SpringBoot学习之入门篇

经过多年的发展java的开发体系也越来越全面我们经历了从spring2.5、springMVC3X到现在的springboot,虽然开发方式发生了变化，唯一不变的是我们仍然需要坚持不懈的学习劲头和激情，不断努力不断提高，因此这次特地分享下最近学习springboot的经验，这里不会每个步骤都写的那么详细，就简明扼要的写一下

一  学习springboot需要具备的基本要求

1 对spring以及springmvc有使用经验和基础的调试能力

2 有jpa或者hibernate的使用经验

3 会使用freemarker

4 熟练使用mybatis

5 熟练使用maven

6 简单使用服务器中间件如tomcat,jboss，weblogic等

如果掌握了以上技术，springboot便能快速上手一学就会，因此springboot对程序员的综合能力还是很高的

二  下面介绍springboot的基本配置和application.properties

经过一段时间的学习我觉得springboot的特色是规约配置，也就是说springboot中规则大于配置，更多的我们需要记住里面的那些规则，如下图所示

看到这里不知道大家会不会和我一样对springboot的灵活性感到无比惊讶，关于配置文件里的众多配置大家可以查查资料，这里就不全部写出来了

三  项目创建后pom文件的写法

maven的使用就不说了，直接贴给大家一个常用的，如下所示

  4.0.0

  com.debug
  usemybatis
  0.0.1-SNAPSHOT
  jar

  usemybatis
  http://maven.apache.org

 
		UTF-8
		1.8
	

	
		org.springframework.boot
		spring-boot-starter-parent
		1.4.5.RELEASE
	

	
		
		org.springframework.boot
		spring-boot-starter-web
		
	

	
		
			org.springframework.boot
			spring-boot-devtools
			true
			true
		
	
		


		
			junit
			junit
			3.8.1
			test
		
	

	
		
			
				org.springframework.boot
				spring-boot-maven-plugin
				
					
					true
				
			
		
	

如果有需要直接引入所需依赖就可以了

四 springboot的启动入口

默认情况下项目创建完毕后会生产一个叫App.java的文件，我们只需要在这个文件上加上注解以及 SpringApplication.run(App.class, args);就OK了，如下所示：

package com.debug;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

/**
 * Hello world!
 *
 */
@SpringBootApplication
public class App 
{
    public static void main( String[] args )
    {
        System.out.println( "Hello World!" );
        SpringApplication.run(App.class, args);
    }
}

运行也很简单，直接在这个文件右键选择Run as -->Java Application即可，如果没有问题启动会控制台会有如下显示

Hello World!
                                     .__              ___.                  __   
  _____ ___.__.   ___________________|__| ____    ____\_ |__   ____   _____/  |_ 
 /     <   |  |  /  ___/\____ \_  __ \  |/    \  / ___\| __ \ /  _ \ /  _ \   __\
|  Y Y  \___  |  \___ \ |  |_> >  | \/  |   |  \/ /_/  > \_\ (  <_> |  <_> )  |  
|__|_|  / ____| /____  >|   __/|__|  |__|___|  /\___  /|___  /\____/ \____/|__|  
      \/\/           \/ |__|                 \//_____/     \/                    
2017-09-24 13:08:13.260  INFO 10632 --- [           main] com.debug.App                            : Starting App on cry with PID 10632 (G:\stsspace\usespringboot01\target\classes started by chenwill2 in G:\stsspace\usespringboot01)
2017-09-24 13:08:13.281  INFO 10632 --- [           main] com.debug.App                            : The following profiles are active: prod
2017-09-24 13:08:13.558  INFO 10632 --- [           main] ationConfigEmbeddedWebApplicationContext : Refreshing org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@635eaaf1: startup date [Sun Sep 24 13:08:13 CST 2017]; root of context hierarchy
2017-09-24 13:08:27.815  INFO 10632 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat initialized with port(s): 80 (http)
2017-09-24 13:08:27.863  INFO 10632 --- [           main] o.apache.catalina.core.StandardService   : Starting service Tomcat
2017-09-24 13:08:27.864  INFO 10632 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.11
2017-09-24 13:08:28.367  INFO 10632 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2017-09-24 13:08:28.368  INFO 10632 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 14831 ms
2017-09-24 13:08:28.613  INFO 10632 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Mapping servlet: 'dispatcherServlet' to [/]
2017-09-24 13:08:28.621  INFO 10632 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2017-09-24 13:08:28.678  INFO 10632 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2017-09-24 13:08:28.678  INFO 10632 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2017-09-24 13:08:28.678  INFO 10632 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2017-09-24 13:08:29.274  INFO 10632 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.context.embedded.AnnotationConfigEmbeddedWebApplicationContext@635eaaf1: startup date [Sun Sep 24 13:08:13 CST 2017]; root of context hierarchy
2017-09-24 13:08:29.413  INFO 10632 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/hello/sayHello.do]}" onto public java.lang.String com.debug.HelloController.sayHello()
2017-09-24 13:08:29.415  INFO 10632 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/hi/sayHi.do]}" onto public java.lang.String com.debug.HiController.sayHi()
2017-09-24 13:08:29.420  INFO 10632 --- [           main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity> org.springframework.boot.autoconfigure.web.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2017-09-24 13:08:29.422  INFO 10632 --- [           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)
2017-09-24 13:08:29.468  INFO 10632 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-09-24 13:08:29.468  INFO 10632 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-09-24 13:08:29.539  INFO 10632 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2017-09-24 13:08:29.802  INFO 10632 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2017-09-24 13:08:30.553  INFO 10632 --- [           main] s.b.c.e.t.TomcatEmbeddedServletContainer : Tomcat started on port(s): 80 (http)
2017-09-24 13:08:30.558  INFO 10632 --- [           main] com.debug.App                            : Started App in 19.18 seconds (JVM running for 21.845)

五 controller的写法大致如下

package com.debug;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

	@RequestMapping("/hello/sayHello.do")
	public String sayHello() {
		return "Hello Spring Boot!";
	}
	
}

@RestController类似@Controller加@RequestMapping的用法，如果是web开发使用springmvc的那套就是@Controller加@RequestMapping会比较方便，类似webservice的数据交互使用@RestController比较方便

从浏览器输入url后运行效果如下

至此第一个springboot程序就写完了

备注：开发工具我使用的是spring tool suite, jdk是1.8的版本