上一篇文章：https://createdpro.com/back/article/51000351764
上篇文章主要介绍了下springboot自动配置的特性，为了协助理解，我们可以自己定义一个bean交给springboot的自动配置进行注入。
本案例仅存在练习之用，无任何业务能力。
首先创建我们要自动配置的bean的类，这个类有一个销售苹果的业务方法：
package com.test.starter.apple;
import com.test.starter.autoconfig.AppleProperties;
public class SellApple {
private AppleProperties appleProperties;
public SellApple(AppleProperties appleProperties) {
this.appleProperties = appleProperties;
}
public void sell() {
System.out.println(appleProperties.getColor()
+ "色的苹果"
+ appleProperties.getWeight()
+ "斤重，价格是"
+ appleProperties.getPrice());
}
}
然后我们创建AppleProperties这个配置类，我们为每项属性设定了默认值，我们可以通过全局配置文件application.yml进行值得覆盖设置：
package com.test.starter.autoconfig;
import org.springframework.boot.context.properties.ConfigurationProperties;
@ConfigurationProperties(prefix = "createdpro.apple")
public class AppleProperties {
// 这里设置的值是默认值
// 当使用全局配置文件配置如上前缀时，该值会被覆盖
private Integer weight = 5;
private String color = "red";
private double price = 7.9;
public Integer getWeight() {
return weight;
}
public void setWeight(Integer weight) {
this.weight = weight;
}
public String getColor() {
return color;
}
public void setColor(String color) {
this.color = color;
}
public double getPrice() {
return price;
}
public void setPrice(double price) {
this.price = price;
}
}
接下来我们创建HttpClientAutoConfiguration这个类，实现配置的方法：
package com.test.starter.autoconfig;
import com.test.starter.apple.SellApple;
import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
@Configuration
@ConditionalOnClass({SellApple.class})
@EnableConfigurationProperties(AppleProperties.class)
public class AppleAutoConfiguration {
private final AppleProperties appleProperties;
public AppleAutoConfiguration(AppleProperties appleProperties) {
this.appleProperties = appleProperties;
}
@Bean
@ConditionalOnMissingBean(SellApple.class)
public SellApple sellApple() {
return new SellApple(appleProperties);
}
}
接下来创建测试类：
package com.test.stater;
import com.test.stater.apple.SellApple;
import org.junit.jupiter.api.Test;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
@SpringBootTest
class DemoApplicationTests {
@Autowired
private SellApple sellApple;
@Test
void sellTest() {
sellApple.sell();
}
}
运行测试方法，发现在应用被启动后，bean被自动配置并创建了。
接下来我们通过全局配置文件application.yml配置一下Apple的属性：
applcation.yml
createdpro:
apple:
weight: 10
color: green
再一次执行测试方法：
配置的默认值已经被覆盖了，使用了我们在全局配置applcation.yml中的值。