SpringBoot2.x学习（二）：为属性注入配置文件中的值：@ConfigurationProperties注解的使用

一、@ConfigurationProperties 简单介绍

通过使用 @ConfigurationProperties 注解在类上，在SpringBoot 全局配置文件就可以为类的对象的属性注入对应的值。

二、@ConfigurationProperties 使用示范

1、创建两个 javaBean

Demo.java

package com.example.springbootboot02config.bean;

import java.util.Date;
import java.util.List;
import java.util.Map;

/**
 * @author liyanan
 * @date 2019/12/16 13:43
 */
public class Demo {
       private String lastName;

    private Integer age;

    private Double salary;

    private Boolean boss;

    private Date birthday;

    private Map<String, Object> map;

    private List<String> list;

    private DataDemo dataDemo;

    public String getLastName() {
        return lastName;
    }

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

    public Integer getAge() {
        return age;
    }

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

    public Double getSalary() {
        return salary;
    }

    public void setSalary(Double salary) {
        this.salary = salary;
    }

    public Boolean getBoss() {
        return boss;
    }

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

    public Date getBirthday() {
        return birthday;
    }

    public void setBirthday(Date birthday) {
        this.birthday = birthday;
    }

    public Map<String, Object> getMap() {
        return map;
    }

    public void setMap(Map<String, Object> map) {
        this.map = map;
    }

    public List<String> getList() {
        return list;
    }

    public void setList(List<String> list) {
        this.list = list;
    }
    
    public DataDemo getDataDemo() {
        return dataDemo;
    }

    public void setDataDemo(DataDemo dataDemo) {
        this.dataDemo = dataDemo;
    }

    @Override
    public String toString() {
        return "Demo{" +
                "lastName='" + lastName + '\'' +
                ", age=" + age +
                ", salary=" + salary +
                ", boss=" + boss +
                ", birthday=" + birthday +
                ", map=" + map +
                ", list=" + list +
                ", dataDemo=" + dataDemo +
                '}';
    }
}

DataDemo.java

package com.example.springbootboot02config.bean;

/**
 * @author liyanan
 * @date 2019/12/16 13:43
 */
public class DataDemo {
    private String name;

    private Integer age;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getAge() {
        return age;
    }

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

    @Override
    public String toString() {
        return "DataDemo{" +
                "name='" + name + '\'' +
                ", age=" + age +
                '}';
    }
}

2、在 SpringBoot 全局配置文件写入需要注入的值

2.1 application.yml 写法

demo:
  lastName: zhangsan
  age: 20
  salary: 10000
  boss: true
  birthday: 1888/08/08
  map:
    key1: value1
    key2: value2
  list:
    - one
    - two
    - three
  dataDemo:
    name: java
    age: 8

2.2 application.properties 写法

# 配置 demo 的值
demo.last-name=lisi
demo.age=30
demo.birthday=1989/9/12
demo.boss=false
demo.salary=23000
demo.map.key1=value1
demo.map.key2=value2
demo.list=one, two, three
demo.data-demo.name=zhangsan
demo.data-demo.age=8

此时，在全局配置文件写的值还没有被注入到对应的对象中，需要在类上加入对应的注解。

3、在类上加上 @ConfigurationProperties 注解

@ConfigurationProperties(prefix = "demo")
@Component
public class Demo {
	// ... 内容已省略
}

@ConfigurationProperties(prefix = “demo”)：匹配配置文件里前缀为 demo 的配置

@Component：加上该注解，Spring 容器中才可以找到该类

4、测试

@SpringBootTest
class SpringbootBoot02ConfigApplicationTests {

    @Autowired
    Demo demo;

    @Test
    void contextLoads() {
        System.out.println(demo);
    }
}

输出结果为：

Demo{lastName='zhangsan', age=20, salary=10000.0, boss=true, birthday=Wed Aug 08 00:00:00 CST 1888, map={key1=value1, key2=value2}, list=[one, two, three], dataDemo=DataDemo{name='java', age=8}}

如果发现其中哪个值你配置了，但是却没有成功注入，检查 JavaBean 是否属性对应的 set 方法。