SpringBoot 使用 @Value 注解读取配置文件给静态变量赋值

1、application.properties 配置文件

[email protected]
mail.password=xue
mail.host=smtp.163.com
mail.smtp.auth=true

2、给普通变量赋值，直接在变量上添加 @Value 注解

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

public class MailConfig {
    @Value("${mail.username}")
    private String username;
    @Value("${mail.password}")
    private String password;
    @Value("${mail.host}")
    private String host;
}

3、给静态变量赋值，直接在静态变量上添加 @Value 注解无效

4、给静态变量赋值

1、使用 set 方法

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

@Component
public class MailConfig {
    public static String username;
    public static String password;
    public static String host;

    @Value("${mail.username}")
    public void setUsername(String username) {
        this.username = username;
    }

    @Value("${mail.password}")
    public void setPassword(String password) {
        this.password = password;
    }

    @Value("${mail.host}")
    public void setHost(String host) {
        this.host = host;
    }
}

2、使用 @PostConstruct（推荐使用）

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

import javax.annotation.PostConstruct;

@Component
public class MailConfig {
    public static String USERNAME;
    public static String PASSWORD;
    public static String HOST;

    @Value("${mail.username}")
    private String username;
    @Value("${mail.password}")
    private String password;
    @Value("${mail.host}")
    private String host;

    @PostConstruct
    public void init() {
        USERNAME = username;
        PASSWORD = password;
        HOST = host;
    }
}