Java中带有单例的@Value

Question

我有一个ResourcesProperties.java类

@NoArgsConstructor
@PropertySource("classpath:config.properties")
@Component
public class ResourcesProperties {

    @Bean
    public static PropertySourcesPlaceholderConfigurer propertyConf() {
        return new PropertySourcesPlaceholderConfigurer();
    }

    public static ResourcesProperties instance;

    @Bean
    public static ResourcesProperties getInstance() {
        if (instance == null)
            instance = new ResourcesProperties();
        return instance;
    }

    @Getter
    @Value("${room.rightStatusRoom}")
    private static boolean rightStatusRoom;

    @Getter
    @Value("${room.countGuests}")
    private static int countGuests;
}

有一个"config.properties“属性文件

room.rightStatusRoom=true
room.countGuests=101

为什么，当使用@Value注解访问of字段时，它们不从属性文件中返回指定的值？

示例：

if(ResourcesProperties.getInstance().isRightStatusRoom()) { //returned false instead true
    //business-logic
}

Answer 1

我的解决方案是：

@NoArgsConstructor
@PropertySource("classpath:config.properties")
@Component
public class ResourcesProperties {

    @Getter
    @Value("${room.rightStatusRoom}")
    private boolean rightStatusRoom;

    @Getter
    @Value("${room.countGuests}")
    private int countGuests;
}

Answer 2

Spring不允许向静态对象注入值。因此您有两个选择，摆脱静态变量或调用设置静态变量的非静态设置器。更多信息可在此处找到：https://mkyong.com/spring/spring-inject-a-value-into-static-variables/

这些就是解决方案。

解决方案1：

@NoArgsConstructor
@PropertySource("classpath:config.properties")
@Component
public class ResourcesProperties {

    @Getter
    @Value("${room.rightStatusRoom}")
    private boolean rightStatusRoom;

    @Getter
    @Value("${room.countGuests}")
    private int countGuests;
}

解决方案2：

@NoArgsConstructor
@PropertySource("classpath:config.properties")
@Component
public class ResourcesProperties {

    @Getter
    private static boolean rightStatusRoom;

    @Getter
    private static int countGuests;

    @Value("${room.rightStatusRoom}")
    public void setRightStatusRoom(boolean rightStatusRoom) {
        this.rightStatusRoom = rightStatusRoom
    }

    @Value("${room.countGuests}")
    public void setCountGuests(int countGuests) {
        this.countGuests = countGuests
    }
}