自定义SpringBoot Starter

终于不那么忙

(一)自定义Starter

1.创建maven项目

2.引入自动配置maven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 http://maven.apache.org/xsd/maven-4.0.0.xsd">
	<modelVersion>4.0.0</modelVersion>

	<groupId>cn.zack</groupId>
	<artifactId>helloworld-spring-boot-starter</artifactId>
	<version>1.0.0-RELEASE</version>
	<packaging>jar</packaging>

	<name>helloworld-spring-boot-starter</name>
	<description>自定义starter</description>

	<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-autoconfigure</artifactId>
			<version>2.0.0.RELEASE</version>
		</dependency>
		<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-configuration-processor</artifactId>
			<version>2.0.0.RELEASE</version>
			<optional>true</optional>
		</dependency>
	</dependencies>

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

</project>

3.编写spring.factories配置文件

指定自动装配配置类路径

org.springframework.boot.autoconfigure.EnableAutoConfiguration=cn.zack.UserServiceAutoConfiguration

4.编写UserProperties类

指定从配置文件中读取属性进行装配的前缀

package cn.zack;

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

@ConfigurationProperties(prefix = "spring.user")
public class UserProperties {
    private String username;
    private int age;
    private String gender;

    // todo get set constructor
}

5.编写UserService业务类

package cn.zack;

public class UserService {
    private UserProperties userProperties;

    public UserService() {
    }

    public UserService(UserProperties userProperties) {
        this.userProperties = userProperties;
    }

    public void hello(){
        System.out.println(userProperties.getUsername() + "\n" + userProperties.getAge() + "\n" + userProperties.getGender());
    }
}

6.编写自动装配配置类UserServiceAutoConfiguration

package cn.zack;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * ConditionalOnClass  当类路径classpath下有指定的类的情况下进行自动配置
 * ConditionalOnProperty  当配置文件中example.service.enabled=true时进行自动配置，如果没有设置此值就默认使用matchIfMissing对应的值
 * ConditionalOnBean  当容器(Spring Context)中有指定的Bean的条件下
 * ConditionalOnMissingBean  当容器(Spring Context)中没有指定Bean的情况下进行自动配置
 */
@Configuration
@EnableConfigurationProperties(UserProperties.class)
@ConditionalOnClass(UserService.class)
@ConditionalOnProperty(prefix = "spring.user", value = "enabled", matchIfMissing = true)
public class UserServiceAutoConfiguration {
    @Autowired
    private UserProperties userProperties;

    @Bean
    @ConditionalOnMissingBean(UserService.class)
    public UserService userService(){
        UserService userService = new UserService(userProperties);
        return userService;
    }
}

7.maven打包

mvn clean install -DskipTests

(二)使用自定义Starter

1.新建一个springboot项目, 引入自定义starter的maven依赖

<dependency>
    <groupId>cn.zack</groupId>
    <artifactId>helloworld-spring-boot-starter</artifactId>
    <version>1.0.0-RELEASE</version>
</dependency>

2.yml配置文件中配置自定义starter的属性

3.注入自定义starter的UserService

    @Autowired
    UserService userService;

    @Test
    public void test() {
        userService.hello();
    }