一、引言：

什麼是spring boot?

    Spring Boot是由Pivotal團隊提供的全新框架，其設計目的是用來簡化新Spring應用的初始搭建以及開發過程。該框架使用了特定的方式來進行配置，從而使開發人員不再需要定義樣板化的配置。用我的話來理解，就是spring boot其實不是什麼新的框架，它預設配置了很多框架的使用方式，就像maven整合了所有的jar包，spring boot整合了所有的框架（不知道這樣比喻是否合適）。

• 1）配置web.xml，載入spring和spring mvc
• 2）配置資料庫連線、配置spring事務
• 3）配置載入配置檔案的讀取，開啟註解
• 4）配置日誌檔案
• ...

...

但是如果使用spring boot呢？

使用sping boot是不是很爽，不信，接下來往下看！

二、基礎環境準備

(以Spring Boot 2.1.0.BUILD-SNAPSHOT版本搭建)

1、JDK環境安裝

       Spring Boot 2.1.0.BUILD-SNAPSHOT要求java8以上版本。在開始之前需要檢查開發環境jdk版本是否符合要求，使用以下命令檢查當前jdk版本：

C:\Users\Administrator>java -version
java version "1.8.0_121"
Java(TM) SE Runtime Environment (build 1.8.0_121-b13)
Java HotSpot(TM) 64-Bit Server VM (build 25.121-b13, mixed mode)

2、Maven安裝

Spring Boot與Apache Maven 3.2或更高版本相容。如果您尚未安裝Maven，則可以按照maven.apache.org上的說明進行操作。

(對於為何要安裝Maven，請自行查閱Maven相關資料)

三、建立SpringBoot專案

開發工具：Eclipse Jee Oxygen(v4.7.0)

1、建立Maven 工程。

2、建立pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<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.xcbeyond</groupId>
	<artifactId>springboot</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>springboot</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.0.RELEASE</version>
		<relativePath/> <!-- lookup parent from repository -->
	</parent>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
		<java.version>1.8</java.version>
		<spring-cloud.version>Finchley.M9</spring-cloud.version>
	</properties>

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

	</dependencies>

	<dependencyManagement>
		<dependencies>
			<dependency>
				<groupId>org.springframework.cloud</groupId>
				<artifactId>spring-cloud-dependencies</artifactId>
				<version>${spring-cloud.version}</version>
				<type>pom</type>
				<scope>import</scope>
			</dependency>
		</dependencies>
	</dependencyManagement>

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

	<repositories>
		<repository>
			<id>spring-milestones</id>
			<name>Spring Milestones</name>
			<url>https://repo.spring.io/milestone</url>
			<snapshots>
				<enabled>false</enabled>
			</snapshots>
		</repository>
	</repositories>

</project>

注：可以利用eclipse開啟pom.xml圖形介面方式新增依賴包。

3、編寫程式碼。

(1)、SpringBoot啟動類

新建SpringbootApplication.java檔案，如下：

package com.xcbeyond.springboot;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
/**
 * SpringBoot啟動類
 * @author xcbeyond
 * 2018年7月2日下午5:41:45
 */
@SpringBootApplication
public class SpringbootApplication {

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

注：註解@SpringBootApplication，稍後會有章節詳細說明。

（2）Controller

新建ControllerDemo.java，如下：

package com.xcbeyond.springboot.controller;

import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
/**
 * Controller demo
 * @author xcbeyond
 * 2018年7月5日下午11:22:49
 */

@RestController
public class ControllerDemo {

	@RequestMapping("/print")
	public String print() {
		return "hello SpringBoot!";
	}
}

說明：

@RestController的意思就是controller裡面的方法都以json格式輸出，不用再寫什麼配置！

四、執行SpringBoot工程

（1）啟動。

 直接執行上述的SpringbootApplication類即可，啟動後可以看到類似於如下日誌輸出：

  .   ____          _            __ _ _
 /\\ / ___'_ __ _ _(_)_ __  __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
 \\/  ___)| |_)| | | | | || (_| |  ) ) ) )
  '  |____| .__|_| |_|_| |_\__, | / / / /
 =========|_|==============|___/=/_/_/_/
 :: Spring Boot ::        (v2.0.0.RELEASE)

2018-07-05 23:02:49.681  INFO 8932 --- [           main] c.x.springboot.SpringbootApplication     : Starting SpringbootApplication on xcbeyond with PID 8932 (E:\micro-service\micro-service\springboot\target\classes started by Administrator in E:\micro-service\micro-service\springboot)
2018-07-05 23:02:49.687  INFO 8932 --- [           main] c.x.springboot.SpringbootApplication     : No active profile set, falling back to default profiles: default
2018-07-05 23:02:49.767  INFO 8932 --- [           main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.ser[email protected]4c40b76e: startup date [Thu Jul 05 23:02:49 CST 2018]; root of context hierarchy
2018-07-05 23:02:51.628  INFO 8932 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)
2018-07-05 23:02:51.655  INFO 8932 --- [           main] o.apache.catalina.core.StandardService   : Starting service [Tomcat]
2018-07-05 23:02:51.655  INFO 8932 --- [           main] org.apache.catalina.core.StandardEngine  : Starting Servlet Engine: Apache Tomcat/8.5.28
2018-07-05 23:02:51.679  INFO 8932 --- [ost-startStop-1] o.a.catalina.core.AprLifecycleListener   : The APR based Apache Tomcat Native library which allows optimal performance in production environments was not found on the java.library.path: [C:\Program Files\Java\jre1.8.0_171\bin;C:\Windows\Sun\Java\bin;C:\Windows\system32;C:\Windows;C:/Program Files/Java/jre1.8.0_171/bin/server;C:/Program Files/Java/jre1.8.0_171/bin;C:/Program Files/Java/jre1.8.0_171/lib/amd64;C:\Program Files (x86)\Common Files\Oracle\Java\javapath;C:\Windows\system32;C:\Windows;C:\Windows\System32\Wbem;C:\Windows\System32\WindowsPowerShell\v1.0\;C:\Program Files (x86)\Java\jdk1.7.0_79\bin;C:\Program Files\Git\cmd;C:\Program Files\TortoiseGit\bin;C:\Users\Administrator\AppData\Local\Microsoft\WindowsApps;;C:\Users\Administrator\Desktop\eclipse-jee-oxygen-R-win32-x86_64\eclipse;;.]
2018-07-05 23:02:51.895  INFO 8932 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/]       : Initializing Spring embedded WebApplicationContext
2018-07-05 23:02:51.895  INFO 8932 --- [ost-startStop-1] o.s.web.context.ContextLoader            : Root WebApplicationContext: initialization completed in 2134 ms
2018-07-05 23:02:52.084  INFO 8932 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean  : Servlet dispatcherServlet mapped to [/]
2018-07-05 23:02:52.091  INFO 8932 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-07-05 23:02:52.092  INFO 8932 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-07-05 23:02:52.093  INFO 8932 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-07-05 23:02:52.093  INFO 8932 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean   : Mapping filter: 'requestContextFilter' to: [/*]
2018-07-05 23:02:52.534  INFO 8932 --- [           main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.ser[email protected]4c40b76e: startup date [Thu Jul 05 23:02:49 CST 2018]; root of context hierarchy
2018-07-05 23:02:52.634  INFO 8932 --- [           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.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2018-07-05 23:02:52.637  INFO 8932 --- [           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.servlet.error.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2018-07-05 23:02:52.685  INFO 8932 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-07-05 23:02:52.685  INFO 8932 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-07-05 23:02:52.732  INFO 8932 --- [           main] o.s.w.s.handler.SimpleUrlHandlerMapping  : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-07-05 23:02:52.958  INFO 8932 --- [           main] o.s.j.e.a.AnnotationMBeanExporter        : Registering beans for JMX exposure on startup
2018-07-05 23:02:53.111  INFO 8932 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat started on port(s): 8080 (http) with context path ''
2018-07-05 23:02:53.120  INFO 8932 --- [           main] c.x.springboot.SpringbootApplication     : Started SpringbootApplication in 3.981 seconds (JVM running for 5.608)

（2）測試。

在瀏覽器中輸入http://localhost:8080/print，則會如下正常顯示，就說明已經OK啦，帥不帥！