spring boot 使用 starter 解决了很多配置问题, 但是, 他是怎么来解决这些问题的呢?
这里通过一个简单的例子, 来看一下, starter是怎么来设置默认配置的.
一. 建 starter 项目
自定义的starter, 项目命名规范是： 自定义名-spring-boot-starter
先来看一下, 我最后的目录结构
1. 修改pom.xml文件
<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>org.elvin</groupId> <artifactId>my-spring-boot-starter</artifactId> <version>1.0-SNAPSHOT</version> <packaging>jar</packaging> <name>my-spring-boot-starter</name> <url>http://maven.apache.org</url> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> </properties> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-autoconfigure</artifactId> <version>1.5.9.RELEASE</version> </dependency> <dependency> <groupId>junit</groupId> <artifactId>junit</artifactId> <version>3.8.1</version> <scope>test</scope> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.apache.maven.plugins</groupId> <artifactId>maven-compiler-plugin</artifactId> <version>2.3.2</version> <configuration> <source>1.8</source> <target>1.8</target> </configuration> </plugin> </plugins> </build> </project>
其实只是加入了 spring-boot-autoconfigure
App文件中的main方法, 我注释掉了, 这个在这里没有用到
2. 配置属性对应的接收文件
package org.elvin;
import org.springframework.boot.context.properties.ConfigurationProperties;/**
* author: Elvin
* Date: 2017/12/12 14:51
* Description:
*/
@ConfigurationProperties(prefix = "hello")
public class HelloServiceProperties {
//默认配置内容
private static final String MSG = "world";
private String msg = MSG;
public String getMsg() {
return msg;
}
public void setMsg(String msg) {
this.msg = msg;
}
}
3. 对外Service
package org.elvin;
/**
* author: Elvin
* Date: 2017/12/12 14:55
* Description:
*/
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;
}
}
4. 对外service与配置对应文件关联
package org.elvin;
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;
/**
* author: Elvin
* Date: 2017/12/12 14:59
* Description:
*/
@Configuration
@EnableConfigurationProperties(HelloServiceProperties.class)
@ConditionalOnClass(HelloService.class)
@ConditionalOnProperty(prefix = "hello", value="enabled", matchIfMissing =true )
public class HelloServiceAutoConfiguration {
@Autowired
private HelloServiceProperties helloServiceProperties;
@Bean
@ConditionalOnMissingBean(HelloService.class)
public HelloService helloService(){
HelloService helloService = new HelloService();
helloService.setMsg(helloServiceProperties.getMsg());
return helloService;
}
}
5. starter配置 : spring.factories
org.springframework.boot.autoconfigure.EnableAutoConfiguration=org.elvin.HelloServiceAutoConfiguration
做完这些之后, 通过 mvn clean install , 打包到maven库里面
二. spring boot 项目使用
新建一个spring boot 项目, 选择web即可.
目录结构：
先看一下引用pom.xml
<dependency> <groupId>org.elvin</groupId> <artifactId>my-spring-boot-starter</artifactId> <version>1.0-SNAPSHOT</version> </dependency>
再看一下HelloController
package org.elvin.learn.springboot.controller;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import org.elvin.*;
/**
* author: Elvin
* Date: 2017/12/12 15:34
* Description:
*/
@RestController
@RequestMapping("hello")
public class HelloController {
@Autowired
private HelloService helloService;
@RequestMapping("index")
public String index(){
return helloService.sayHello();
}
}
这里的 HelloService 就是 前面自定义 starter 里面的.
1. 结果: 未配置情况下, 应该是输出 hello world
2. 在配置文件中, 加入 hello.msg=hahahahahah
这个例子很简单, 只是显示一下主要的过程, 别的都是各插件自己的逻辑判断了.
参考资料：
JavaEE开发的颠覆者 Spring Boot实战
以上这篇spring boot 自定义starter的实现教程就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持脚本之家。
