本文的目的是簡單介紹Spring Boot的一些入門配置的Quick Start，幫助快速上手；

不涉及Spring Boot的概念的介紹講解，如需了解請參考Spring Boot 官方文檔；

有關(guān)Spring Boot的優(yōu)缺點和適用場景的文章已經(jīng)很多，還請自行Baidu/Google；

• 開始

Spring Boot采用約定優(yōu)于配置的方式，相比原來Spring框架,配置有了大幅的簡化，不僅配置文件寫起來簡單多了，而且pom.xml的依賴配置也進行了優(yōu)化，具體請參考Spring Boot Starter

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

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

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

只需要這樣幾行簡單的配置，就能寫基于Spring MVC的Hello World了

@RestController
class HelloWorld { 
  @RequestMapping("/")
  String home() { 
    return "Hello World!"; 
  }
}

然后寫個入口

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

啟動main方法，運行、調(diào)試都很簡單

• 加上日志

開始一個項目的時候，日志是比不可少的，先把日志加上，避免了System.out.println的泛濫。
Spring Boot的默認配置文件是 application.properties， 不使用默認配置的選項全都在這里定義
Spring Boot 默認使用logback，無需任何配置就可以使用了，并提供了

logging.config= # Location of the logging configuration file. For instance classpath:logback.xml for Logback
logging.exception-conversion-word=%wEx # Conversion word used when logging
exceptions.logging.file= # Log file name. For instance myapp.log
logging.level.*= # Log levels severity mapping. For instancelogging.level.org.springframework=DEBUG
logging.path= # Location of the log file. For instance /var/log
logging.pattern.console= # Appender pattern for output to the console. Only supported with the default logback setup.logging.pattern.file= # Appender pattern for output to the file. Only supported with the default logback
setup.logging.pattern.level= # Appender pattern for log level (default %5p). Only supported with the default logback
setup.logging.register-shutdown-hook=false # Register a shutdown hook for the logging system when it is initialized.

如果有更具體配置，如async appender，remote appender等還需使用原有的XML配置文件，如果使用默認配置文件名logback-spring.xml，則可以直接生效，無需添加一行配置
如果想使用log4j2或其他的請參考howto logging

• 寫個測試

注：standalone的Spring Boot程序只允許在jar中存在一個main方法

所以原來習(xí)慣寫個main方法來測試代碼的同學(xué)，是時候了解怎樣寫測試了，請移步到Junit深造
首先，添加依賴

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

測試的starter已經(jīng)包含了測試工具：Junit Hamcrest Mockito等，可以直接上手寫case了

@RunWith(SpringRunner.class)
@SpringBootTest
@AutoConfigureMockMvc
@AutoConfigureTestDatabase
public class UserVehicleControllerApplicationTests {   
  @Autowired   
  private MockMvc mvc;   
  @Autowired   
  private ApplicationContext applicationContext;   
  @MockBean   
  private UserVehicleService userVehicleService;   
  @Test   
  public void getVehicleWhenRequestingTextShouldReturnMakeAndModel() throws Exception {
    given(this.userVehicleService.getVehicleDetails("sboot")).willReturn(new
    VehicleDetails("Honda", "Civic"));
     this.mvc.perform(get("/sboot/vehicle").accept(MediaType.TEXT_PLAIN))
      .andExpect(status().isOk()).andExpect(content().string("Honda Civic"));   
   } 
  @Test
  public void welcomeCommandLineRunnerShouldBeAvailable() throws Exception {
     assertThat(this.applicationContext.getBean(WelcomeCommandLineRunner.class).isNotNull();
  }
}

測試?yán)诱埧?spring-boot-sample-test

• 數(shù)據(jù)庫連接池

數(shù)據(jù)庫連接池也是大多數(shù)項目的標(biāo)配，在Spring Boot中引入也十分簡單
以mysql為例，pom中添加依賴：

<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>5.1.26</version>
</dependency>
<dependency>
<groupId>com.zaxxer</groupId>
<artifactId>HikariCP</artifactId>
<version>2.4.7</version>
<scope>compile</scope>
</dependency>

請使用tomcat 和 C3p0 連接池的同學(xué)移駕 HikariCP 補課

application.properties 中添加：

datasource.url=jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8
datasource.username=user
datasource.password=password
spring.datasource.url=${datasource.url}
spring.datasource.username=${datasource.username}
spring.datasource.password=${datasource.password}
spring.datasource.type=com.zaxxer.hikari.HikariDataSource
spring.datasource.hikari.maximum-pool-size=20
spring.datasource.hikari.max-lifetime=30000
spring.datasource.hikari.idle-timeout=30000
spring.datasource.hikari.data-source-properties.prepStmtCacheSize=250
spring.datasource.hikari.data-source-properties.prepStmtCacheSqlLimit=2048
spring.datasource.hikari.data-source-properties.cachePrepStmts=true
spring.datasource.hikari.data-source-properties.useServerPrepStmts=true

這樣Spring Boot會自動識別這些配置并加載jdbcTemplate和dataSource的bean

• Mybatis

Hibernate,JPA,JOOQ的同學(xué)請參考 [Working With Database](29. Working with SQL databases)
Mybatis 開發(fā)了自己的starter依賴

<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>1.1.1</version>
</dependency>

然后就可以像往常一樣編寫Dao了

@Mapper
public interface DemoDao {    
  @Select("select * from test")    
  public List<TestDomain> get();    
  @Insert("insert into test (name,age) values (#{name},#{age})")    
  void insert(@Param("name") String name, @Param("age") String age);
}

當(dāng)然如果遇到要寫一些復(fù)雜的SQL或者需要include SQL的話，使用xml文件來寫SQL會更方便，只需給定xml文件的未知即可 mybatis-mapper-locations=classpath*:**/mapper/*
詳細Mybatis的請參考 mybatis-spring-boot-autoconfigure

• 數(shù)據(jù)庫管理 Flyway

Flyway的具體使用方法請移步官網(wǎng)參考
添加pom依賴

<dependency>
<groupId>org.flywaydb</groupId>
<artifactId>flyway-core</artifactId>
</dependency>

配置中加入：

flyway.enabled=true
flyway.schemas=test

腳本默認位置：classpath:db\migration
搞定，程序啟動自動執(zhí)行數(shù)據(jù)庫腳本

• Redis

廢話不說了
pom

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

properties

spring.redis.database=0
spring.redis.host=127.0.0.1
spring.redis.password=
spring.redis.pool.max-active=-1
spring.redis.pool.max-idle=100
spring.redis.port=6379
spring.redis.timeout=0

code

@AutowiredRedisTemplate redisTemplate;

• 異常處理之ExceptionHandler

當(dāng)Controller拋出異常后需要進行處理，以返回友好信息給clients

  @ControllerAdvice(basePackageClasses = CoreApplication.class)
  public class DemoControllerAdvice {
  @ExceptionHandler(DemoException.class)
  @ResponseBody
  ResponseEntity<?> handleControllerException(HttpServletRequest request, Throwable ex) {
  HttpStatus status = getStatus(request);
  return new ResponseEntity<DemoError>(new DemoError(status.value(), ex.getMessage()), status);
  }
  @ExceptionHandler(Exception.class)
  @ResponseBody
  ResponseEntity<?> handleException(HttpServletRequest request, Throwable ex) {
  HttpStatus status = getStatus(request);
  return new ResponseEntity<DemoError>(new DemoError(status.value(), ex.getMessage()), status);
  }
  private HttpStatus getStatus(HttpServletRequest request) {
  Integer statusCode = (Integer) request.getAttribute("javax.servlet.error.status_code");
  if (statusCode == null) {
    return HttpStatus.INTERNAL_SERVER_ERROR;
  }
  return HttpStatus.valueOf(statusCode);
  }
  }

• 異常處理之ErrorController

容器處理失敗的請求會自動轉(zhuǎn)到 /error 來處理，實現(xiàn)ErrorController接口來自定義該異常的處理機制
@RestController
public class DemoErrorController implements ErrorController {
@Autowired
ErrorAttributes errorAttributes;

    @RequestMapping(value = "/error")
    public ResponseEntity<Map<String, Object>> error(HttpServletRequest request) {
        Map body = this.getErrorAttributes(request, this.isIncludeStackTrace(request, MediaType.ALL));
        HttpStatus status = this.getStatus(request);
        return new ResponseEntity(body, status);
    }
    protected boolean isIncludeStackTrace(HttpServletRequest request, MediaType produces) {
       return false;
    }
    protected Map<String, Object> getErrorAttributes(HttpServletRequest request, boolean includeStackTrace) {
        ServletRequestAttributes requestAttributes = new ServletRequestAttributes(request);
        return this.errorAttributes.getErrorAttributes(requestAttributes, includeStackTrace);
    }
    protected HttpStatus getStatus(HttpServletRequest request) {
        Integer statusCode = (Integer)request.getAttribute("javax.servlet.error.status_code");
        if(statusCode == null) {
            return HttpStatus.INTERNAL_SERVER_ERROR;
        } else {
            try {
                return HttpStatus.valueOf(statusCode.intValue());
            } catch (Exception var4) {
                return HttpStatus.INTERNAL_SERVER_ERROR;
            }
        }
    }
    @Override
    public String getErrorPath() {
        return "/error";
    }
  }

• 自定義攔截器

與Spring MVC一樣，定義一個攔截器

public class DemoInterceptor  implements HandlerInterceptor {
    private final Logger logger = LoggerFactory.getLogger(this.getClass());
    @Override
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        logger.info("pre handle");
        return true;
    }

    @Override
    public void postHandle(HttpServletRequest httpServletRequest, HttpServletResponse httpServletResponse, Object o, ModelAndView modelAndView) throws Exception {
        logger.info("post handle");
    }

    @Override
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response,Object handler, Exception ex) throws Exception {
        logger.info("after completion");
    }
  }

然后在WebMvcConfigurerAdapter的子類中把定義好的攔截器添加到容其中

    @Configuration
    public class DemoConfiguration  extends WebMvcConfigurerAdapter {

        private final Logger logger = LoggerFactory.getLogger(this.getClass());
        public void addInterceptors(InterceptorRegistry registry) {
            registry.addInterceptor(new DemoInterceptor()).addPathPatterns("/**");
        }
    }

其他的與Spring MVC一樣

• 多環(huán)境處理

開發(fā)過程中，總會遇到本機環(huán)境、CI環(huán)境，測試環(huán)境、UAT環(huán)境、生產(chǎn)環(huán)境等等不同環(huán)境間的切換，往往因為環(huán)境的不同需要寫不同的配置文件，又要有不同的腳本去替換這些配置文件，然后又要有一套版本管理系統(tǒng)把配置文件、腳本管理起來。
在Spring Boot中，這些問題統(tǒng)統(tǒng)可以自動處理。我們可以通過定義一個啟動參數(shù)來指定當(dāng)前啟動的環(huán)境是那個，那么該環(huán)境的配置文件就會被加載執(zhí)行。
啟動參數(shù)：java -jar -Dspring.profiles.active=production app.jar
Spring Boot 首先會加載默認的配置文件application.properties，然后會根據(jù)指定的參數(shù)加載特定環(huán)境的配置文件application-*.properties，例如：application-production.properties
而我們要做的只是將配置文件放到指定的config路徑下即可。

目錄結(jié)構(gòu)

• 定時器

增加定時器也很容易，使用@EnableScheduling注解

    @Configuration
    @EnableScheduling
    public class DemoJob {
        private final Logger logger = LoggerFactory.getLogger(this.getClass());
        @Scheduled(cron="${Demo.Cron.Expression}")
        public void fire() {
            logger.info("scheduler fired");
        }
    }

定義Cron Expression
Demo.Cron.Expression=0 0/1 * * * ?

如果需要在不同的環(huán)境有不同的執(zhí)行策略，可以通過在不同環(huán)境的配置文件中定義不同Expression來做
如果只需要在某些環(huán)境中執(zhí)行，還可以指定bean的加載環(huán)境：

@EnableScheduling
@Profile({ "UAT", "Production" })
public class DemoJob{...}

這樣，只有在指定了環(huán)境是UAT或Production時，Spring Boot才會初始化這個bean

• 加個開機提示

No Bug

在配置文件中加入
# BANNER banner.charset=UTF-8 banner.location=classpath:banner.txt

• Spring Boot Actuator

Spring Boot提供了一些監(jiān)控管理應(yīng)用程序的功能，例如JVM運行時資源監(jiān)控、應(yīng)用負載等
請自行查閱文檔吧。
注：這些監(jiān)控管理功能一定要配合Security使用，要有權(quán)限控制，建議生產(chǎn)環(huán)境時將這些權(quán)限控制在本機或內(nèi)網(wǎng)。

• 最后

到這里，一個簡單的Spring Boot Web 應(yīng)用應(yīng)該可以順利跑起來了，請在使用前認真閱讀官方文檔。

• Demo 下載

整理好會提供。