SpringBoot中@ConfigurationProperties实现配置自动绑定代码方法

本篇文章小编给大家分享一下SpringBoot中@ConfigurationProperties实现配置自动绑定代码方法，文章代码介绍的很详细，小编觉得挺不错的，现在分享给大家供大家参考，有需要的小伙伴们可以来看看。

代码如下

pom.xml：

    4.0.0

    
        org.springframework.boot
        spring-boot-starter-parent
        2.6.2
    

    jar

    com.kaven
    springboot
    0.0.1-SNAPSHOT

    springboot
    springboot

    
        1.8
    

    
        
            org.springframework.boot
            spring-boot-starter-web
        
        
            org.projectlombok
            lombok
        
    
    
    
        
            
                org.springframework.boot
                spring-boot-maven-plugin
            
        
    

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 hobbies;
    private Map scores;
    private List 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 hobbies;
    private Map scores;
    private List userToken;

    public UserProperties(String username,
                          String password,
                          Set hobbies,
                          Map scores,
                          List 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@ConstructorBindingpublic class UserProperties { private String username; private String password; private Set hobbies; private Map scores; private List userToken; public UserProperties() {} public UserProperties(String username, String password, Set hobbies, Map scores, List 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 hobbies;
    private Map scores;
    private List userToken;

    public UserProperties() {}

    @ConstructorBinding
    public UserProperties(String username,
                          String password,
                          Set hobbies,
                          Map scores,
                          List 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