Spring Boot自定义starters

starter：

• 这个场景需要使用到的依赖是什么？
• 如何编写自动配置

• /**
   * 以WebMvcAutoConfiguration为例
   */
  
  //指定这个类是一个配置类
  @Configuration(proxyBeanMethods = false)
  //@ConditionalOnXXX: 在指定条件成立的情况下自动配置类生效
  @ConditionalOnWebApplication(type = Type.SERVLET)
  @ConditionalOnClass({ Servlet.class, DispatcherServlet.class, WebMvcConfigurer.class })
  @ConditionalOnMissingBean(WebMvcConfigurationSupport.class)
  //指定自动配置类的顺序
  @AutoConfigureOrder(Ordered.HIGHEST_PRECEDENCE + 10)
  @AutoConfigureAfter({ DispatcherServletAutoConfiguration.class,TaskExecutionAutoConfiguration.class,ValidationAutoConfiguration.class })
  //给容器中添加组件
  @Bean
  
  //结合相关xxxProperties类来绑定相关的配置
  @ConfigurationPropertie
  //让xxxProperties生效加入到容器中
  @EnableConfigurationProperties
  
  //自动配置类要能加载
  //将需要启动就加载的自动配置类，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 

  • 启动器只用来做依赖导入

  • 专门来写一个自动配置模块

  • 启动器依赖自动配置，别人只需要引入启动器（starter）

  • mybatis-spring-boot-starter，自定义启动器名-spring-boot-starter

• 

步骤：

• 当我们的类需要使用自定义的模块时，就需要启动器模块进行依赖

• <?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>
  
      <!--启动器-->
      <dependencies>
  
          <!--引入自动配置模块-->
          <dependency>
              <groupId>com.atguigu.starter</groupId>
              <artifactId>atguigu-spring-boot-starter-autoconfigurer</artifactId>
              <version>0.0.1-SNAPSHOT</version>
          </dependency>
      </dependencies>
  
  </project>

• 自动配置模块

• <?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应用才生效
  @EnableConfigurationProperties(HelloProperties.class)
  public class HelloServiceAutoConfiguration {
  
      @Autowired
      HelloProperties helloProperties;
      @Bean
      public HelloService helloService(){
          HelloService service = new HelloService();
          service.setHelloProperties(helloProperties);
          return service;
      }
  }

• 
• spring.factories：用来引用自动配置类

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

• 根据顺序将自动配置类生成jar包
• 
• 重新生成新的项目
• 在pom文件中添加依赖

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

• 写一个测试类Controller

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

• 在application.properties中添加一些参数

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

• 运行项目
• 
• 说明我们写的自动配置类可以用！！！