【Spring&SpringBoot】读取变量的N种方式

参考：

SpringBoot读取配置的6种方式  https://www.bilibili.com/video/BV1hh4y1j7mC/?spm_id_from=333.337.search-card.all.click&vd_source=898d5514be58985430a49b46d5500c13

尚硅谷SpringBoot视频 P10~P13

 

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基于Spring读取配置：

1、逐个配置：@Value：支持SpEL语法，不支持JSR303校验；不支持复杂类型注解（如map）

2、指定配置文件 @PropertySource("classpath:foo.properties")  +   @Configuration annotation: // 指定多个

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 基于Spring Boot读取配置

1、默认读取：src/main/resources/application.properties  或  application.yaml

2、定义环境相关参数  application-environment.properties 

3、简化配置：@ConfigurationPeroperties(prefix="")， 批量注入文件中属性，不支持SpEL语法，JSR303校验

4、指定测试专用properties 文件：src/test/resources/

5、注解：@TestPropertySource

@RunWith(SpringRunner.class)
@TestPropertySource("/foo.properties")
public class FilePropertyInjectionUnitTest {

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

    @Test
    public void whenFilePropertyProvided_thenProperlyInjected() {
        assertThat(foo).isEqualTo("bar");
    }
}

配置随机值：If we don't want determinist property values, we can use RandomValuePropertySource to randomize the values of properties:

random.number=${random.int}
random.long=${random.long}
random.uuid=${random.uuid}

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其他（不推荐）

PropertySourcesPlaceholderConfigurer ：gives us full control over the configuration, with the downside of being more verbose and most of the time, unnecessary.

@Bean
public static PropertySourcesPlaceholderConfigurer properties(){
    PropertySourcesPlaceholderConfigurer pspc
      = new PropertySourcesPlaceholderConfigurer();
    Resource[] resources = new ClassPathResource[ ]
      { new ClassPathResource( "foo.properties" ) };
    pspc.setLocations( resources );
    pspc.setIgnoreUnresolvablePlaceholders( true );
    return pspc;
}

 

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Spring场景：Register a Properties File via Annotations

@Configuration
@PropertySource("classpath:foo.properties")
public class PropertiesWithJavaConfig {
    //...
}

定义多个

@PropertySource("classpath:foo.properties")
@PropertySource("classpath:bar.properties")
public class PropertiesWithJavaConfig {
    //...
}

或

@PropertySources({
    @PropertySource("classpath:foo.properties"),
    @PropertySource("classpath:bar.properties")
})
public class PropertiesWithJavaConfig {
    //...
}

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 Spring：注入参数 @Value

补充：取不到值：设置默认值，@Value("${Person.address:CCC}") 

Validate JSR 303的使用：会提示lastName格式报错

 参数类型不匹配，启动报错

 

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 SpringBoot：@ConfigurationPeroperties(prefix="")

application.yaml配置如下：

person：
    lastName: hello
    age: 18
    boss: false
    birth: 2017/12/12
    maps:{k1: v1, k2: 12}
    lists:
        - lisi
        - zhaoliu
    dog:
        name: 小狗
        age： 12

代码

/**
* 将配置文件中配置的每个属性的值，映射到这个组件中
* @ConfigurationProperties 告诉 SpringBoot将本类中所有属性和配置文件中相关配置绑定
* prefix = "person" 配置文件中哪个下面的所有属性一一映射
*/

@Component
@ConfigurationPeroperties(prefix = "person")
public class Person {
　　private String lastName;
　　private Integer age;
　　private Boolean boss;
　　private Date birth;

　　private Map<String ,Object> maps;
      private List<Object> lists;
      private Dog dog;
     ....
}

public class Dog{
      private String name;
      private Integer age;
}

 Pom.xml增加依赖

<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-configuration-processor</artifactId>
   <optional>true</optional>
</dependency>

<!--  Spring Test 插件-->
<dependency>
   <groupId>org.springframework.boot</groupId>
   <artifactId>spring-boot-starter-test</artifactId>
   <scope>test</scope>
</dependency>

配置spring test类，验证效果

 

使用application.properties（先将原有yaml文件中使用#注释，可直接用快捷键 Ctrl+/实现快速屏蔽）

Person.last-name=lisi
Person.age=18
Person.boss=false
Person.birth=2019/12/12
Person.maps.k1=v1
Person.maps.k2=14
Person.lists=a,b,c

重新Test执行效果：

说明：如果配置文件中配置中文打印乱码，则是工程字符集问题（Properties文件模式GBK编码，需调整UTF-8），参考如下调整。

 

 修正后的打印效果：