Spring系列之——springboot解析resources.application.properties文件 _spring系列

亦余心之所善兮，虽九死其犹未悔。这篇文章主要讲述Spring系列之——springboot解析resources.application.properties文件相关的知识，希望能为你提供帮助。
本文通过讲解如何解析application.properties属性，介绍了几个注解的运用@Value @ConfigurationProperties @EnableConfigurationProperties @Autowired @ConditionalOnProperty摘要：本文通过讲解如何解析application.properties属性，介绍了几个注解的运用@Value @ConfigurationProperties @EnableConfigurationProperties @Autowired @ConditionalOnProperty

1 准备
1.1 搭建springboot
1.2 写一个controller类

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package com.gbm.controller; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.ResponseBody; /** * Created by Administrator on 2019/2/20. */@Controller public class IndexController { @RequestMapping("/index") @ResponseBody public String index() { return "我爱北京天安门！"; } }

View Code2 几种获取属性值方式
配置application.properties

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value.local.province=Zhejiang value.local.city=Hangzhoucomplex.other.province=Jiangsu complex.other.city=Suzhou complex.other.flag=false

View Code2.1 使用注解@Value("${xxx}")获取指定属性值
2.1.1 在controller类中获取属性值

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package com.gbm.controller; import org.springframework.beans.factory.annotation.Value; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.ResponseBody; /** * Created by Administrator on 2019/2/20. */@Controller public class IndexController { @Value("${value.local.province}") private String province; @Value("${value.local.city}") private String city; @RequestMapping("/index") @ResponseBody public String index() { StringBuffer sb = new StringBuffer(); sb.append(this.city); sb.append(","); sb.append(this.province); sb.append(" "); return sb.toString(); } }

View Code 2.1.2 任何浏览器上运行 http://localhost:8080/index，结果如下

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2.2 使用注解@ConfigurationProperties(prefix = "xxx")获得前缀相同的一组属性，并转换成bean对象
2.2.1 写一个实体类

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package com.gbm.models; import org.springframework.boot.context.properties.ConfigurationProperties; import org.springframework.stereotype.Component; /** * Created by Administrator on 2019/2/21. */ @Component @ConfigurationProperties(prefix = "complex.other") public class Complex { private String province; private String city; private Boolean flag; public String getProvince() { return province; }public void setProvince(String province) { this.province = province; }public String getCity() { return city; }public void setCity(String city) { this.city = city; }public Boolean getFlag() { return flag; }public void setFlag(Boolean flag) { this.flag = flag; }@Override public String toString() { return "Complex{" + "province=\'" + province + \'\\\'\' + ", city=\'" + city + \'\\\'\' + ", flag=" + flag + \'}\'; } }

View Code 2.2.2 在controller类中获取属性值

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package com.gbm.controller; import com.gbm.models.Complex; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.stereotype.Controller; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.ResponseBody; /** * Created by Administrator on 2019/2/20. */@Controller public class IndexController { @Autowired private Complex complex; @RequestMapping("/index") @ResponseBody public String index() { return complex.toString(); } }

View Code 2.2.3 在SpringBootApplication中使Configuration生效

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package com.gbm.myspingboot; import com.gbm.models.Complex; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty; import org.springframework.boot.context.properties.EnableConfigurationProperties; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.ComponentScans; @SpringBootApplication @ComponentScans({@ComponentScan("com.gbm.controller"), @ComponentScan("com.gbm.models")}) @EnableConfigurationProperties(Complex.class) @ConditionalOnProperty(value = "https://www.songbingjia.com/android/complex.other.town", matchIfMissing = true) public class MyspingbootApplication {public static void main(String[] args) { SpringApplication.run(MyspingbootApplication.class, args); } }

View Code 2.2.4 任何浏览器上运行 http://localhost:8080/index，结果如下

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3 总结
关于解析application.properties文件，最重要的是对注解的使用，本文主要涉及到如下几个注解的运用
@Value("${xxx}")——获取指定属性值
@ConfigurationProperties(prefix = "xxx")——获得前缀相同的一组属性，并转换成bean对象
@EnableConfigurationProperties(xxx.class)——使Configuration生效，并从IOC容器中获取bean
@Autowired——自动注入set和get方法
@ConditionalOnProperty(value = "https://www.songbingjia.com/android/complex.other.town", matchIfMissing = true)——缺少该property时是否可以加载，如果是true，没有该property也会正常加载；如果是false则会抛出异常。例如

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package com.gbm.myspingboot; import com.gbm.models.Complex; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.boot.autoconfigure.condition.ConditionalOnProperty; import org.springframework.boot.context.properties.EnableConfigurationProperties; import org.springframework.context.annotation.ComponentScan; import org.springframework.context.annotation.ComponentScans; @SpringBootApplication @ComponentScans({@ComponentScan("com.gbm.controller"), @ComponentScan("com.gbm.models")}) @EnableConfigurationProperties(Complex.class) @ConditionalOnProperty(value = "https://www.songbingjia.com/android/complex.other.town", matchIfMissing = false) public class MyspingbootApplication {public static void main(String[] args) { SpringApplication.run(MyspingbootApplication.class, args); } }

matchIfMissing=false代码

Error starting ApplicationContext. To display the conditions report re-run your application with \'debug\' enabled. 2019-02-21 23:30:56.532 ERROR 3152 --- [main] o.s.boot.SpringApplication: Application run failed