十七、SpringBoot之自定义starter

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1.自定义场景启动器(starter)需要知道什么？

• ​ 这个场景需要使用到的依赖是什么？
• ​ 如何编写自动配置

@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）

2.步骤：

• 创建启动模块和自动配置模块

• 启动器模块

pom.xml

<?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

pom.xml

<?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>2.0.5.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>

    <!--引入spring-boot-starter：所有starter基本配置-->
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
    </dependencies>
</project>

Properties

@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;
    }
}

AutoConfiguration

@Configuration
@ConditionalOnWebApplication
@EnableConfigurationProperties(HelloProperties.class)
public class HelloServiceAutoConfiguration {
    @Autowired
    HelloProperties helloProperties;

    @Bean
    public HelloServices helloServices(){
        HelloServices services = new HelloServices();
        services.setHelloProperties(helloProperties);
        return services;
    }
}

HelloServices

public class HelloServices {
    HelloProperties helloProperties;
    public String sayHelloAtguigu(String name){
        return helloProperties.getPrefix()+"-"+name+"-"+helloProperties.getSuffix();
    }

    public HelloProperties getHelloProperties() {
        return helloProperties;
    }

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

META-INF/spring.factories

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.atguigu.starter.HelloServiceAutoConfiguration

• test

Controller

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

application.properties

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

pom.xml

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

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