代码
pom.xml：
<?xml version="1.0" encoding="UTF-8"?>
<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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>2.6.2</version>
</parent>
<packaging>jar</packaging>
<groupId>com.kaven</groupId>
<artifactId>springboot</artifactId>
<version>0.0.1-SNAPSHOT</version>
<name>springboot</name>
<description>springboot</description>
<properties>
<java.version>1.8</java.version>
</properties>
<dependencies>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>
<dependency>
<groupId>org.projectlombok</groupId>
<artifactId>lombok</artifactId>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-maven-plugin</artifactId>
</plugin>
</plugins>
</build>
</project>
配置类：
package com.kaven.springboot.config;
import lombok.Setter;
import lombok.ToString;
import org.springframework.boot.context.properties.ConfigurationProperties;
import java.util.List;
import java.util.Map;
import java.util.Set;
@ConfigurationProperties(prefix = "user")
@Setter
@ToString
public class UserProperties {
private String username;
private String password;
private Set<String> hobbies;
private Map<String, Integer> scores;
private List<UserToken> userToken;
}
UserToken类：
package com.kaven.springboot.config;
import lombok.Setter;
import lombok.ToString;
@Setter
@ToString
public class UserToken {
private String token;
}
接口：
package com.kaven.springboot.controller;
import com.kaven.springboot.config.UserProperties;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.annotation.Resource;
@RestController
public class ConfigController {
@Resource
private UserProperties userProperties;
@GetMapping("/config")
public String getConfig() {
return userProperties.toString();
}
}
application.properties：
user.username="kaven"
user.password="itkaven"
user.hobbies[0]="A"
user.hobbies[1]="B"
user.hobbies[2]="C"
user.scores.mathematics=145
user.scores.english=80
user.user-token[0].token="A"
user.user-token[1].token="B"
user.user-token[2].token="C"
启动类：
package com.kaven.springboot;
import com.kaven.springboot.config.UserProperties;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.EnableConfigurationProperties;
@SpringBootApplication
@EnableConfigurationProperties(value = {UserProperties.class})
//@ConfigurationPropertiesScan(basePackageClasses = {UserProperties.class})
public class SpringbootApplication {
public static void main(String[] args) {
SpringApplication application = new SpringApplication(SpringbootApplication.class);
application.run(args);
}
}
下面这两个注解都可以使得Spring Boot基于被@ConfigurationProperties注解修饰的类创建bean，因此UserProperties实例可以自动注入到控制器中。
@EnableConfigurationProperties(value = {UserProperties.class})
@ConfigurationPropertiesScan(basePackageClasses = {UserProperties.class})
而@ConfigurationPropertiesScan注解还可以指定要被扫描的包数组。
@ConfigurationPropertiesScan(basePackages = {"com.kaven.springboot.config"})
启动应用，访问http://localhost:8080/config。
效果符合预期。
构造器绑定
Spring Boot将配置文件中的配置自动绑定到配置类，无非就是通过反射等手段，创建配置类实例，而配置项需要绑定到配置类实例的属性，这一般通过属性的set方法或者构造器来实现，上面的演示是通过set方法来进行绑定，这是@Setter注解的效果。
@Setter
如果需要通过构造器将配置项绑定到配置类实例的属性，可以使用@ConstructorBinding注解。
package com.kaven.springboot.config;
import lombok.ToString;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.ConstructorBinding;
import java.util.List;
import java.util.Map;
import java.util.Set;
@ConfigurationProperties(prefix = "user")
@ToString
@ConstructorBinding
public class UserProperties {
private String username;
private String password;
private Set<String> hobbies;
private Map<String, Integer> scores;
private List<UserToken> userToken;
public UserProperties(String username,
String password,
Set<String> hobbies,
Map<String, Integer> scores,
List<UserToken> userToken) {
this.username = username;
this.password = password;
this.hobbies = hobbies;
this.scores = scores;
this.userToken = userToken;
}
}
使用@ConstructorBinding注解修饰类的问题在于类中可能有多个构造器，如果出现这种情况就会有问题。
package com.kaven.springboot.config;
import lombok.ToString;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.ConstructorBinding;
import java.util.List;
import java.util.Map;
import java.util.Set;
@ConfigurationProperties(prefix = "user")
@ToString
@ConstructorBinding
public class UserProperties {
private String username;
private String password;
private Set<String> hobbies;
private Map<String, Integer> scores;
private List<UserToken> userToken;
public UserProperties() {}
public UserProperties(String username,
String password,
Set<String> hobbies,
Map<String, Integer> scores,
List<UserToken> userToken) {
this.username = username;
this.password = password;
this.hobbies = hobbies;
this.scores = scores;
this.userToken = userToken;
}
}
因为Spring Boot不知道调用哪个构造器。
可以将@ConstructorBinding注解修饰在构造器上。
package com.kaven.springboot.config;
import lombok.ToString;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.ConstructorBinding;
import java.util.List;
import java.util.Map;
import java.util.Set;
@ConfigurationProperties(prefix = "user")
@ToString
public class UserProperties {
private String username;
private String password;
private Set<String> hobbies;
private Map<String, Integer> scores;
private List<UserToken> userToken;
public UserProperties() {}
@ConstructorBinding
public UserProperties(String username,
String password,
Set<String> hobbies,
Map<String, Integer> scores,
List<UserToken> userToken) {
this.username = username;
this.password = password;
this.hobbies = hobbies;
this.scores = scores;
this.userToken = userToken;
}
}
结合@PropertySource
SourceConfig类：
package com.kaven.springboot.config;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.PropertySource;
@Configuration
@PropertySource(value = "classpath:/static/user.properties")
public class SourceConfig {}
效果符合预期，@ConfigurationProperties实现配置自动绑定就介绍到这里，如果博主有说错的地方或者大家有不同的见解，欢迎大家评论补充。