Spring Boot 6-SpringBoot运行原理实现

Spring Boot自动配置实战

1、新建Spring-boot-starter-hello项目。

2、新建HelloService.java

package com.tzp.helloworld.helloservice;

public class HelloService {

    private String msg;

    public String sayHello() {
        return "=======>>" + msg;
    }

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }

}

2、新建HelloServiceProperties.java

package com.tzp.helloworld.helloproperties;

import org.springframework.boot.context.properties.ConfigurationProperties;

@ConfigurationProperties(prefix = "hello")
public class HelloServiceProperties {

    private static final String MSG = "World";
    
    private String msg = MSG;

    public String getMsg() {
        return msg;
    }

    public void setMsg(String msg) {
        this.msg = msg;
    }
    
}

3、新建HelloServiceAutoConfigration.java

package com.tzp.helloworld.helloServiceConfigration;

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.ConditionalOnMissingClass;
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;

import com.tzp.helloworld.helloproperties.HelloServiceProperties;
import com.tzp.helloworld.helloservice.HelloService;

@Configuration
@EnableConfigurationProperties(HelloServiceProperties.class)
@ConditionalOnClass(HelloService.class)
@ConditionalOnProperty(prefix = "hello",value = "enabled",matchIfMissing = true)
public class HelloServiceAutoConfigration {

    @Autowired
    private HelloServiceProperties helloServiceProperties;
    
    @Bean
    @ConditionalOnMissingBean(HelloService.class)
    public HelloService helloService() {
        HelloService helloService = new HelloService();
        helloService.setMsg(helloServiceProperties.getMsg());
        return helloService;
    }
    
}

4、mvn install将项目打成jar包，并将jar包添加到本地maven仓库。
5、接下来我们就可以在别的工程上使用该jar包了。

<dependency>
    <groupId>com.tzp</groupId>
    <artifactId>spring-boot-starter-hello</artifactId>
　　<version>1.0.0</version>
</dependency>

hello:
  msg: 唐增平的springboot

package com.tzp.helloworld.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import com.tzp.helloworld.helloservice.HelloService;

@RestController
public class HelloSpringBoot {

    @Value("${melo.name}")
    private String name;

    @Autowired
    private HelloService helloService;

    @RequestMapping("/")
    public String hello() {
        return "hello spring boot " + name + helloService.getMsg();
    }

}

6、运行项目并访问。