Spring Boot 的类文件中获取 propertites 文件值

application.properties
file 中快速获取

import org.springframework.stereotype.*;
import org.springframework.beans.factory.annotation.*;

@Component
public class MyBean {

    @Value("${name}")
    private String name;

    // ...

}

JavaBean properties binding

package com.example;

import java.net.InetAddress;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

import org.springframework.boot.context.properties.ConfigurationProperties;

@ConfigurationProperties("acme")
public class AcmeProperties {

    private boolean enabled;

    private InetAddress remoteAddress;

    private final Security security = new Security();

    public boolean isEnabled() { ... }

    public void setEnabled(boolean enabled) { ... }

    public InetAddress getRemoteAddress() { ... }

    public void setRemoteAddress(InetAddress remoteAddress) { ... }

    public Security getSecurity() { ... }

    public static class Security {

        private String username;

        private String password;

        private List<String> roles = new ArrayList<>(Collections.singleton("USER"));

        public String getUsername() { ... }

        public void setUsername(String username) { ... }

        public String getPassword() { ... }

        public void setPassword(String password) { ... }

        public List<String> getRoles() { ... }

        public void setRoles(List<String> roles) { ... }

    }
}

Constructor binding

package com.example;

import java.net.InetAddress;
import java.util.List;

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.context.properties.ConstructorBinding;
import org.springframework.boot.context.properties.DefaultValue;

@ConstructorBinding
@ConfigurationProperties("acme")
public class AcmeProperties {

    private final boolean enabled;

    private final InetAddress remoteAddress;

    private final Security security;

    public AcmeProperties(boolean enabled, InetAddress remoteAddress, Security security) {
        this.enabled = enabled;
        this.remoteAddress = remoteAddress;
        this.security = security;
    }

    public boolean isEnabled() { ... }

    public InetAddress getRemoteAddress() { ... }

    public Security getSecurity() { ... }

    public static class Security {

        private final String username;

        private final String password;

        private final List<String> roles;

        public Security(String username, String password,
                @DefaultValue("USER") List<String> roles) {
            this.username = username;
            this.password = password;
            this.roles = roles;
        }

        public String getUsername() { ... }

        public String getPassword() { ... }

        public List<String> getRoles() { ... }

    }

}

可以使用@DefaultValue指定默认值。

要使用构造函数绑定，必须使用@EnableConfigurationProperties或配置属性扫描启用该类。您不能使用构造函数绑定由常规Spring机制创建的bean(例如@Component bean、通过@Bean方法创建的bean或使用@Import加载的bean)

Enabling @ConfigurationProperties
-annotated types

Spring Boot提供了绑定@ConfigurationProperties类型并将它们注册为bean的基础设施。您可以逐个类地启用配置属性，也可以启用与组件扫描工作方式类似的配置属性扫描。

有时，用@ConfigurationProperties注释的类可能不适合扫描，

@Configuration(proxyBeanMethods = false)
@EnableConfigurationProperties(AcmeProperties.class)
public class MyConfiguration {
}

@SpringBootApplication
@ConfigurationPropertiesScan({ "com.example.app", "org.acme.another" })
public class MyApplication {
}

Using @ConfigurationProperties
-annotated types

要使用@ConfigurationProperties bean，您可以以与任何其他bean相同的方式注入它们，如下面的示例所示：

@Service
public class MyService {

    private final AcmeProperties properties;

    @Autowired
    public MyService(AcmeProperties properties) {
        this.properties = properties;
    }

    //...

    @PostConstruct
    public void openConnection() {
        Server server = new Server(this.properties.getRemoteAddress());
        // ...
    }

}

Externalized Configuration