Spring Boot 自定义starter

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：

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

https://github.com/gf-huanchupk/SpringBootLearning