Spring Boot 自定义 starter

2023-01-18 08:06:14

一、简介

SpringBoot 最强大的功能就是把我们常用的场景抽取成了一个个starter（场景启动器），我们通过引入springboot 为我提供的这些场景启动器，我们再进行少量的配置就能使用相应的功能。即使是这样，springboot也不能囊括我们所有的使用场景，往往我们需要自定义starter，来简化我们对springboot的使用。

二、如何自定义starter

1.实例

如何编写自动配置 ？

我们参照@WebMvcAutoConfiguration为例，我们看看们需要准备哪些东西，下面是WebMvcAutoConfiguration的部分代码：

@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;

        }

    }

}

我们可以抽取到我们自定义starter时同样需要的一些配置。

@Configuration  //指定这个类是一个配置类

@ConditionalOnXXX  //指定条件成立的情况下自动配置类生效

@AutoConfigureOrder  //指定自动配置类的顺序

@Bean  //向容器中添加组件

@ConfigurationProperties  //结合相关xxxProperties来绑定相关的配置

@EnableConfigurationProperties  //让xxxProperties生效加入到容器中

自动配置类要能加载需要将自动配置类，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,\

模式

我们参照 spring-boot-starter 我们发现其中没有代码：

Spring Boot 自定义 starter

我们在看它的pom中的依赖中有个 springboot-starter

<dependency>

	<groupId>org.springframework.boot</groupId>

	<artifactId>spring-boot-starter</artifactId>

</dependency>

我们再看看 spring-boot-starter 有个 spring-boot-autoconfigure

<dependency>

	<groupId>org.springframework.boot</groupId>

	<artifactId>spring-boot-autoconfigure</artifactId>

</dependency>

关于web的一些自动配置都写在了这里 ，所以我们有总结：

启动器starter只是用来做依赖管理

需要专门写一个类似spring-boot-autoconfigure的配置模块

用的时候只需要引入启动器starter，就可以使用自动配置了

命名规范

官方命名空间

  • 前缀：spring-boot-starter-
  • 模式：spring-boot-starter-模块名
  • 举例：spring-boot-starter-web、spring-boot-starter-jdbc

自定义命名空间

  • 后缀：-spring-boot-starter
  • 模式：模块-spring-boot-starter
  • 举例：mybatis-spring-boot-starter

三、自定义starter实例

我们需要先创建两个工程 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>

	<!-- 启动器 -->

	<dependencies>

		<!-- 引入自动配置模块 -->

		<dependency>

			<groupId>com.gf</groupId>

			<artifactId>hello-spring-boot-starter-autoconfigurer</artifactId>

			<version>0.0.1-SNAPSHOT</version>

		</dependency>

	</dependencies>

</project>

同时删除 启动类、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，所有starter的基本配合 -->

		<dependency>

			<groupId>org.springframework.boot</groupId>

			<artifactId>spring-boot-starter</artifactId>

		</dependency>

	</dependencies>

</project>

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;

    }

}

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();

    }

}

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应该生效

@EnableConfigurationProperties(HelloProperties.class)

public class HelloServiceAutoConfiguration {

    @Autowired

    HelloProperties helloProperties;

    @Bean

    public HelloService helloService() {

        HelloService service = new HelloService();

        service.setHelloProperties( helloProperties  );

        return service;

    }

}

5. spring.factories

在 resources 下创建文件夹 META-INF 并在 META-INF 下创建文件 spring.factories ，内容如下：

# Auto Configure

org.springframework.boot.autoconfigure.EnableAutoConfiguration=\

com.gf.service.HelloServiceAutoConfiguration

到这儿，我们的配置自定义的starter就写完了 ，我们hello-spring-boot-starter-autoconfigurer、hello-spring-boot-starter 安装成本地jar包。

三、测试自定义starter

我们创建个项目 hello-spring-boot-starter-test，来测试系我们写的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>

		<!-- 引入自定义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>

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 + " , " );

    }

}

3. application.properties

gf.hello.prefix = hi

gf.hello.suffix = what's up man ?

我运行项目访问 http://127.0.0.1:8080/hello/zhangsan，结果如下：

hi-zhangsan , what's up man ?

源码下载: https://github.com/gf-huanchupk/SpringBootLearning

欢迎扫码或微信搜索公众号《程序员果果》关注我，关注有惊喜~

Spring Boot 自定义 starter

上一篇：Effective C++ 条款 50：了解new和delete的合理替换时机


下一篇：[转帖] SQL参数化的优点 CopyFrom https://www.cnblogs.com/-lzb/articles/4840671.html