@ConfigurationProperties、@EnableConfigurationProperties、@PropertySource的使用

参考博客: @ConfigurationProperties 注解使用姿势，这一篇就够了

一、注解的作用：

@ConfigurationProperties注解的作用就是获取我们配置的参数值，这些参数一般配置在application.properties或者application.yml中。

二、使@ConfigurationProperties生效的几种方式

1.使用在配置类上，使用@Configuration或者@Component注解，让component scan扫描到。

2.在java配置类中，使用@Bean返回被@ConfigurationProperties标注的配置类。

3.使用@EnableConfigurationProperties

三、代码：

application.yml配置：

server:
  port: 8080
  servlet:
    context-path: /helloSpring


website:
  name: bianchengbang
  url: www.biancheng.net
  pets:
    - dog
    - cat
    - pig

#将这些person属性全部映射到配置文件PersonProperties.java上
person:
  lastName: 张三
  age: 18
  boss: true
  pets:
    - dog
    - cat
    - pig

student:
  name: 王子奇
  age: 12

teacher:
  lesson: mathematics
  gender: female

PersonProperties.java:

package com.cy.config;

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

import java.util.List;

/**
 * 将配置文件中配置的每一个属性的值，映射到这个组件中
 */
@Configuration
@ConfigurationProperties(prefix = "person")
public class PersonProperties {

    private String lastName;

    private Integer age = 10;               //会被application.yml中配置的属性覆盖

    private Boolean boss = Boolean.FALSE;   //会被application.yml中配置的属性覆盖

    private List<String> pets;

    public Integer getAge() {
        return age;
    }

    public void setAge(Integer age) {
        this.age = age;
    }

    public Boolean getBoss() {
        return boss;
    }

    public void setBoss(Boolean boss) {
        this.boss = boss;
    }

    public List<String> getPets() {
        return pets;
    }

    public void setPets(List<String> pets) {
        this.pets = pets;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
}

StudentProperties.java:

package com.cy.config;

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

@Data
@ConfigurationProperties(prefix = "student")
public class StudentProperties {

    private String name;

    private Integer age;
}

TeacherProperties.java:

package com.cy.config;

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

@Data
@ConfigurationProperties(prefix = "teacher")
public class TeacherProperties {

    private String lesson;

    private String gender;
}

PropertiesConfig.java:

package com.cy.config;

import org.springframework.boot.context.properties.EnableConfigurationProperties;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

/**
 * 1.使用 @EnableConfigurationProperties 注解让我们的类（TeacherProperties）被 Spring Boot 所知道，
 *   激活@ConfigurationProperties
 */
@Configuration
@EnableConfigurationProperties(TeacherProperties.class)
public class PropertiesConfig {

    /**
     * 通过 Spring 的 Java Configuration 特性实现
     * 将StudentProperties配置属性@ConfigurationProperties激活
     */
    @Bean
    public StudentProperties studentProperties(){
        return new StudentProperties();
    }
}

测试代码，HelloController.java:

package com.cy.controller;

import com.cy.config.PersonProperties;
import com.cy.config.StudentProperties;
import com.cy.config.TeacherProperties;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.HashMap;
import java.util.Map;

@Controller
public class HelloController {

    @Autowired
    private PersonProperties personProperties;

    @Autowired
    private StudentProperties studentProperties;

    @Autowired
    private TeacherProperties teacherProperties;

    /**
     * value: 只支持基本数据类型的封装，例如字符串、布尔值、整数等类型。
     */
    @Value("${website.name}")
    private String webSiteName;

    @Value("${website.url}")
    private String webSiteUrl;

    @ResponseBody
    @RequestMapping("/hello")
    public String hello() {
        return "Hello World!";
    }

    /**
     * 将personProperties javabean配置属性打印出来
     * @return
     */
    @ResponseBody
    @RequestMapping("/personProperties")
    public Map<String, Object> personProperties() {
        Map<String, Object> map = new HashMap<>();
        map.put("lastName", personProperties.getLastName());
        map.put("age", personProperties.getAge());
        map.put("isBoss", personProperties.getBoss());
        map.put("pets", personProperties.getPets());
        return map;
    }

    @ResponseBody
    @RequestMapping("/getStudentProps")
    public Map<String, Object> getStudentProps() {
        Map<String, Object> map = new HashMap<>();
        map.put("student name", studentProperties.getName());
        map.put("student age", studentProperties.getAge());
        return map;
    }

    @ResponseBody
    @RequestMapping("/getTeacherProps")
    public Map<String, Object> getTeacherProps() {
        Map<String, Object> map = new HashMap<>();
        map.put("teacher lesson", teacherProperties.getLesson());
        map.put("teacher gender", teacherProperties.getGender());
        return map;
    }

    @ResponseBody
    @RequestMapping("/getWebSiteProps")
    public String getWebSiteProps() {
        return "webSiteName: " + webSiteName + " webSiteUrl: " + webSiteUrl;
    }

}

测试结果：

输入 http://localhost:8080/helloSpring/personProperties

{"pets":["dog","cat","pig"],"lastName":"张三","isBoss":true,"age":18}

输入 http://localhost:8080/helloSpring/getStudentProps

{"student age":12,"student name":"王子奇"}

输入 http://localhost:8080/helloSpring/getTeacherProps

{"teacher lesson":"mathematics","teacher gender":"female"}

输入 http://localhost:8080/helloSpring/getWebSiteProps

webSiteName: bianchengbang webSiteUrl: www.biancheng.net

四、@PropertySource使用

如果将所有的配置都集中到 application.properties 或 application.yml 中，那么这个配置文件会十分的臃肿且难以维护，因此我们通常会将与 Spring Boot 无关的配置（例如自定义配置）提取出来，写在一个单独的配置文件中，并在对应的 JavaBean 上使用 @PropertySource 注解指向该配置文件。

 

新建user.properties配置文件：放在classpath下面

user.firstName=lisi
user.age=10
user.birthDay=2000/10/04

UserProperties.java:

package com.cy.config;

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.PropertySource;
import org.springframework.stereotype.Component;

@PropertySource(value = "classpath:user.properties")//指向对应的配置文件
@Component
@ConfigurationProperties(prefix = "user")
@Data
public class UserProperties {
    private String firstName;

    private String age;

    private String birthDay;
}

HelloController.java中进行使用：

package com.cy.controller;

import com.cy.config.PersonProperties;
import com.cy.config.StudentProperties;
import com.cy.config.TeacherProperties;
import com.cy.config.UserProperties;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

import java.util.HashMap;
import java.util.Map;

@Controller
public class HelloController {

    @Autowired
    private UserProperties userProperties;


    @ResponseBody
    @RequestMapping("/getUserProps")
    public Map<String, Object> getUserProps() {
        Map<String, Object> map = new HashMap<>();
        map.put("user name", userProperties.getFirstName());
        map.put("user age", userProperties.getAge());
        map.put("user birthDay", userProperties.getBirthDay());
        return map;
    }

}

浏览器访问：http://localhost:8080/helloSpring/getUserProps，输出：

{"user name":"lisi","user birthDay":"2000/10/04","user age":"10"}

五、小记　　

1.这些注解的使用，代码中的例子比较简单。更多详细使用可见看考博客。

2.@Value的使用例子中也有，一般是在单个属性的使用中，可以看@Value和@ConfigurationProperties的区别。http://c.biancheng.net/spring_boot/config-bind.html

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