SpringBoot7-自定义starter

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如何编写

理清依赖

自动配置

@Configuration 指定这个是配置类
@ConditionalOnxxx 在某些条件下才生效
@AutoConfigureAfter 指定自动配置类的顺序
@Bean 给IOC加组件
@ConfiguretionProperties 结合相关的xxxProperties配置类来绑定配置
@EnableConfigurationProperties 让xxxProperties生效加入到容器中
讲自动配置类配置在META-INF/spring.factories中

自动配置设置

启动器只做依赖导入，自动配置专门用一个模块来写，让启动器依赖自动配置，别人就只需要引入启动器即可

开始操作

先创建空工程，在里面创建两个modules，一个是空的maven，另一个是空的springboot

maven工程

导入一个依赖就可以了

<?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>org.example</groupId>
    <artifactId>hello-spring-boot-starter</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>com.example</groupId>
            <artifactId>hello-spring-boot-starter-autoconfigure</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
    </dependencies>

</project>

springboot自动配置

给他多删些东西

<?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>2.2.6.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>hello-spring-boot-starter-autoconfigure</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>hello-spring-boot-starter-autoconfigure</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>

增加配置类

配置类会被放入到容器中

package com.wsx.starter;

import org.springframework.boot.context.properties.ConfigurationProperties;

@ConfigurationProperties(prefix = "wsx.hello")
public class HelloProperties {
    String prefix;
    String suffix;

    public String getPrefix() {
        return prefix;
    }

    public String getSuffix() {
        return suffix;
    }

    public void setPrefix(String prefix) {
        this.prefix = prefix;
    }

    public void setSuffix(String suffix) {
        this.suffix = suffix;
    }
}

增加service类

service借助配置提供函数服务

package com.wsx.starter;

import org.springframework.beans.factory.annotation.Autowired;

public class HelloService {
    HelloProperties helloProperties;

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

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

增加自动配置类

自动配置类从IOC容器中取出配置类，绑定并注入service类提供服务

package com.wsx.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
@EnableConfigurationProperties(HelloProperties.class)
public class HelloServiceAutoConfigueation {
    @Autowired
    HelloProperties helloProperties;
    @Bean
    public HelloService helloService(){
        HelloService helloService = new HelloService();
        helloService.setHelloProperties(helloProperties);
        return helloService;
    }
}

最后增加spring.factories

把自动配置类交给springboot

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.wsx.starter.HelloServiceAutoConfigueation

打包

先打包starter-autocinfigure，然后打包starter

测试

新建项目，导入依赖，创建controller

package com.wsx.springbootstartertest.controller;

import com.wsx.starter.HelloService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
public class MyController {
    @Autowired
    HelloService helloService;

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

}

编写配置文件

wsx.hello.prefix=hello prefix
wsx.hello.suffix=hello suffix

测试即可

@ConfigurationProperties 不能缺少下面这个依赖，否则不会自动处理配置的提示

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-configuration-processor</artifactId>
    <optional>true</optional>
    <scope>compile</scope>
</dependency>