Spring Boot自定義starters

starter：

• 這個場景需要使用到的依賴是什麼？
• 如何編寫自動配置

• /**
   * 以WebMvcAutoConfiguration爲例
   */
  
  //指定這個類是一個配置類
  @Configuration(proxyBeanMethods = false)
  //@ConditionalOnXXX: 在指定條件成立的情況下自動配置類生效
  @ConditionalOnWebApplication(type = Type.SERVLET)
  @ConditionalOnClass({ Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class })
  @ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
  //指定自動配置類的順序
  @AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
  @AutoConfigureAfter({ DispatcherServletAutoConfiguration.class,TaskExecutionAutoConfiguration.class,ValidationAutoConfiguration.class })
  //給容器中添加組件
  @Bean
  
  //結合相關xxxProperties類來綁定相關的配置
  @ConfigurationPropertie
  //讓xxxProperties生效加入到容器中
  @EnableConfigurationProperties
  
  //自動配置類要能加載
  //將需要啓動就加載的自動配置類，配置在META-INF/spring.factories
  org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
  org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration,\
  org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,\

• 模式 

  • 啓動器只用來做依賴導入

  • 專門來寫一個自動配置模塊

  • 啓動器依賴自動配置，別人只需要引入啓動器（starter）

  • mybatis-spring-boot-starter，自定義啓動器名-spring-boot-starter

步驟：

• 當我們的類需要使用自定義的模塊時，就需要啓動器模塊進行依賴

• <?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.atguigu.starter</groupId>
      <artifactId>atguigu-spring-boot-starter</artifactId>
      <version>1.0-SNAPSHOT</version>
  
      <!--啓動器-->
      <dependencies>
  
          <!--引入自動配置模塊-->
          <dependency>
              <groupId>com.atguigu.starter</groupId>
              <artifactId>atguigu-spring-boot-starter-autoconfigurer</artifactId>
              <version>0.0.1-SNAPSHOT</version>
          </dependency>
      </dependencies>
  
  </project>

• 自動配置模塊

• <?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.atguigu.starter</groupId>
     <artifactId>atguigu-spring-boot-starter-autoconfigurer</artifactId>
     <version>0.0.1-SNAPSHOT</version>
     <packaging>jar</packaging>
  
     <name>atguigu-spring-boot-starter-autoconfigurer</name>
     <description>Demo project for Spring Boot</description>
  
     <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>1.5.10.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>
     </properties>
  
     <dependencies>
        <!--引入spring-boot-starter；所有starter的基本配置-->
        <dependency>
           <groupId>org.springframework.boot</groupId>
           <artifactId>spring-boot-starter</artifactId>
        </dependency>
     </dependencies>
  
  </project>
  

• package com.atguigu.starter;
  
  import org.springframework.boot.context.properties.ConfigurationProperties;
  
  @ConfigurationProperties(prefix = "atguigu.hello")
  public class HelloProperties {
  
      private String prefix;
      private String suffix;
  
      public String getPrefix() {
          return prefix;
      }
  
      public void setPrefix(String prefix) {
          this.prefix = prefix;
      }
  
      public String getSuffix() {
          return suffix;
      }
  
      public void setSuffix(String suffix) {
          this.suffix = suffix;
      }
  }

• package com.atguigu.starter;
  
  public class HelloService {
  
      HelloProperties helloProperties;
  
      public HelloProperties getHelloProperties() {
          return helloProperties;
      }
  
      public void setHelloProperties(HelloProperties helloProperties) {
          this.helloProperties = helloProperties;
      }
  
      public String sayHellAtguigu(String name){
          return helloProperties.getPrefix()+"-" +name + helloProperties.getSuffix();
      }
  }
  

• package com.atguigu.starter;
  
  import org.springframework.beans.factory.annotation.Autowired;
  import org.springframework.boot.autoconfigure.condition.ConditionalOnWebApplication;
  import org.springframework.boot.context.properties.EnableConfigurationProperties;
  import org.springframework.context.annotation.Bean;
  import org.springframework.context.annotation.Configuration;
  
  @Configuration
  @ConditionalOnWebApplication //web應用才生效
  @EnableConfigurationProperties(HelloProperties.class)
  public class HelloServiceAutoConfiguration {
  
      @Autowired
      HelloProperties helloProperties;
      @Bean
      public HelloService helloService(){
          HelloService service = new HelloService();
          service.setHelloProperties(helloProperties);
          return service;
      }
  }

• spring.factories：用來引用自動配置類

• # Auto Configure
  org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
  com.atguigu.starter.HelloServiceAutoConfig

• 根據順序將自動配置類生成jar包
• 重新生成新的項目
• 在pom文件中添加依賴

• <!--引入自定義的Starter-->
  <dependency>
      <groupId>com.atguigu.starter</groupId>
      <artifactId>atguigu-spring-boot-starter-autoconfigurer</artifactId>
      <version>0.0.1-SNAPSHOT</version>
  </dependency>

• 寫一個測試類Controller

• @RestController
  public class HelloController {
  
      @Autowired
      HelloService helloService;
  
      @GetMapping("/hello")
      public String hello(){
          return helloService.sayHelloAtguigu("haha");
      }
  }

• 在application.properties中添加一些參數

• atguigu.hello.prefix=ATGUIGU
  atguigu.hello.suffix=HELLO WORLD

• 運行項目
• 說明我們寫的自動配置類可以用！！！