Spring Boot配置类实例讲解

• application.properties

spring.application.name=demo
app.config.upload-addr=baidu.com
app.config.app-key=1234
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• AppConfigProperties

import lombok.Data;

@Data
public class AppConfigProperties {
    private String uploadAddr;
    private String appKey;
}
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• UploadComponent

import lombok.Data;
import lombok.extern.slf4j.Slf4j;

@Data
@Slf4j
public class UploadComponent {
    private AppConfigProperties appConfigProperties;
    public void upload(){
        log.info("app.config:{}",appConfigProperties);
    }
}
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• AppConfiguration

import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.web.client.RestTemplate;

@Configuration
public class AppConfiguration {

    //使用 @Value 注解注入配置文件中的spring.application.name属性的值到appName字段
    @Value("${spring.application.name}")
    public String appName;

    //定义一个Bean，RestTemplate的实例将会被Spring管理，BeanID=restTemplate
    @Bean
    public RestTemplate restTemplate() {return new RestTemplate();}

    //定义一个Bean，AppConfigProperties的实例将会被Spring管理
    //使用@ConfigurationProperties注解，将配置文件中以"app.config"为前缀的配置项自动绑定到AppConfigProperties
    @Bean
    @ConfigurationProperties(prefix = "app.config")
    public AppConfigProperties appConfigProperties() {return new AppConfigProperties();}

    @Bean
    public AppConfigProperties appConfigPropertiesNon() {return new AppConfigProperties();}

    //定义一个Bean UploadComponent的实例会被Spring管理
    //通过@Qualifier注解指定注入的appConfigProperties Bean的名称
    //确保注入的是我们刚刚定义的appConfigProperties Bean
    //在UploadComponent实例被创建后
    //设置其AppConfigProperties属性为我们注入的AppConfigProperties实例
    @Bean
    public UploadComponent uploadComponent(@Qualifier("appConfigProperties") AppConfigProperties properties) {
        UploadComponent uploadComponent = new UploadComponent();
        uploadComponent.setAppConfigProperties(properties);
        return uploadComponent;
    }
}

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• UploadController

import com.example.demo.config.UploadComponent;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import org.springframework.web.client.RestTemplate;

import javax.annotation.Resource;

@RestController
public class UploadController {
    @Resource
    private RestTemplate restTemplate;
    @Resource
    private UploadComponent uploadComponent;

    @GetMapping("/uploader")
    public void upload() {uploadComponent.upload();}
}
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