SpringBoot 自定义 starter

素颜马尾好姑娘i 2022-01-20 11:49 376阅读 0赞

## 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;
            }
        }
    }
    复制代码

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,\
    复制代码

#### 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>
    复制代码

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>
    复制代码

关于web的一些自动配置都写在了这里 ，所以我们有以下总结：

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
    复制代码

#### 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 ####

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/> 
    	</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</artifactId>
    		</dependency>
    
    	</dependencies>
    
    
    </project>
    
    复制代码

#### 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;
        }
    
    }
    
    复制代码

#### 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();
        }
    }
    
    复制代码

#### 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;
        }
    
    
    }
    
    复制代码

#### 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
    复制代码

到这儿，我们的配置自定义的starter就写完了 ，我们把 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/> 
    	</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>
    
    		
    		<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>
    
    复制代码

### 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 + " , " );
        }
    
    }
    
    复制代码

### 3. application.properties ###

gf.hello.prefix = hi
    gf.hello.suffix = what's up man ? 复制代码

我运行项目访问 [http://127.0.0.1:8080/hello/zhangsan，结果如下：][http_127.0.0.1_8080_hello_zhangsan]

hi-zhangsan , what's up man ? 复制代码

源码下载: [github.com/gf-huanchup…][github.com_gf-huanchup]

[http_127.0.0.1_8080_hello_zhangsan]: https://link.juejin.im?target=http%3A%2F%2F127.0.0.1%3A8080%2Fhello%2Fzhangsan%25EF%25BC%258C%25E7%25BB%2593%25E6%259E%259C%25E5%25A6%2582%25E4%25B8%258B%25EF%25BC%259A
[github.com_gf-huanchup]: https://link.juejin.im?target=https%3A%2F%2Fgithub.com%2Fgf-huanchupk%2FSpringBootLearning