创建一个用maven构建的springboot项目
pom文件配置如下：
<?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.xjw.springboot</groupId> <artifactId>hellostarter</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>hello-spring-boot-starter</name> <description>测试自定义starter</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.2.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</artifactId> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-configuration-processor</artifactId> <optional>true</optional> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
定义一个pojo用来接收properties中配置的信息
1 package com.xjw; 2 3 import org.springframework.boot.context.properties.ConfigurationProperties; 4 5 @ConfigurationProperties(prefix = "hello") 6 public class HelloServiceProperteis { 7 8 private String msg; 9 10 public String getMsg() { 11 return msg; 12 } 13 14 public void setMsg(String msg) { 15 this.msg = msg; 16 } 17 18 } 19
@ConfigurationProperties：用来标识这个pojo是一个用来接收指定前缀的资源配置值
prefix：表示在配置文件中配置项前缀
编写一个Service用来对外提供服务
package com.xjw; public class HelloService { private String msg; public String sayHello() { return "Hello " + msg; } public String getMsg() { return msg; } public void setMsg(String msg) { this.msg = msg; } }
配置一个pojo用来读取上面配置的 HelloServiceProperteis
package com.xjw; 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; @Configuration @EnableConfigurationProperties(value = HelloServiceProperteis.class) @ConditionalOnClass(HelloService.class) @ConditionalOnProperty(prefix = "hello", value = "enable", matchIfMissing = true) public class HelloAutoConfiguration { @Autowired private HelloServiceProperteis helloServiceProperteis; @Bean @ConditionalOnMissingBean(HelloService.class) public HelloService helloService() { HelloService helloService = new HelloService(); helloService.setMsg(helloServiceProperteis.getMsg()); return helloService; } }
@Configuration：标识此类为一个spring配置类
@EnableConfigurationProperties(value = HelloServiceProperteis.class):启动配置文件，value用来指定我们要启用的配置类，可以有多个，多个时我们可以这么写value={xxProperties1.class,xxProperteis2.class....}
@ConditionalOnClass(HelloService.class):表示当classPath下存在HelloService.class文件时改配置文件类才有效
@ConditionalOnProperty(prefix = "hello", value = "enable", matchIfMissing = true):表示只有我们的配置文件是否配置了以hello为前缀的资源项值，并且在该资源项值为enable，如果没有配置我们默认设置为enable
最后在src/main/resources 文件夹下新建文件夹 META-INF，在新建的META-INF文件夹下新建 spring.factories
在新建的spring.factories文件中配置自动启动类为我们之前编写的 HelloAutoConfiguration 类
org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.xjw.HelloAutoConfiguration
然后就可以在其他的spring-boot项目中使用我们刚刚新建的starter了,我们来测试一下
在新建一个spring-boot项目，pom.xml配置如下:
<?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.xjw.springboot</groupId> <artifactId>hellostarter.test</artifactId> <version>0.0.1-SNAPSHOT</version> <packaging>jar</packaging> <name>hello-spring-boot-starter-test</name> <description>测试自定义starter</description> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>1.5.2.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> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> </dependency> <dependency> <groupId>com.xjw.springboot</groupId> <artifactId>hellostarter</artifactId> <version>0.0.1-SNAPSHOT</version> </dependency> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build> </project>
然后我们直接在咋们的启动类中中尝试使用以下我们上面定义的starter提供的HelloService:
package com.xjw; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @RestController @SpringBootApplication public class HelloSpringBootStarterTestApplication { @Autowired private HelloService helloService; @RequestMapping("/") public String index() { return helloService.sayHello(); } public static void main(String[] args) { SpringApplication.run(HelloSpringBootStarterTestApplication.class, args); } }
接着我们修改测试项目中的application.properteis，加入如下配置：
debug=true server.port=8888
#hello=enable hello.msg=测试starter
最后启动项目，观察控制台输出的内容中依赖的starter,从Positive matches下我们可以看到有这么一句：
HelloAutoConfiguration matched: - @ConditionalOnClass found required class 'com.xjw.HelloService'; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition) - @ConditionalOnProperty (hello.enable) matched (OnPropertyCondition)
或者我们打开项目依赖树也能找到我们的starter ,这说明spring已经自动的启动了我们的starter了，打开浏览器输入地址：http://localhost:8888/将会看到如下结果
