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=Namedemo.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;@RestControllerpublic 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：

importorg.springframework.beans.factory.annotation.Value;import org.springframework.stereotype.Component;@Componentpublic 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;@RestControllerpublic 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 creatingbean with name 'configBeanValue': Injection of autowired dependencies failed;nested exception is java.lang.IllegalArgumentException: Could not resolveplaceholder '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;@RestControllerpublic 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 + "<p>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-8spring.http.encoding.charset=UTF-8spring.http.encoding.enabled=truespring.http.encoding.force=truespring.messages.encoding=UTF-8

然后修改IntelliJ IDEA，File -->Settings --> Editor --> File Encodings ，将最下方Default encodingfor properties files设置为UTF-8，并勾选Transparentnative-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srcmainresources下新建config.properties配置文件：

demo.phone=10086demo.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;@RestControllerpublic 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 + "<p>get properties value by ''Environment'' :" + //2、使用Environment读取 " sex=" + environment.getProperty("demo.sex") + " , address=" + environment.getProperty("demo.address") + "<p>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：

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

CSDN：https://blog.csdn.net/dkbnull/article/details/81953190

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本篇文章来源于微信公众号: 程序员null