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Spring Boot 自定义starter

创建一个用maven构建的springboot项目

pom文件配置如下:

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<?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>
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定义一个pojo用来接收properties中配置的信息

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 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                                                                                                                           
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@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

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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;
    }

}
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配置一个pojo用来读取上面配置的 HelloServiceProperteis 

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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;                                                                                                                
    }                                                                                                                                       
}                                                                                                                                           
                                                                                                                                            
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@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: 

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<?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>
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  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:

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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);
    }
}
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 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

 

 

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