SpringBoot学习-part44自定义场景启动器Starter

stater:

这个场景需要用到的依赖是什么？
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
@AutoConfiureAfter//指定自动配置类的相对顺序

@Bean//给容器中添加组件
@EnableConfigurationProperties//结合相关xxProperties类来绑定相关的配置

创建Empty工程

创建新模块

第一个为Maven模块
第二个为SpringInitializer模块

将autoconfig的模块坐标放入到starter的依赖文件中

starter的pom.xml文件

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

    <!--启动器依赖-->
    <dependencies>
        <!--引入自动配置模块-->
        <dependency>
            <groupId>com.ezerbelcn.starter</groupId>
            <artifactId>ezerbelcn-spring-boot-starter-autoconfigurer</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
    </dependencies>

</project>

删除无用的文件

Configurer的pom.xml只保留spring-boot-starter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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.ezerbelcn.starter</groupId>
    <artifactId>ezerbelcn-spring-boot-starter-autoconfigurer</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>ezerbelcn-spring-boot-starter-autoconfigurer</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

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

Starter模块增加三个文件

• HelloProperties

package com.ezerbelcn.starter;
import org.springframework.boot.context.properties.ConfigurationProperties;

@ConfigurationProperties(prefix = "ezerbelcn.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;
    }
}

• HelloService

package com.ezerbelcn.starter;

public class HelloService {

    HelloProperties helloProperties;

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

    public HelloProperties getHelloProperties() {
        return helloProperties;
    }

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

• HelloServiceAutoConfiguration

package com.ezerbelcn.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;

@EnableConfigurationProperties(HelloProperties.class)
@ConditionalOnWebApplication//web应用才会生效
@Configuration
public class HelloServiceAutoConfiguration {

    @Autowired
    HelloProperties helloProperties;

    @Bean
    public HelloService helloService(){
        HelloService service = new HelloService();
        service.setHelloProperties(helloProperties);
        return service;
    }
}

安装这两个模块

建立测试工程

引入自定义的starter

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

starter和stater的相应依赖都被引入进来了

全局配置文件，添加信息

最终测试

@RestController
public class HelloController {

    @Autowired
    HelloService helloService;

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

总结流程：

• starter

  作用：仅仅指定项目所需的各种依赖即可
  命名：xxx-spring-boot-starter

• auto-configure

  作用：

  • 提供自动配置类，内部包含@Bean方法以及其他装配方式，通常可以结合properties类读取配置文件内的信息。

  • 通常使用@EnableConfigurationProperties(xxxProperties.class)来标注这个配置类。

  • xxxProperties.class 类结合@ConfigurationProperties(prefix=“xxx.xxx”)来指明配置文件中对应信息的前缀。

  命名：xxx-spring-boot-starter-autoconfigure