SpringBoot 如何从配置文件读取值到对象中

目录

• 一、实现方式
• @ConfigurationProperties 注解
• @Valid注解
• 二、两者区别
• 三、代码演示
• 四、@PropertySource 读取指定配置文件
• 五、@ImportResource:导入Spring配置文件
• 六、思维导图

一、实现方式

@ConfigurationProperties 注解

（最好加上前缀prefix=“person”,标明是和配置文件中哪个开头的属性匹配）

推荐使用用在类上，从配置文件读取属性值，放到对象里面，复杂的结构也适用例如map,list，对象。支持校验:@Validated

@Valid注解

用在属性上，需要每个属性逐个绑定通过@value注解获取配置文件的值,不适合做复杂类型（map,list ,对象）值得获取不支持@Validated

二、两者区别

三、代码演示

使用@ConfigurationProperties注解

package com.wx.springboot20190911.demo.model;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
import org.springframework.validation.annotation.Validated;
import javax.validation.constraints.Email;
import java.util.Date;
import java.util.List;
import java.util.Map;
/**
 * 1.ConfigurationProperties注解 从配置文件读取属性值，放到对象里面
 * 2.通过@value注解获取配置文件的值
 */
@Component//perosn 需要纳入spring ioc 容器里
@ConfigurationProperties(prefix = "person")//使用前缀标明具体的属性
@Validated
public class Person {
    @Email
    String email;
    String hello;
    String name;
    int age;
    boolean boss;
    Date birth;
    Map<String,String> maps;
    List<String> list;
    Dog dog;
    @Override
    public String toString() {
        return "Person{" +
                "email='" + email + '\'' +
                ", hello='" + hello + '\'' +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", boss=" + boss +
                ", birth=" + birth +
                ", maps=" + maps +
                ", list=" + list +
                ", dog=" + dog +
                '}';
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public String getHello() {
        return hello;
    }
    public void setHello(String hello) {
        this.hello = hello;
    }
    public Dog getDog() {
        return dog;
    }
    public void setDog(Dog dog) {
        this.dog = dog;
    }
    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;
    }
    public boolean isBoss() {
        return boss;
    }
    public void setBoss(boolean boss) {
        this.boss = boss;
    }
    public Date getBirth() {
        return birth;
    }
    public void setBirth(Date birth) {
        this.birth = birth;
    }
    public Map<String, String> getMaps() {
        return maps;
    }
    public void setMaps(Map<String, String> maps) {
        this.maps = maps;
    }
    public List<String> getList() {
        return list;
    }
    public void setList(List<String> list) {
        this.list = list;
    }
}
package com.wx.springboot20190911.demo.model;
public class Dog {
    String name;
    String color;
    int age;
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getColor() {
        return color;
    }
    public void setColor(String color) {
        this.color = color;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    @Override
    public String toString() {
        return "Dog{" +
                "name='" + name + '\'' +
                ", color='" + color + '\'' +
                ", age=" + age +
                '}';
    }
}

使用@Value注解

package com.wx.springboot20190911.demo.model;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.stereotype.Component;
import org.springframework.validation.annotation.Validated;
import javax.validation.Valid;
import javax.validation.constraints.Email;
import java.util.Date;
import java.util.List;
import java.util.Map;
/**
 * 1.ConfigurationProperties注解 从配置文件读取属性值，放到对象里面，推荐使用，复杂的结构也适用例如map,list对象,
 * 支持 校验@Validated
 * 2.通过@value注解获取配置文件的值,不适合做复杂类型值得获取,不支持@Validated，支持
 */
@Component//perosn 需要纳入spring ioc 容器里
//@ConfigurationProperties(prefix = "person")
@Validated
public class Person1 {
    @Email
    @Value("${person1.email}")
    String email;
    @Value("${person1.hello}")
    String hello;
    @Value("${person1.name}")
    String name;
    @Value("#{12*3}")//支持计算
    int age;
    @Value("${person1.boss}")
    boolean boss;
    @Value("${person1.birth}")
    Date birth;
    Map<String,String> maps;
    List<String> list;
    Dog dog;
    public String getHello() {
        return hello;
    }
    public void setHello(String hello) {
        this.hello = hello;
    }
    public Dog getDog() {
        return dog;
    }
    public void setDog(Dog dog) {
        this.dog = dog;
    }
    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;
    }
    public boolean isBoss() {
        return boss;
    }
    public void setBoss(boolean boss) {
        this.boss = boss;
    }
    public Date getBirth() {
        return birth;
    }
    public void setBirth(Date birth) {
        this.birth = birth;
    }
    public Map<String, String> getMaps() {
        return maps;
    }
    public void setMaps(Map<String, String> maps) {
        this.maps = maps;
    }
    public List<String> getList() {
        return list;
    }
    public void setList(List<String> list) {
        this.list = list;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    @Override
    public String toString() {
        return "Person1{" +
                "email='" + email + '\'' +
                ", hello='" + hello + '\'' +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", boss=" + boss +
                ", birth=" + birth +
                ", maps=" + maps +
                ", list=" + list +
                ", dog=" + dog +
                '}';
    }
}

配置类（application.properties）代码

person.hello=luck
person.name=吴
#乱码的话 就setting设置下file encoding
person.list=ww,xx,rr
person.maps.k1=v1
person.maps.k2=v2
person.dog.name=cat
person.dog.color=red
person.dog.age=1
person.age=12
person.birth=2019/01/11
person.boss=false
person.email=www@qq.com
person1.hello=luck
person1.name=吴
#乱码的话 就setting设置下file encoding
person1.list=ww,xx,rr
person1.age=12
person1.birth=2019/01/11
person1.boss=false
person1.email=www

配置类(application.yml)代码:这种方式更加结构化

person:
  name: 霞
  age: 16
  boss : false
  birth: 2012/09/12
  maps: {k1: v1,k2: v2}
  list: [dog,cat ,house,rabbits]
  dog:
    name: ${person.hello}
    age: ${random.int(10)}
    color: white
  hello: yula

打印结果：使用第一种方式时，如果email不是"www@qq.com"这种格式，是不能运行成功的，但是使用@Value 不会校验，如下面是"www",一样能运行成功

Person{email='www@qq.com', hello='luck', name='吴', age=12, boss=false, birth=Fri Jan 11 00:00:00 CST 2019, maps={k1=v1, k2=v2}, list=[ww, xx, rr], dog=Dog{name='cat', color='red', age=1}}

Person1{email='www', hello='luck', name='吴', age=36, boss=false, birth=Fri Jan 11 00:00:00 CST 2019, maps=null, list=null, dog=null}

四、@PropertySource 读取指定配置文件

package com.wx.springboot20190911.demo.model;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.PropertySource;
import org.springframework.stereotype.Component;
import org.springframework.validation.annotation.Validated;
import javax.validation.constraints.Email;
import java.util.Date;
import java.util.List;
import java.util.Map;
/**
 * 1.ConfigurationProperties注解 从配置文件读取属性值，放到对象里面
 * 2.通过@value注解获取配置文件的值
 */
@PropertySource(value={"classpath:person.properties"})//指定读取person.properties配置文件
@Component//perosn 需要纳入spring ioc 容器里
@ConfigurationProperties(prefix = "person")//使用前缀标明具体的属性
@Validated
public class Person2 {
    @Email
    String email;
    String hello;
    String name;
    int age;
    boolean boss;
    Date birth;
    Map<String,String> maps;
    List<String> list;
    Dog dog;
    @Override
    public String toString() {
        return "Person{" +
                "email='" + email + '\'' +
                ", hello='" + hello + '\'' +
                ", name='" + name + '\'' +
                ", age=" + age +
                ", boss=" + boss +
                ", birth=" + birth +
                ", maps=" + maps +
                ", list=" + list +
                ", dog=" + dog +
                '}';
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
    public String getHello() {
        return hello;
    }
    public void setHello(String hello) {
        this.hello = hello;
    }
    public Dog getDog() {
        return dog;
    }
    public void setDog(Dog dog) {
        this.dog = dog;
    }
    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;
    }
    public boolean isBoss() {
        return boss;
    }
    public void setBoss(boolean boss) {
        this.boss = boss;
    }
    public Date getBirth() {
        return birth;
    }
    public void setBirth(Date birth) {
        this.birth = birth;
    }
    public Map<String, String> getMaps() {
        return maps;
    }
    public void setMaps(Map<String, String> maps) {
        this.maps = maps;
    }
    public List<String> getList() {
        return list;
    }
    public void setList(List<String> list) {
        this.list = list;
    }
}

这里虽然指定了读取person.properties配置文件，但是由于prefix=“person”,导致还是读取了application.properties配置文件，因为application.properties权限最高，要想读取person.properties配置文件，就得改前缀名，例如改成prefix=“person2” person.properties配置文件的内容如下：

没改前缀名的结果演示：

Person{email='www@qq.com', hello='luck', name='吴', age=12, boss=false, birth=Fri Jan 11 00:00:00 CST 2019, maps={k1=v1, k2=v2}, list=[ww, xx, rr], dog=Dog{name='cat', color='red', age=1}}

Person1{email='www', hello='luck', name='吴', age=36, boss=false, birth=Fri Jan 11 00:00:00 CST 2019, maps=null, list=null, dog=null}

Person{email='www@qq.com', hello='luck', name='吴', age=12, boss=false, birth=Fri Jan 11 00:00:00 CST 2019, maps={k1=v1, k2=v2}, list=[ww, xx, rr], dog=Dog{name='cat', color='red', age=1}}

改前缀名的代码演示：

改了前缀名的结果演示：这时候读取的就是指定的配置文件的值

Person{email='www@qq.com', hello='luck', name='吴', age=12, boss=false, birth=Fri Jan 11 00:00:00 CST 2019, maps={k1=v1, k2=v2}, list=[ww, xx, rr], dog=Dog{name='cat', color='red', age=1}}

Person1{email='www', hello='luck', name='吴', age=36, boss=false, birth=Fri Jan 11 00:00:00 CST 2019, maps=null, list=null, dog=null}

Person{email='12345@qq.com', hello='springboot', name='指定读取配置文件', age=12, boss=false, birth=Wed Sep 11 00:00:00 CST 2019, maps={k2=v2, k1=v1}, list=[@Value, @PropertySource], dog=Dog{name='cat', color='red', age=1}}

注：只能读取 .properties 文件，无法读取 .yml 文件

五、@ImportResource:导入Spring配置文件

让配置文件里面的内容生效

Springboot 里没有Spring 的配置文件，我们自己编写的配置文件，也不能自动识别；

想让Spring的配置文件生效，加载进来，需使用该注解

写一个Person3 类，如图所示：

自定义一个Spring配置文件，如图所示：

在启动类上注解

测试：自定义的这个配置文件是否生效

演示结果：生效了

2019-09-11 22:15:12.247 INFO 7824 --- [ main] c.w.s.demo.DemoApplicationTests : Started DemoApplicationTests in 8.558 seconds (JVM running for 10.882)

Person{email='null', hello='null', name='null', age=0, boss=false, birth=null, maps=null, list=null, dog=null}

六、思维导图

以上为个人经验，希望能给大家一个参考，也希望大家多多支持我们。