Spring Boot 自定义starter的示例代码

springboot 个人感觉特点：

1）众多库的集合（各种starter），方便快速构建应用系统。

2）自动配置spring（通过autoconfiguration机制），简化配置，也方便扩展新的starter。

3）内嵌web容器，无需war部署。

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

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[/code]

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[/code]

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

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。