Spring Boot 自定義starter的示例代碼

更新時間：2018年11月22日 13:57:58 作者：一花一四季,一夢一世界

這篇文章主要介紹了Spring Boot 自定義starter的示例代碼，小編覺得挺不錯的，現(xiàn)在分享給大家，也給大家做個參考。一起跟隨小編過來看看吧

SpringBoot 個人感覺特點(diǎn)：

1）眾多庫的集合（各種Starter），方便快速構(gòu)建應(yīng)用系統(tǒng)。

2）自動配置spring（通過AutoConfiguration機(jī)制），簡化配置，也方便擴(kuò)展新的Starter。

3）內(nèi)嵌web容器，無需WAR部署。

創(chuàng)建一個用maven構(gòu)建的springboot項(xiàng)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>測試自定義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>

定義一個pojo用來接收properties中配置的信息

package com.xjw;                                                     
                                                             
import org.springframework.boot.context.properties.ConfigurationProperties;                        
                                                             
@ConfigurationProperties(prefix = "hello")                                        
public class HelloServiceProperteis {                                           
                                                             
  private String msg;                                                  
                                                             
  public String getMsg() {                                               
    return msg;                                                    
  }                                                           
                                                             
  public void setMsg(String msg) {                                           
    this.msg = msg;                                                  
  }                                                           
                                                             
}

@ConfigurationProperties：用來標(biāo)識這個pojo是一個用來接收指定前綴的資源配置值

prefix：表示在配置文件中配置項(xiàng)前綴[/code]

編寫一個Service用來對外提供服務(wù)

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;
  }

}

配置一個pojo用來讀取上面配置的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：標(biāo)識此類為一個spring配置類

@EnableConfigurationProperties(value = HelloServiceProperteis.class):啟動配置文件，value用來指定我們要啟用的配置類，可以有多個，多個時我們可以這么寫value={xxProperties1.class,xxProperteis2.class....}

@ConditionalOnClass(HelloService.class):表示當(dāng)classPath下存在HelloService.class文件時改配置文件類才有效

@ConditionalOnProperty(prefix = "hello", value = "enable", matchIfMissing = true):表示只有我們的配置文件是否配置了以hello為前綴的資源項(xiàng)值，并且在該資源項(xiàng)值為enable，如果沒有配置我們默認(rèn)設(shè)置為enable[/code]

最后在src/main/resources 文件夾下新建文件夾 META-INF，在新建的META-INF文件夾下新建spring.factories

在新建的spring.factories文件中配置自動啟動類為我們之前編寫的HelloAutoConfiguration 類

org.springframework.boot.autoconfigure.EnableAutoConfiguration=com.xjw.HelloAutoConfiguration

然后就可以在其他的spring-boot項(xiàng)目中使用我們剛剛新建的starter了,我們來測試一下

在新建一個spring-boot項(xiàng)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>測試自定義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>

然后我們直接在咋們的啟動類中中嘗試使用以下我們上面定義的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);
  }
}

接著我們修改測試項(xiàng)目中的application.properteis，加入如下配置：

debug=true
server.port=8888

#hello=enable
hello.msg=測試starter

最后啟動項(xiàng)目，觀察控制臺輸出的內(nèi)容中依賴的starter,從Positive matches下我們可以看到有這么一句：

HelloAutoConfiguration matched:
- @ConditionalOnClass found required class 'com.xjw.HelloService'; @ConditionalOnMissingClass did not find unwanted class (OnClassCondition)
- @ConditionalOnProperty (hello.enable) matched (OnPropertyCondition)

或者我們打開項(xiàng)目依賴樹也能找到我們的starter ,這說明spring已經(jīng)自動的啟動了我們的starter了，打開瀏覽器輸入地址：http://localhost:8888/將會看到如下結(jié)果