一.@ConfigurationProperties注解

使用该注解可以为Bean绑定application.yml中的属性值。以下就是使用@ConfigurationProperties注解的示例

项目结构
在这里插入图片描述
ServerConfig.class

package com.example.config;

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

@Component
@Data
@ConfigurationProperties("servers") //填写属性名上一级名称
public class ServerConfig {
    private String ipaddress;
    private int port;
    private  long timeout;
}

加载类

package com.example;

import com.alibaba.druid.pool.DruidDataSource;
import com.example.config.ServerConfig;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.Bean;

@SpringBootApplication
public class Springboot01ConfigurationApplication {

	@Bean
	@ConfigurationProperties(prefix = "datasource")
	public DruidDataSource dataSource(){
		DruidDataSource ds=new DruidDataSource();
//		ds.setDriverClassName("com.mysql.jdbc.driver");
		return ds;
	}

	public static void main(String[] args) {
		ConfigurableApplicationContext ctx = SpringApplication.run(Springboot01ConfigurationApplication.class, args);
		ServerConfig config = ctx.getBean(ServerConfig.class);
		System.out.println(config);
		DruidDataSource ds = ctx.getBean(DruidDataSource.class);
		System.out.println(ds.getDriverClassName());
	}

}

applicati.yml

servers:
  ipaddress: 127.0.0.1
  port: 2345
  timeout: -1

datasource:
  driverClassName: com.mysql.jdbc.Driver

补充知识：

1.@EnableConfigurationProperties注解与@ConfigurationProperties的关系：
可以在加载类中加载管理的配置，自动将配置类作为Bean。
2.解决如下问题在这里插入图片描述

在pom依赖中添加

<dependency>
			<groupId>org.springframework.boot</groupId>
			<artifactId>spring-boot-configuration-processor</artifactId>
			<optional>true</optional>
</dependency>

二、松散绑定

在application.yml中设置的属性会自动去掉下划线中划线将大写变为小写后与@ConfigurationProperties中的注解进行匹配，而@value不会这样匹配。这种匹配即为松散绑定。

servers:
  ipaddress: 127.0.0.1
  port: 2345
  timeout: -1

datasource:
  driverClassName: com.mysql.jdbc.Driver

三、常用计量单位的应用

Duration类型，表示时间范围单位
DataSize类型，表示存储空间单位

@DurationUnit(ChronoUnit.HOURS)
private Duration serverTimeOut;

@DataSizeUnit(DataUnit.MEGABYTES)
private DataSize dataSize;

四、数据校验

1.导入对应依赖

<dependency>
	<groupId>jakarta.validation</groupId>
	<artifactId>jakarta.validation-api</artifactId>
</dependency>

<dependency>
	<groupId>org.hibernate.validator</groupId>
	<artifactId>hibernate-validator</artifactId>
</dependency>

2.对实体类添加校验并对具体字段添加具体的验证

package com.example.config;

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.convert.DataSizeUnit;
import org.springframework.boot.convert.DurationUnit;
import org.springframework.stereotype.Component;
import org.springframework.util.unit.DataSize;
import org.springframework.util.unit.DataUnit;
import org.springframework.validation.annotation.Validated;

import javax.validation.Valid;
import javax.validation.constraints.Max;
import javax.validation.constraints.Min;
import java.time.Duration;
import java.time.temporal.ChronoUnit;

@Component
@Data
@Validated
@ConfigurationProperties("servers") //填写属性名上一级名称
public class ServerConfig {
    private String ipaddress;
    @Max(value = 8888,message = "最大值不能超过8888")
    @Min(value = 3,message = "最小值不能小于3")
    private int port;
    private  long timeout;

    @DurationUnit(ChronoUnit.HOURS)
    private Duration serverTimeOut;

    @DataSizeUnit(DataUnit.MEGABYTES)
    private DataSize dataSize;
}