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一、簡介
SpringBoot 最強大的功能就是把我們常用的場景抽取成了一個個starter(場景啟動器),我們通過引入SpringBoot 為我提供的這些場景啟動器,我們再進行少量的配置就能使用相應的功能。即使是這樣,SpringBoot也不能囊括我們所有的使用場景,往往我們需要自定義starter,來簡化我們對SpringBoot的使用。
下面話不多說了,來一起看看詳細的介紹吧
二、如何自定義starter
1.實例
如何編寫自動配置 ?
我們參照@WebMvcAutoConfiguration為例,我們看看需要準備哪些東西,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; } } }
我們可以抽取到我們自定義starter時,同樣需要的一些配置。
@Configuration //指定這個類是一個配置類 @ConditionalOnXXX //指定條件成立的情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需要將自動配置類,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,\
模式
我們參照 spring-boot-starter 我們發現其中沒有代碼:
我們在看它的pom中的依賴中有個 springboot-starter
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency>
我們再看看 spring-boot-starter 有個 spring-boot-autoconfigure
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-autoconfigure</artifactId> </dependency>
關于web的一些自動配置都寫在了這里 ,所以我們有以下總結:
啟動器starter只是用來做依賴管理
需要專門寫一個類似spring-boot-autoconfigure的配置模塊
用的時候只需要引入啟動器starter,就可以使用自動配置了
命名規范
官方命名空間
自定義命名空間
三、自定義starter實例
我們需要先創建兩個工程 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> <!-- 啟動器 --> <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>
同時刪除 啟動類、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,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; } }
5. spring.factories
在 resources 下創建文件夾 META-INF 并在 META-INF 下創建文件 spring.factories ,內容如下:
# Auto Configure org.springframework.boot.autoconfigure.EnableAutoConfiguration=\ com.gf.service.HelloServiceAutoConfiguration
到這兒,我們的配置自定義的starter就寫完了 ,我們把 hello-spring-boot-starter-autoconfigurer、hello-spring-boot-starter 安裝成本地jar包。
三、測試自定義starter
我們創建個項目 hello-spring-boot-starter-test,來測試系我們寫的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>
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 ?
我運行項目訪問 http://127.0.0.1:8080/hello/zhangsan,結果如下:
hi-zhangsan , what's up man ?
源碼下載: https://github.com/gf-huanchupk/SpringBootLearning
總結
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