Spring Boot框架中读取配置的几种方式

现在开发的主力语言已经从PHP转向Java，目前参与或负责公司的几个项目都是使用Spring Boot框架。用了Java之后，对比PHP就一个感觉：繁琐，Java比PHP繁琐的很！由于自己平时也在努力学习Java中，今天趁着有空闲来总结一下Spring Boot中读取配置的几种方式，加深一下自己的印象。

读取application文件
在application.yml或者properties文件中添加：

info.address=RPC
info.company=Spring
info.degree=high

1.@Value注解读取方式

import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Component;

@Component
public class InfoConfig {
    @Value("${info.address}")
    private String address;
    @Value("${info.company}")
    private String company;
    @Value("${info.degree}")
    private String degree;

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getCompany() {
        return company;
    }

    public void setCompany(String company) {
        this.company = company;
    }

    public String getDegree() {
        return degree;
    }

    public void setDegree(String degree) {
        this.degree = degree;
    }
}

2.@ConfigurationProperties注解读取方式

@Component
@ConfigurationProperties(prefix = "info")
public class InfoConfig {
    private String address;
    private String company;
    private String degree;

    public String getAddress() {
        return address;
    }

    public void setAddress(String address) {
        this.address = address;
    }

    public String getCompany() {
        return company;
    }

    public void setCompany(String company) {
        this.company = company;
    }

    public String getDegree() {
        return degree;
    }

    public void setDegree(String degree) {
        this.degree = degree;
    }
}

读取指定文件
资源目录下建立config/db-config.properties:

db.username=root
db.password=123456

1. @PropertySource+@Value注解读取方式

   @Component
   @PropertySource(value =  {
       "config/db-config.properties"}
   )
   public class DBConfig1 {
       @Value("${db.username}")
       private String username;
       @Value("${db.password}")
       private String password;
   
       public String getUsername() {
           return username;
       }
   
       public void setUsername(String username) {
           this.username = username;
       }
   
       public String getPassword() {
           return password;
       }
   
       public void setPassword(String password) {
           this.password = password;
       }
   }

   注意：@PropertySource不支持yml文件读取。

2. @PropertySource+@ConfigurationProperties注解读取方式

   @Component
   @ConfigurationProperties(prefix = "db")
   @PropertySource(value = {"config/db-config.properties"})
   public class DBConfig2 {
       private String username;
       private String password;
   
       public String getUsername() {
           return username;
       }
   
       public void setUsername(String username) {
           this.username = username;
       }
   
       public String getPassword() {
           return password;
       }
   
       public void setPassword(String password) {
           this.password = password;
       }
   }

3. Environment读取方式

   @Autowired
   private Environment environment;
   
   environment.getProperty("info.degree");

从以上示例来看，Spring Boot可以通过@PropertySource,@Value,@Environment,@ConfigurationProperties的相互配合来读取配置文件的内容，读取单个的配置Environment无疑是最霸道的方法。