springboot

      微服务，现在是一个越来越热的东西，软件架构发展到现在，越来越向轻量级方向演变，微服务的架构，慢慢被很多的中小企业认可。

 

     springboot这个项目，用来构建基于java的微服务应用，它并没有发明什么新的东西，而是让现有的开发配置更好用，更简洁。以前开发spring的项目，至少需要一个applicationContext.xml文件来做配置，但是使用springboot可以做到零配置，减少了很多的配置文件。用springboot的内嵌tomcat可以轻松发布一个web接口服务。

   

   我们来看一个简单的例子，新建一个maven工程，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>com.hua.spring.boot</groupId>
	<artifactId>springboot</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>springboot</name>
	<url>http://maven.apache.org</url>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
	</properties>
	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.4.3.RELEASE</version>
	</parent>
	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>3.8.1</version>
			<scope>test</scope>
		</dependency>
	</dependencies>
</project>

   

/**
 * 
 */
package com.hua.spring.boot.springboot;

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

@Controller
@EnableAutoConfiguration
public class SampleController {

    @RequestMapping("/")
    @ResponseBody
    String home() {
        return "Hello World!";
    }

    @RequestMapping("/w")
    @ResponseBody
    String springBoot() {
        return "welcome to spring boot";
    }

    
    public static void main(String[] args) throws Exception {
        SpringApplication.run(SampleController.class, args);
    }
}

 

 启动main程序

  

写道

. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v1.4.3.RELEASE)

2016-12-29 09:31:46.383 INFO 7988 --- [ main] c.h.s.boot.springboot.SampleController : Starting SampleController on dell2-PC with PID 7988 (D:\work-space\springboot\target\classes started by dell2 in D:\work-space\springboot)
2016-12-29 09:31:46.386 INFO 7988 --- [ main] c.h.s.boot.springboot.SampleController : No active profile set, falling back to default profiles: default
2016-12-29 09:31:46.446 INFO 7988 --- [ main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@6e4784bc: startup date [Thu Dec 29 09:31:46 CST 2016]; root of context hierarchy
2016-12-29 09:31:49.773 INFO 7988 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 8080 (http)
2016-12-29 09:31:49.799 INFO 7988 --- [ main] o.apache.catalina.core.StandardService : Starting service Tomcat
2016-12-29 09:31:49.801 INFO 7988 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.6
2016-12-29 09:31:50.175 INFO 7988 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2016-12-29 09:31:50.176 INFO 7988 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 3736 ms
2016-12-29 09:31:50.418 INFO 7988 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/]
2016-12-29 09:31:50.423 INFO 7988 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]
2016-12-29 09:31:50.424 INFO 7988 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2016-12-29 09:31:50.424 INFO 7988 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2016-12-29 09:31:50.424 INFO 7988 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]
2016-12-29 09:31:50.891 INFO 7988 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@6e4784bc: startup date [Thu Dec 29 09:31:46 CST 2016]; root of context hierarchy
2016-12-29 09:31:51.012 INFO 7988 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/]}" onto java.lang.String com.hua.spring.boot.springboot.SampleController.home()
2016-12-29 09:31:51.014 INFO 7988 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/w]}" onto java.lang.String com.hua.spring.boot.springboot.SampleController.springBoot()
2016-12-29 09:31:51.025 INFO 7988 --- [ 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)
2016-12-29 09:31:51.025 INFO 7988 --- [ 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)
2016-12-29 09:31:51.073 INFO 7988 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2016-12-29 09:31:51.074 INFO 7988 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2016-12-29 09:31:51.154 INFO 7988 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2016-12-29 09:31:51.407 INFO 7988 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup
2016-12-29 09:31:51.513 INFO 7988 --- [ main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 8080 (http)
2016-12-29 09:31:51.524 INFO 7988 --- [ main] c.h.s.boot.springboot.SampleController : Started SampleController in 5.802 seconds (JVM running for 6.349)
2016-12-29 09:32:13.640 INFO 7988 --- [nio-8080-exec-1] o.apache.tomcat.util.http.parser.Cookie : A cookie header was received [1476092382,1478080035; HISTORY="\.\.\.\.\.\.com.mor.server.dubbo.service.DemoServer..../dubboadmin/governance/services/com.mor.server.dubbo.service.DemoServer/providers\.\.\.\.\.\.com.mor.server.dubbo.service.DemoServer..../dubboadmin/governance/applications/hello-world-app/services/com.mor.server.dubbo.service.DemoServer/providers"] that contained an invalid cookie. That cookie will be ignored.Note: further occurrences of this error will be logged at DEBUG level.
2016-12-29 09:32:13.649 INFO 7988 --- [nio-8080-exec-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring FrameworkServlet 'dispatcherServlet'
2016-12-29 09:32:13.649 INFO 7988 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : FrameworkServlet 'dispatcherServlet': initialization started
2016-12-29 09:32:13.685 INFO 7988 --- [nio-8080-exec-1] o.s.web.servlet.DispatcherServlet : FrameworkServlet 'dispatcherServlet': initialization completed in 36 ms

 

 启动成功后，通过浏览器访问http://localhost:8080/w ，会出现welcome to spring boot的字符，是不是很简单？通过这一点，我们 可以开发resultful的接口，返回json类型。

 

  开发一个服务是简单了，轻量极了，任何事物都有两面性，我们在传统的nginx/tomcat模式下面，各种调优参数都可以配置，但是在这里就没那么好操作了，有一部分参数可以通过java代码来设置，但是需要开发人员知道他的API。

 

     一个对外的服务，一般都是做集群的，为了防止单点故障，那么我们通常可以把springboot的单个服务做成docker镜像，通过启动多个docker镜像的形式来实现服务的集群，当然，docker镜像的部署可以通过jenkins来动态管理。。