2020-08-28框架Spring5 分钟读完 (大约 706 个字) 0次访问

Spring Boot自定义starter

1、SpringBoot自定义starters

SpringBoot的强大点就是把所有的场景抽象成starter场景启动器。

尽管已经定义好了，但依然可能无法满足我们的需求。

1.1 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.class为例；

@Configuration  //指定这个类是一个配置类
@ConditionalOnXXX  //在指定条件成立的情况下自动配置类生效
@AutoConfigureAfter  //指定自动配置类的顺序

@Bean  //给容器中添加组件

@ConfigurationPropertie结合相关xxxProperties类来绑定相关的配置
@EnableConfigurationProperties //让xxxProperties生效加入到容器中

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

1.2 步骤

首先在IDEA创建两个基础Maven项目：starter和autoconfiguration工程
启动器模块

<?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.custom.starter</groupId>
  <artifactId>custom-spring-boot-starter</artifactId>
  <version>1.0-SNAPSHOT</version>

  <!--启动器-->
  <dependencies>
    <!--引入自动配置模块-->
    <dependency>
      <groupId>com.custom.starter</groupId>
      <artifactId>custom-spring-boot-starter-autoconfiguration</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.custom.starter</groupId>
  <artifactId>custom-spring-boot-starter-autoconfiguration</artifactId>
  <version>0.0.1-SNAPSHOT</version>
  <packaging>jar</packaging>

  <name>custom-spring-boot-starter-autoconfiguration</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>

编写可配置属性

@ConfigurationProperties(prefix = "custom.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;
  }
}

编写场景

public class HelloService {

  HelloProperties helloProperties;

  public HelloProperties getHelloProperties() {
    return helloProperties;
  }

  public void setHelloProperties(HelloProperties helloProperties) {
    this.helloProperties = helloProperties;
  }

  public String sayHello(String name){
    return helloProperties.getPrefix()+"-" +name + helloProperties.getSuffix();
  }
}

编写属性生效的自动配置类

@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;
  }
}

同样，想要配置类生效，就要在resources/META-INF/spring.factories编写路径

1 2	org.springframework.boot.autoconfigure.EnableAutoConfiguration=\ com.custom.starter.HelloServiceAutoConfiguration

最后将这2个项目都安装到Maven仓库中，点击IDEA右边Maven Projects，在两个项目的Lifecycle下点击install安装即可。

1.3 测试

创建一个新的项目，测试上面我们自定义的starters

在项目的pom.xml文件中引入，自定义starters

<!--引入自定义的starter-->
<dependency>
  <groupId>com.custom.starter</groupId>
  <artifactId>atguigu-spring-boot-starter</artifactId>
  <version>1.0-SNAPSHOT</version>
</dependency>

控制类

@RestController
public class HelloController {

  @Autowired
  HelloService helloService;

  @GetMapping("/hello")
  public String hello(){
    return helloService.sayHello("starter");
  }
}