Spring Boot读取properties配置文件中的数据

Java EE 目录：https://blog.csdn.net/dkbnull/article/details/

Spring Boot 专栏：https://blog.csdn.net/dkbnull/category_9278145.html

Spring Cloud 专栏：https://blog.csdn.net/dkbnull/category_9287932.html

Spring Boot最常用的3种读取properties配置文件中数据的方法：

1、使用@Value注解读取

读取properties配置文件时，默认读取的是application.properties。

application.properties：

demo.name=Name demo.age=18

Java代码：

import org.springframework.beans.factory.annotation.Value; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @RestController public class GatewayController { @Value("${demo.name}") private String name; @Value("${demo.age}") private String age; @RequestMapping(value = "/gateway") public String gateway() { return "get properties value by ''@Value'' :" + //1、使用@Value注解读取 " name=" + name + " , age=" + age; } }

运行结果如下：

这里，如果要把

 @Value(“${demo.name}”)
            

private String name;
            

@Value(“${demo.age}”)
            

private String age;

部分放到一个单独的类A中进行读取，然后在类B中调用，则要把类A增加@Component注解，并在类B中使用@Autowired自动装配类A，代码如下。

类A：

import org.springframework.beans.factory.annotation.Value; import org.springframework.stereotype.Component; @Component public class ConfigBeanValue { @Value("${demo.name}") public String name; @Value("${demo.age}") public String age; }

类B：

import cn.wbnull.springbootdemo.config.ConfigBeanValue; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @RestController public class GatewayController { @Autowired private ConfigBeanValue configBeanValue; @RequestMapping(value = "/gateway") public String gateway() { return "get properties value by ''@Value'' :" + //1、使用@Value注解读取 " name=" + configBeanValue.name + " , age=" + configBeanValue.age; } } 

运行结果如下：

注意：如果@Value${}所包含的键名在application.properties配置文件中不存在的话，会抛出异常：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name ‘configBeanValue’: Injection of autowired dependencies failed; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder ‘demo.name’ in value “${demo.name}”

2、使用Environment读取

application.properties：

demo.sex=男 demo.address=山东 

Java代码：

import cn.wbnull.springbootdemo.config.ConfigBeanValue; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.core.env.Environment; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @RestController public class GatewayController { @Autowired private ConfigBeanValue configBeanValue; @Autowired private Environment environment; @RequestMapping(value = "/gateway") public String gateway() { return "get properties value by ''@Value'' :" + //1、使用@Value注解读取 " name=" + configBeanValue.name + " , age=" + configBeanValue.age + "
get properties value by ''Environment'' :" + //2、使用Environment读取 " , sex=" + environment.getProperty("demo.sex") + " , address=" + environment.getProperty("demo.address"); } } 

运行，发现中文乱码：

这里，我们在application.properties做如下配置：

server.tomcat.uri-encoding=UTF-8 spring.http.encoding.charset=UTF-8 spring.http.encoding.enabled=true spring.http.encoding.force=true spring.messages.encoding=UTF-8 

然后修改IntelliJ IDEA，File –> Settings –> Editor –> File Encodings ，将最下方Default encoding for properties files设置为UTF-8，并勾选Transparent native-to-ascii conversion。

重新运行结果如下：

3、使用@ConfigurationProperties注解读取

在实际项目中，当项目需要注入的变量值很多时，上述所述的两种方法工作量会变得比较大，这时候我们通常使用基于类型安全的配置方式，将properties属性和一个Bean关联在一起，即使用注解@ConfigurationProperties读取配置文件数据。

在src\main\resources下新建config.properties配置文件：

demo.phone=10086 demo.wife=self 

创建ConfigBeanProp并注入config.properties中的值：

import org.springframework.boot.context.properties.ConfigurationProperties; import org.springframework.context.annotation.PropertySource; import org.springframework.stereotype.Component; @Component @ConfigurationProperties(prefix = "demo") @PropertySource(value = "config.properties") public class ConfigBeanProp { private String phone; private String wife; public String getPhone() { return phone; } public void setPhone(String phone) { this.phone = phone; } public String getWife() { return wife; } public void setWife(String wife) { this.wife = wife; } } 

@Component 表示将该类标识为Bean

@ConfigurationProperties(prefix = “demo”)用于绑定属性，其中prefix表示所绑定的属性的前缀。

@PropertySource(value = “config.properties”)表示配置文件路径。

使用时，先使用@Autowired自动装载ConfigBeanProp，然后再进行取值，示例如下：

import cn.wbnull.springbootdemo.config.ConfigBeanProp; import cn.wbnull.springbootdemo.config.ConfigBeanValue; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.core.env.Environment; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @RestController public class GatewayController { @Autowired private ConfigBeanValue configBeanValue; @Autowired private Environment environment; @Autowired private ConfigBeanProp configBeanProp; @RequestMapping(value = "/gateway") public String gateway() { return "get properties value by ''@Value'' :" + //1、使用@Value注解读取 " name=" + configBeanValue.name + " , age=" + configBeanValue.age + "
get properties value by ''Environment'' :" + //2、使用Environment读取 " sex=" + environment.getProperty("demo.sex") + " , address=" + environment.getProperty("demo.address") + "
get properties value by ''@ConfigurationProperties'' :" + //3、使用@ConfigurationProperties注解读取 " phone=" + configBeanProp.getPhone() + " , wife=" + configBeanProp.getWife(); } } 

运行结果如下：

GitHub：https://github.com/dkbnull/SpringBootDemo

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