SpringBoot 自定義 starter

1、簡介

SpringBoot 最強大的功能就是把咱們經常使用的場景抽取成了一個個starter（場景啓動器），咱們經過引入SpringBoot 爲我提供的這些場景啓動器，咱們再進行少許的配置就能使用相應的功能。即便是這樣，SpringBoot也不能囊括咱們全部的使用場景，每每咱們須要自定義starter，來簡化咱們對SpringBoot的使用。

2、如何自定義starter

1.實例

如何編寫自動配置 ？

咱們參照@WebMvcAutoConfiguration爲例，咱們看看須要準備哪些東西，下面是WebMvcAutoConfiguration的部分代碼：

@Configuration
@ConditionalOnWebApplication
@ConditionalOnClass({Servlet.class, DispatcherServlet.class, WebMvcConfigurerAdapter.class})
@ConditionalOnMissingBean({WebMvcConfigurationSupport.class})
@AutoConfigureOrder(-2147483638)
@AutoConfigureAfter({DispatcherServletAutoConfiguration.class, ValidationAutoConfiguration.class})
public class WebMvcAutoConfiguration {

	@Import({WebMvcAutoConfiguration.EnableWebMvcConfiguration.class})
    @EnableConfigurationProperties({WebMvcProperties.class, ResourceProperties.class})
    public static class WebMvcAutoConfigurationAdapter extends WebMvcConfigurerAdapter {

        @Bean
        @ConditionalOnBean({View.class})
        @ConditionalOnMissingBean
        public BeanNameViewResolver beanNameViewResolver() {
            BeanNameViewResolver resolver = new BeanNameViewResolver();
            resolver.setOrder(2147483637);
            return resolver;
        }
    }
}
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咱們能夠抽取到咱們自定義starter時,一樣須要的一些配置。

@Configuration  //指定這個類是一個配置類
@ConditionalOnXXX  //指定條件成立的狀況下自動配置類生效
@AutoConfigureOrder  //指定自動配置類的順序
@Bean  //向容器中添加組件
@ConfigurationProperties  //結合相關xxxProperties來綁定相關的配置
@EnableConfigurationProperties  //讓xxxProperties生效加入到容器中

自動配置類要能加載須要將自動配置類，配置在META-INF/spring.factories中
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
org.springframework.boot.autoconfigure.admin.SpringApplicationAdminJmxAutoConfiguration,\
org.springframework.boot.autoconfigure.aop.AopAutoConfiguration,\
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模式

咱們參照 spring-boot-starter 咱們發現其中沒有代碼：

咱們在看它的pom中的依賴中有個 springboot-starter

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter</artifactId>
</dependency>
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咱們再看看 spring-boot-starter 有個 spring-boot-autoconfigure

<dependency>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-autoconfigure</artifactId>
</dependency>
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關於web的一些自動配置都寫在了這裏 ，因此咱們有如下總結：

啓動器starter只是用來作依賴管理
須要專門寫一個相似spring-boot-autoconfigure的配置模塊
用的時候只須要引入啓動器starter，就可使用自動配置了
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命名規範

官方命名空間

• 前綴：spring-boot-starter-
• 模式：spring-boot-starter-模塊名
• 舉例：spring-boot-starter-web、spring-boot-starter-jdbc

自定義命名空間

• 後綴：-spring-boot-starter
• 模式：模塊-spring-boot-starter
• 舉例：mybatis-spring-boot-starter

3、自定義starter實例

咱們須要先建立兩個工程 hello-spring-boot-starter 和 hello-spring-boot-starter-autoconfigurer

1. hello-spring-boot-starter

1.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.gf</groupId>
	<artifactId>hello-spring-boot-starter</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>hello-spring-boot-starter</name>

	<!-- 啓動器 -->
	<dependencies>
		<!-- 引入自動配置模塊 -->
		<dependency>
			<groupId>com.gf</groupId>
			<artifactId>hello-spring-boot-starter-autoconfigurer</artifactId>
			<version>0.0.1-SNAPSHOT</version>
		</dependency>
	</dependencies>


</project>

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同時刪除 啓動類、resources下的文件，test文件。

2. hello-spring-boot-starter-autoconfigurer

1. 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.gf</groupId>
	<artifactId>hello-spring-boot-starter-autoconfigurer</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>hello-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>1.5.9.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，全部starter的基本配合 -->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter</artifactId>
		</dependency>

	</dependencies>


</project>

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2. HelloProperties

package com.gf.service;

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

@ConfigurationProperties(prefix = "gf.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;
    }

}

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3. HelloService

package com.gf.service;


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();
    }
}

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4. HelloServiceAutoConfiguration

package com.gf.service;

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應該生效
@EnableConfigurationProperties(HelloProperties.class)
public class HelloServiceAutoConfiguration {

    @Autowired
    HelloProperties helloProperties;

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


}

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5. spring.factories

在 resources 下建立文件夾 META-INF 並在 META-INF 下建立文件 spring.factories ，內容以下：

# Auto Configure
org.springframework.boot.autoconfigure.EnableAutoConfiguration=\
com.gf.service.HelloServiceAutoConfiguration
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到這兒，咱們的配置自定義的starter就寫完了 ，咱們把 hello-spring-boot-starter-autoconfigurer、hello-spring-boot-starter 安裝成本地jar包。

3、測試自定義starter

咱們建立個項目 hello-spring-boot-starter-test，來測試系咱們寫的stater。

1. 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.gf</groupId>
	<artifactId>hello-spring-boot-starter-test</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>hello-spring-boot-starter-test</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>1.5.9.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>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>

		<!-- 引入自定義starter -->
		<dependency>
			<groupId>com.gf</groupId>
			<artifactId>hello-spring-boot-starter</artifactId>
			<version>0.0.1-SNAPSHOT</version>
		</dependency>

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

	<build>
		<plugins>
			<plugin>
				<groupId>org.springframework.boot</groupId>
				<artifactId>spring-boot-maven-plugin</artifactId>
			</plugin>
		</plugins>
	</build>


</project>

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2. HelloController

package com.gf.controller;

import com.gf.service.HelloService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HelloController {

    @Autowired
    HelloService helloService;

    @GetMapping("/hello/{name}")
    public String hello(@PathVariable(value = "name") String name) {
        return helloService.sayHello( name + " , " );
    }

}

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3. application.properties

gf.hello.prefix = hi
gf.hello.suffix = what's up man ? 複製代碼

我運行項目訪問 http://127.0.0.1:8080/hello/zhangsan，結果以下：

hi-zhangsan , what's up man ? 複製代碼

源碼下載: github.com/gf-huanchup…