SpringBoot中@ConfigurationProperties实现配置自动绑定的方法

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@ConstructorBindingpublic class UserProperties {<!--{cke_protected}{C}%3C!%2D%2D%20%2D%2D%3E--> private String username; private String password; private Set<String> hobbies; private Map<String, Integer> scores; private List<UserToken> userToken; public UserProperties() {<!--{cke_protected}{C}%3C!%2D%2D%20%2D%2D%3E-->} public UserProperties(String username, String password, Set<String> hobbies, Map<String, Integer> scores, List<UserToken> userToken) {<!--{cke_protected}{C}%3C!%2D%2D%20%2D%2D%3E--> 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，,更多相关SpringBoot @ConfigurationProperties 自动绑定内容请搜索猪先飞以前的文章或继续浏览下面的相关文章希望大家以后多多支持猪先飞！