java SpringBoot 配置文件值注入的三种方式

.properties或.ymal直接注入

pom.xml中添加一个补丁，更方便得配置文件

 <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>

这个补丁可以在配置类属性的时候，自动提醒

根据实体类加自动注入注解

package com.example.demo.pojo;

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

@Component
@ConfigurationProperties(prefix = "person")
public class Person {
    String name;
    int age;

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

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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

在全局配置文件中直接进行配置

server:
  port: 8082
person:
  name: test
  age: 18

创建测试类进行测试

package com.example.demo;

import com.example.demo.pojo.Person;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.context.SpringBootTest;
import org.springframework.test.context.junit4.SpringRunner;

@RunWith(SpringRunner.class)
@SpringBootTest
public class DemoApplicationTests {
    @Autowired
    Person person;
    @Test
        public void contextLoads() {
        System.out.println(person);
    }

}

运行结果

@Value()注入

根据全局配置文件有选择性得挑选注入数据

根据实体类加@Value()

package com.example.demo.pojo;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;

@Component
public class Person {
    @Value("${person.name}")
    String name;
    @Value("#{11*11}")
    int age;

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

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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

运行结果

@PropertiesSource(@PropertiesSources)

该注解只能用于.properties,不可用于.ymal

添加额外的配置文件

根据实体类加@PropertySource()

package com.example.demo.pojo;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.PropertySource;
import org.springframework.stereotype.Component;

@Component
@PropertySource(value = {"classpath:person.properties"})
@ConfigurationProperties(prefix = "person")
public class Person {
    String name;
    int age;

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

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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

运行结果

@propertySources（）同理如下

配置文件

person.age=234

person.name=testPropertiesSources

实体类

package com.example.demo.pojo;

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

@Component
@PropertySource(value = {"classpath:person1.properties","classpath:person2.properties"})
@ConfigurationProperties(prefix = "person")
public class Person {
    String name;
    int age;

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

    public String getName() {
        return name;
    }

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

    public int getAge() {
        return age;
    }

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

运行结果

比较

	@ConfigurationProperties	@Value
功能	批量注入配置文件中的属性	一个个指定
松散绑定（松散语法）	支持	不支持
SpEL	不支持	支持
JSR303数据校验	支持	不支持
复杂类型封装	支持	不支持