding bean definition for bean 'beanNameViewResolver' with a different definition: replacing [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration; factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration.class]] with [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter; factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter.class]]
2017-11-11 23:41:58.061 INFO 8407 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8088 (http)
2017-11-11 23:41:58.091 INFO 8407 --- [ main] o.apache.catalina.core.StandardService : Starting service Tomcat
2017-11-11 23:41:58.093 INFO 8407 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.0.30
2017-11-11 23:41:58.224 INFO 8407 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2017-11-11 23:41:58.224 INFO 8407 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 2077 ms
2017-11-11 23:41:58.590 INFO 8407 --- [ost-startStop-1] o.s.b.c.e.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/]
2017-11-11 23:41:58.595 INFO 8407 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]
2017-11-11 23:41:58.596 INFO 8407 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2017-11-11 23:41:58.596 INFO 8407 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2017-11-11 23:41:58.596 INFO 8407 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]
2017-11-11 23:41:58.947 INFO 8407 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@563b3f89: startup date [Sat Nov 11 23:41:56 CST 2017]; root of context hierarchy
2017-11-11 23:41:59.028 INFO 8407 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/]}" onto public java.lang.String springboot.HelloworldRestController.helloworld()
2017-11-11 23:41:59.032 INFO 8407 --- [ 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)
2017-11-11 23:41:59.032 INFO 8407 --- [ 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)
2017-11-11 23:41:59.056 INFO 8407 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-11-11 23:41:59.056 INFO 8407 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-11-11 23:41:59.091 INFO 8407 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-11-11 23:41:59.207 INFO 8407 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup
2017-11-11 23:41:59.291 ERROR 8407 --- [ main] o.a.coyote.http11.Http11NioProtocol : Failed to start end point associated with ProtocolHandler ["http-nio-8088"]
如果你遇到这种问题：Failed to start end point associated with ProtocolHandler ["http-nio-8088"]
这表明8088端口被占用了，可以通过实现EmbeddedServletContainerCustomizer接口修改SpringBoot内置的tomcat端口来解决端口被占用的问题：
package springboot; import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.embedded.ConfigurableEmbeddedServletContainer;
import org.springframework.boot.context.embedded.EmbeddedServletContainerCustomizer; @SpringBootApplication
public class HelloworldDemoApplication implements EmbeddedServletContainerCustomizer{
public static void main(String[] args){
SpringApplication.run(HelloworldDemoApplication.class, args);
} public void customize(ConfigurableEmbeddedServletContainer container) {
// TODO 自动生成的方法存根
container.setPort(8089);
}
}
修改端口为8089：再次运行：
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v1.3.2.RELEASE) 2017-11-11 23:47:48.204 INFO 8449 --- [ main] springboot.HelloworldDemoApplication : Starting HelloworldDemoApplication on pdeMacBook-Pro.local with PID 8449 (/Users/pg/Documents/workspace/springboot/target/classes started by pg in /Users/pg/Documents/workspace/springboot)
2017-11-11 23:47:48.209 INFO 8449 --- [ main] springboot.HelloworldDemoApplication : No active profile set, falling back to default profiles: default
2017-11-11 23:47:48.363 INFO 8449 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@48af20f4: startup date [Sat Nov 11 23:47:48 CST 2017]; root of context hierarchy
2017-11-11 23:47:49.230 INFO 8449 --- [ main] o.s.b.f.s.DefaultListableBeanFactory : Overriding bean definition for bean 'beanNameViewResolver' with a different definition: replacing [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration; factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/ErrorMvcAutoConfiguration$WhitelabelErrorViewConfiguration.class]] with [Root bean: class [null]; scope=; abstract=false; lazyInit=false; autowireMode=3; dependencyCheck=0; autowireCandidate=true; primary=false; factoryBeanName=org.springframework.boot.autoconfigure.web.WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter; factoryMethodName=beanNameViewResolver; initMethodName=null; destroyMethodName=(inferred); defined in class path resource [org/springframework/boot/autoconfigure/web/WebMvcAutoConfiguration$WebMvcAutoConfigurationAdapter.class]]
2017-11-11 23:47:50.197 INFO 8449 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8089 (http)
2017-11-11 23:47:50.223 INFO 8449 --- [ main] o.apache.catalina.core.StandardService : Starting service Tomcat
2017-11-11 23:47:50.225 INFO 8449 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.0.30
2017-11-11 23:47:50.360 INFO 8449 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2017-11-11 23:47:50.362 INFO 8449 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 2001 ms
2017-11-11 23:47:50.761 INFO 8449 --- [ost-startStop-1] o.s.b.c.e.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/]
2017-11-11 23:47:50.767 INFO 8449 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]
2017-11-11 23:47:50.767 INFO 8449 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2017-11-11 23:47:50.767 INFO 8449 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2017-11-11 23:47:50.768 INFO 8449 --- [ost-startStop-1] o.s.b.c.embedded.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]
2017-11-11 23:47:51.092 INFO 8449 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@48af20f4: startup date [Sat Nov 11 23:47:48 CST 2017]; root of context hierarchy
2017-11-11 23:47:51.161 INFO 8449 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/]}" onto public java.lang.String springboot.HelloworldRestController.helloworld()
2017-11-11 23:47:51.164 INFO 8449 --- [ 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)
2017-11-11 23:47:51.165 INFO 8449 --- [ 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)
2017-11-11 23:47:51.193 INFO 8449 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-11-11 23:47:51.194 INFO 8449 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-11-11 23:47:51.237 INFO 8449 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-11-11 23:47:51.365 INFO 8449 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup
2017-11-11 23:47:51.463 INFO 8449 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8089 (http)
2017-11-11 23:47:51.471 INFO 8449 --- [ main] springboot.HelloworldDemoApplication : Started HelloworldDemoApplication in 14.261 seconds (JVM running for 19.706)
2017-11-11 23:51:29.888 INFO 8449 --- [nio-8089-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring FrameworkServlet 'dispatcherServlet'
2017-11-11 23:51:29.890 INFO 8449 --- [nio-8089-exec-1] o.s.web.servlet.DispatcherServlet : FrameworkServlet 'dispatcherServlet': initialization started
2017-11-11 23:51:29.920 INFO 8449 --- [nio-8089-exec-1] o.s.web.servlet.DispatcherServlet : FrameworkServlet 'dispatcherServlet': initialization completed in 30 ms
打开浏览器输入：localhost:8089
基于Maven的SpringBoot简单使用就完成了。