SpringBoot自定義starter

SpringBoot 提供了衆多的starter簡化咱們開發，爲了更好地使用這些starter，瞭解其原理是很重要的，今天就來自定義一個starter。

1，如何自定義 

①，咱們首先要有一個意識，springboot本身適配的通常以：spring-boot-starter-xxx命名，好比：spring-boot-starter-amqp

②，本身去適配springboot通常以：xxx-spring-boot-starter命名，好比：mybatis-spring-boot-starter

③，springboot自動適配的在依賴時通常不用加版本號，自動適配springboot 的須要版本號。由於sprinboot根本就不知道它的版本

③，經過觀察mybatis-spring-boot-starter，咱們發現mybatis-spring-boot-starter並無java代碼，經過觀察其pom.xml咱們發現，它引入了mybatis-spring-boot-autoconfigure

④，因此咱們能夠仿照mybatis自定義咱們的starter

2，建立工程

①，建立一個空的mystart工程，新建兩個模塊，1，mystart；2，autoconfigurable

3，mystart模塊配置

①，mystart依賴於autoconfigurable模塊

<groupId>com.spring.start</groupId>
    <artifactId>mystart</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>com.spring.start.autoconfigurable</groupId>
            <artifactId>autoconfigurable</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
    </dependencies>

4，autoconfigurable工程代碼

①，pom.xml

<groupId>com.spring.start.autoconfigurable</groupId>
	<artifactId>autoconfigurable</artifactId>
	<version>0.0.1-SNAPSHOT</version>
	<packaging>jar</packaging>

	<name>autoconfigurable</name>
	<description>Demo project for Spring Boot</description>

	<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.0.RELEASE</version>
	</parent>

	<dependencies>
        <--依賴於springboot starter-->
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter</artifactId>
		</dependency>
	</dependencies>

②，編寫xxxProperties類，相似於ServerProperties

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

//這樣才能讀取到application.properties 中的相應配置
@ConfigurationProperties("spring.su")
public class SuProperties {

    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;
    }
}

③，編寫功能類

public class SuService {
    //這裏不用@Autowired注入，會在自動配置類注入時給設置，因此纔有setSuProperties 方法
    private SuProperties suProperties;

    public String hello(String name){
        return suProperties.getPrefix()+"--"+name+"=="+suProperties.getSuffix();
    }


    public SuProperties getSuProperties() {
        return suProperties;
    }

    public void setSuProperties(SuProperties suProperties) {
        this.suProperties = suProperties;
    }
}

④，編寫自動配置類

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;

//是個配置類
@Configuration
//在web應用中起效
@ConditionalOnWebApplication
//指明配置類，這樣SuProperties 才能被注入
@EnableConfigurationProperties({SuProperties.class})
public class SuAutoConfiguration {

    @Autowired
    private SuProperties suProperties;

    @Bean
    public SuService suService(){
        SuService suService = new SuService();
        suService.setSuProperties(suProperties);
        return suService;
    }
}

⑤，添加對應的 META-INF/spring.factories

⑥，spring.factories 內容，這樣springboot在啓動時會就掃描對應的AutoConfiguration,爲何會這樣你們知道嗎？參考

org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.spring.start.autoconfigurable.SuAutoConfiguration

5，mystart工程代碼

①，pom.xml 依賴於autoConfiguration 工程便可

<groupId>com.spring.start</groupId>
    <artifactId>mystart</artifactId>
    <version>1.0-SNAPSHOT</version>

    <dependencies>
        <dependency>
            <groupId>com.spring.start.autoconfigurable</groupId>
            <artifactId>autoconfigurable</artifactId>
            <version>0.0.1-SNAPSHOT</version>
        </dependency>
    </dependencies>

6，測試工程代碼編寫

①，pom.xml

<parent>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-parent</artifactId>
		<version>2.0.0.RELEASE</version>
	</parent>

	<dependencies>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-starter-web</artifactId>
		</dependency>
        <--依賴mystart 便可，mystart 會依賴autoconfigurable 工程，注意這裏要指定版本號-->
		<dependency>
			<groupId>com.spring.start</groupId>
			<artifactId>mystart</artifactId>
			<version>1.0-SNAPSHOT</version>
		</dependency>

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

②，application.properties

spring.su.prefix=小美女
spring.su.suffix=錯過了

③，測試類

import com.spring.start.autoconfigurable.SuService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class HomeController {

    @Autowired
    private SuService suService;

    @RequestMapping("/")
    public String index(){
        return suService.hello("小蘇");
    }
}

④，啓動工程，而後測試便可，

⑤，遺留問題，在application.properties 寫的中文會亂碼，暫時沒有找到解決的辦法，知道如何的同窗歡迎留言，感謝！！！