SpringBoot主要有以下特點：

1.內建Tomcat，Jetty等伺服器
2.不需要太多依賴，提供’starter’來簡化你的maven配置
3.將盡可能的自動注入配置
4.不需要xml配置，不會生成多與程式碼

1.建立專案

我們以Eclipse為例，新建一個mavenweb專案，新增依賴：

<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/maven-v4_0_0.xsd"
 
>
  <modelVersion>4.0.0</modelVersion>
  <groupId>com.springBoot</groupId>
  <artifactId>springBootDemo</artifactId>
  <packaging>war</packaging>
  <version>0.0.1-SNAPSHOT</version>
  <name>springBootDemo Maven Webapp</name>
  <url>
 
http://maven.apache.org</url>

  <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.RELEASE</version>
   </parent>

  <dependencies>
    <dependency>
      <groupId
 
>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.12</version>
      <scope>test</scope>
    </dependency>

     <!-- 新增servlet支援 -->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>javax.servlet-api</artifactId>
        <version>3.1.0</version>
        <scope>provided</scope>
    </dependency>

    <!-- https://mvnrepository.com/artifact/javax.servlet.jsp/javax.servlet.jsp-api -->
    <dependency>
        <groupId>javax.servlet.jsp</groupId>
        <artifactId>javax.servlet.jsp-api</artifactId>
        <version>2.3.1</version>
        <scope>provided</scope>
    </dependency>

    <!-- 新增jtl支援 -->
    <dependency>
        <groupId>javax.servlet</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
    </dependency>


    <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-web</artifactId>
     </dependency>
     <dependency>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-test</artifactId>
         <scope>test</scope>
     </dependency>
     <dependency>
         <groupId>com.jayway.jsonpath</groupId>
         <artifactId>json-path</artifactId>
         <scope>test</scope>
     </dependency>
  </dependencies>

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

    <repositories>
        <repository>
            <id>spring-releases</id>
            <url>https://repo.spring.io/libs-release</url>
        </repository>
    </repositories>
    <pluginRepositories>
        <pluginRepository>
            <id>spring-releases</id>
            <url>https://repo.spring.io/libs-release</url>
        </pluginRepository>
    </pluginRepositories>
</project>

spring-boot-maven-plugin裡提供大量方便的依賴

2.建立一個簡單的JavaBean接受資料

public class HelloWorldBean {

    private final long id;
    private final String content;

    public HelloWorldBean(long id, String content) {
        this.id = id;
        this.content = content;
    }

    public long getId() {
        return id;
    }

    public String getContent() {
        return content;
    }
}

3.建立控制層

import java.util.concurrent.atomic.AtomicLong;

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

@RestController
public class BeanController {

    private static final String template = "Hello, %s!";
    private final AtomicLong counter = new AtomicLong();

    @RequestMapping("/helloWorld")
    public HelloWorldBean greeting(@RequestParam(value="name", defaultValue="World") String name) {
        return new HelloWorldBean (counter.incrementAndGet(),
                            String.format(template, name));
    }
}

4.啟動SpringBoot服務

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

@SpringBootApplication
public class Application {

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

所有程式碼編寫完成後以java應用程式的方式執行Application類，@SpringBootApplication 包括許多註解，使用@SpringBootApplication 可以更方便。在Application的main（） 方法中呼叫SpringApplication.run() 方法啟動應用程式，會看到以下介面。

然後在瀏覽器輸入http://localhost:8080/helloWorld
你會看到以下內容：

{“id”:2,”content”:”Hello, World!”}

{“id”:3,”content”:”Hello, springBoot!”}

springBoot返回的是一個json格式的字串，springBoot使用jackson庫自動將helloWord例項轉化成Json。

ok！SpringBoot版的HelloWorld已經實現了！