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。通過這種方式，Boot致力於在蓬勃發展的快速應用開發領域（rapid application development）成為領導者。

Spring boot的特點

1. 創建獨立的Spring應用程序

2. 嵌入的Tomcat，無需部署WAR文件

3. 簡化Maven配置

4. 自動配置Spring

5. 提供生產就緒型功能，如指標，健康檢查和外部配置

6. 絕對沒有代碼生成和對XML沒有要求配置

Spring boot的優點

spring boot 可以支持你快速的開發出 restful 風格的微服務架構

自動化確實方便，做微服務再合適不過了，單一jar包部署和管理都非常方便。只要系統架構設計合理，大型項目也能用，加上nginx負載均衡，輕鬆實現橫向擴展

spring boot 要解決的問題, 精簡配置是一方面, 另外一方面是如何方便的讓spring生態圈和其他工具鏈整合(比如redis, email, elasticsearch)

Spring boot的使用

1、maven配置文件

 

<project>	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>org.springboot.sample/<groupid>
	<artifactid>spring-boot-sample/<artifactid>
	<version>0.0.1-SNAPSHOT/<version>
	<packaging>war/<packaging>
	<name>spring-boot-sample/<name>
	<description>Spring Boot Sample Web Application/<description>
	<parent>
		<groupid>org.springframework.boot/<groupid>
		<artifactid>spring-boot-starter-parent/<artifactid>
		<version>1.3.2.RELEASE/<version>
		<relativepath> 
	/<parent>
	<properties>
		<project.build.sourceencoding>UTF-8/<project.build.sourceencoding>
		<java.version>1.8/<java.version>
	/<properties>
	<dependencies>
		<dependency>
			<groupid>org.springframework.boot/<groupid>
			<artifactid>spring-boot-starter-web/<artifactid>
		/<dependency>
		
		<dependency>
			<groupid>mysql/<groupid>
			<artifactid>mysql-connector-java/<artifactid>
		/<dependency>
		
		<dependency>
			<groupid>org.springframework.boot/<groupid>
			<artifactid>spring-boot-starter-jdbc/<artifactid>
		/<dependency>
		<dependency>
			<groupid>org.springframework.boot/<groupid>
			<artifactid>spring-boot-configuration-processor/<artifactid>
			<optional>true/<optional>
		/<dependency>
	/<dependencies>
	<build>
		<plugins>
			<plugin>
				<groupid>org.springframework.boot/<groupid>
				<artifactid>spring-boot-maven-plugin/<artifactid>
			/<plugin>
		/<plugins> 

	/<build>
/<project>

2、application類

@SpringBootApplication
@ServletComponentScan
public class SpringBootApplication extends SpringBootServletInitializer {
 
	private static final Logger logger = LoggerFactory.getLogger(SpringBootSampleApplication.class);
 public static void main(String[] args) {
		SpringApplication.run(SpringBootSampleApplication.class, args);
	}
}

3、配置類

@Repository
@Component
@Configuration
public class MyWebAppConfigurer extends WebMvcConfigurerAdapter implements EnvironmentAware{
	private static final Logger logger = LoggerFactory.getLogger(MyWebAppConfigurer.class);
	private RelaxedPropertyResolver propertyResolver;
	@Override
	public void addInterceptors(InterceptorRegistry registry) {
		// 多個攔截器組成一個攔截器鏈
		// addPathPatterns 用於添加攔截規則
		// excludePathPatterns 用戶排除攔截
		registry.addInterceptor(new MyInterceptor1()).addPathPatterns("/**");
		registry.addInterceptor(new MyInterceptor2()).addPathPatterns("/**");
		super.addInterceptors(registry);
	}
	@Override
	public void addResourceHandlers(ResourceHandlerRegistry registry) {
		registry.addResourceHandler("/res/**").addResourceLocations("classpath:/res/");
		// 可以直接使用addResourceLocations 指定磁盤絕對路徑，同樣可以配置多個位置，注意路徑寫法需要加上file:
		registry.addResourceHandler("/imgs/**").addResourceLocations("file:D:/imgs/");
		super.addResourceHandlers(registry); 

	}
}

4、添加filter

@WebFilter(filterName="myFilter",urlPatterns="/*")
public class MyFilter implements Filter {
 @Override
 public void destroy() {
 System.out.println("過濾器銷燬");
 }
 @Override
 public void doFilter(ServletRequest request, ServletResponse response,
 FilterChain chain) throws IOException, ServletException {
 System.out.println("執行過濾操作");	
 chain.doFilter(request, response);
 }
 @Override
 public void init(FilterConfig config) throws ServletException {
 System.out.println("過濾器初始化");
 }
}

5、controller

@RestController
@RequestMapping("/hello")
public class HelloController {
	@RequestMapping("/info")
	public Map<string> getInfo(@RequestParam String name) {
		Map<string> map = new HashMap<>();
		return map;
	}	
}
/<string>/<string>

6、service

@Service
public class HelloWorldService { 

	public String getHelloMessage() {
		return "Hello world";
	}
}

7、全局異常處理

@ControllerAdvice
 public class GlobalExceptionHandler {
 @ExceptionHandler(RuntimeException.class)
 @ResponseBody //在返回自定義相應類的情況下必須有，這是@ControllerAdvice註解的規定
 public MyExceptionResponse exceptionHandler(RuntimeException e, HttpServletResponse response) {
 
 return resp;
 }
 }

說明：

@ControllerAdvice是controller的一個輔助類，最常用的就是作為全局異常處理的切面類

@ControllerAdvice可以指定掃描範圍

@ControllerAdvice約定了幾種可行的返回值，如果是直接返回model類的話，需要使用@ResponseBody進行json轉換

1、返回String，表示跳到某個view

2、返回modelAndView

3、返回model + @ResponseBody

8、添加被其他配置使用的bean

@Bean
public PageHelper pageHelper(DataSource dataSource) {
	PageHelper pageHelper = new PageHelper();
	return pageHelper;
}

9、添加數據加載類

@Component
public class MyStartupRun implements CommandLineRunner {
 @Override
 public void run(String... args) throws Exception {
 System.out.println(">>>>>>>>>>>>>>>服務啟動執行");
 }
}

該組件在項目啟動時會立即執行