springBoot核心技术概览

springBoot核心技术概览

核心特性

组件自动装备(webMVC, web Flux,JDBC等)

• 激活： @EnableAutoConfiguration
• 配置： /META-INF/spring.factories
• 实现： XXXAutoConfiguration

嵌入式Web容器

• Web Servlet 容器：Tomcat,jetty和Undertow
• Web Reactive 容器:Netty web server

生产准备特性

• 指标（Metrics）/actuator/metrics
• 健康检查（Health Check）/actuator/health
• 外部化配置（Externalized Configuration）/actuator/configprops

web应用

传统 Servlet 应用

依赖

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

Servlet 组件

• servlet
  • 实现
    • @WebServlet,使用此注解
    • URL映射 @WebServlet(urlPatterns = "/my/servlet"}
    • 注册,见下面@ServletComponentScan(basePackages = "com.imooc.diveinspringboot.web.servlet")

@WebServlet(urlPatterns = "/my/servlet")
public class MyServlet extends HttpServlet {}

• Filter
• Listener

Servlet注册

• servlet注解
  • @ServletComponentScan +
    • @WebServlet
    • @WebFilter
    • @WebListener

@SpringBootApplication
@ServletComponentScan(basePackages = "com.imooc.diveinspringboot.web.servlet")
public class DiveInSpringBootApplication {
    public static void main(String[] args) {
        new SpringApplicationBuilder(DiveInSpringBootApplication.class)
				.web(WebApplicationType.NONE)
                .run(args);
		SpringApplication.run(DiveInSpringBootApplication.class, args);
    }
}

• Spring Bean
  • @Bean +
    • Servlet
    • Filter
    • Listener
• RegistrationBean
  • ServletRegistrationBean
  • FilterRegistrationBean
  • ServletListenerRegistrationBean

异步非阻塞

• 异步 Servlet
  • javax.servlet.ServletRequest#startAsync()
  • javax.servlet.AsyncContext

@WebServlet(urlPatterns = "/my/servlet",
        asyncSupported=true)
public class MyServlet extends HttpServlet {
    protected void doGet(HttpServletRequest req, HttpServletResponse resp)
            throws ServletException, IOException {
        AsyncContext asyncContext = req.startAsync();
        asyncContext.start(()->{
            try {
                resp.getWriter().println("Hello,World");
                // 触发完成
                asyncContext.complete();
            } catch (IOException e) {
                e.printStackTrace();
            }
        });
    }
}

• 非阻塞 Servlet
  • javax.servlet.ServletInputStream#setReadListener
  • javax.servlet.ReadListener
  • javax.servlet.ServletOutputStream#setWriteListener
  • javax.servlet.WriteListener

Spring Web MVC 应用

Web MVC 视图

• ViewResolver
• View

模板引擎

• Thymeleaf
• Freemarker
• JSP

内容协商

• ContentNegotiationConfigurer
• ContentNegotiationStrategy
• ContentNegotiatingViewResolver

异常处理

• @ExceptionHandler
• HandlerExceptionResolver
  * ExceptionHandlerExceptionResolver
• BasicErrorController (Spring Boot)

Web MVC REST

资源服务

• @RequestMapping
• @GetMapping
• @ResponseBody
• @RequestBody

资源跨域

• CrossOrigin
• WebMvcConfigurer#addCorsMappings
• 传统解决方案
  • IFrame
  • JSONP

服务发现

• HATEOS

Web MVC 核心

核心架构

处理流程

核心组件

• DispatcherServlet
• HandlerMapping
• HandlerAdapter
• ViewResolver

Spring Web Flux 应用

Reactor 基础

• Java Lambda
• Mono
• Flux

Web Flux 核心

Web MVC 注解兼容

• @Controller
• @RequestMapping
• @ResponseBody
• @RequestBody

函数式声明

• RouterFunction

异步非阻塞

• Servlet 3.1 +
• Netty Reactor

使用场景

页面渲染

REST 应用

性能测试

http://blog.ippon.tech/spring-5-webflux-performance-tests

Web Server 应用

切换 Web Server

切换其他 Servlet 容器

• Tomcat -> Jetty;在pom文件中添加如下

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <exclusions>
    <!-- Exclude the Tomcat dependency -->
        <exclusion>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </exclusion>
    </exclusions>
</dependency>
<!-- Use Jetty instead -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jetty</artifactId>
</dependency>

• 替换 Servlet 容器

<!--<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
    <exclusions>
     //Exclude the Tomcat dependency 
        <exclusion>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-tomcat</artifactId>
        </exclusion>
    </exclusions>
</dependency>
// Use Jetty instead
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-jetty</artifactId>
</dependency>-->
<!--以上注释掉-->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-webflux</artifactId>
</dependency>

自定义 Servlet Web Server

• WebServerFactoryCustomizer

自定义 Reactive Web Server

• ReactiveWebServerFactoryCustomizer

数据相关

关系型数据

JDBC

依赖

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

数据源

• javax.sql.DataSource

JdbcTemplate

自动装配

• DataSourceAutoConfiguration

JPA

依赖

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

实体映射关系

• @javax.persistence.OneToOne
• @javax.persistence.OneToMany
• @javax.persistence.ManyToOne
• @javax.persistence.ManyToMany

实体操作

• javax.persistence.EntityManager

自动装配

• HibernateJpaAutoConfiguration

事务（Transaction）

依赖

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-tx</artifactId>
</dependency>

Spring 事务抽象

• PlatformTransactionManager

JDBC 事务处理

• DataSourceTransactionManager

自动装配

• TransactionAutoConfiguration