Spring Boot @ConfigurationProperties 教程展示了如何在 Spring Boot 应用中使用@ConfigurationProperties 将属性绑定到对象。
Spring 是流行的 Java 应用框架，而 Spring Boot 是 Spring 的演进，可以帮助轻松地创建独立的，生产级的基于 Spring 的应用。
@ConfigurationProperties
@ConfigurationProperties允许轻松地将整个 Properties 和 Yaml 文件映射到一个对象。 它还允许使用 JSR-303 bean 验证来验证属性。 默认情况下，注解从application.properties文件中读取。 可以使用@PropertySource注解来更改源文件。
Spring Boot @ConfigurationProperties示例
以下应用从application.properties文件读取配置数据，该文件是默认的 Spring Boot 配置文件。
pom.xmlsrc├───main│ ├───java│ │ └───com│ │ └───zetcode│ │ │ Application.java│ │ │ MyRunner.java│ │ └───conf│ │ AppProperties.java│ └───resources│ application.properties└───test └───java
这是项目结构。
pom.xml
<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.zetcode</groupId> <artifactId>springbootconfigurationproperties</artifactId> <version>1.0-SNAPSHOT</version> <packaging>jar</packaging> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.source>11</maven.compiler.source> <maven.compiler.target>11</maven.compiler.target> </properties> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.1.RELEASE</version> </parent> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build></project>
这是 Maven pom.xml文件。
resources/application.properties
spring.main.banner-mode=offapp.colour=steelblueapp.lang=enapp.theme=dark
在application.properties文件中，我们具有三个自定义属性。 它们具有app前缀。
com/zetcode/conf/AppProperties.java
package com.zetcode.conf;import org.springframework.boot.context.properties.ConfigurationProperties;import org.springframework.context.annotation.Configuration;@Configuration@ConfigurationProperties(prefix = "app")public class AppProperties { private String colour; private String lang; private String theme; public String getColour() { return colour; } public void setColour(String colour) { this.colour = colour; } public String getLang() { return lang; } public void setLang(String lang) { this.lang = lang; } public String getTheme() { return theme; } public void setTheme(String theme) { this.theme = theme; }}这些属性将绑定到此配置对象。
@Configuration@ConfigurationProperties(prefix = "app")public class AppProperties {@Configuration注解使它成为 Spring 管理的 bean。 在@ConfigurationProperties中，我们为属性设置前缀。
com/zetcode/MyRunner.java
package com.zetcode;import com.zetcode.conf.AppProperties;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.CommandLineRunner;import org.springframework.stereotype.Component;@Componentpublic class MyRunner implements CommandLineRunner { private static final Logger logger = LoggerFactory.getLogger(Application.class); @Autowired private AppProperties appProperties; @Override public void run(String... args) throws Exception { logger.info("Colour: {}", appProperties.getColour()); logger.info("Language: {}", appProperties.getLang()); logger.info("Theme: {}", appProperties.getTheme()); }}在MyRunner中，我们将AppProperties注入字段中并读取其值。
com/zetcode/Application.java
package com.zetcode;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplicationpublic class Application { public static void main(String[] args) { SpringApplication.run(Application.class, args); }}Application是设置 Spring Boot 应用的入口。
Spring Boot @ConfigurationProperties示例 II
在第二个应用中，我们还将验证属性。
pom.xmlsrc├───main│ ├───java│ │ └───com│ │ └───zetcode│ │ │ Application.java│ │ │ MyRunner.java│ │ └───config│ │ MailProperties.java│ └───resources│ application.properties│ mail.properties└───test └───java
这是项目结构。
pom.xml
<?xml version="1.0" encoding="UTF-8"?><project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"> <modelVersion>4.0.0</modelVersion> <groupId>com.zetcode</groupId> <artifactId>springbootconfigurationpropertiesvalidation</artifactId> <version>1.0-SNAPSHOT</version> <packaging>jar</packaging> <properties> <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding> <maven.compiler.source>11</maven.compiler.source> <maven.compiler.target>11</maven.compiler.target> </properties> <parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.1.1.RELEASE</version> </parent> <dependencies> <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter</artifactId> </dependency> <dependency> <groupId>org.hibernate.validator</groupId> <artifactId>hibernate-validator</artifactId> </dependency> </dependencies> <build> <plugins> <plugin> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-maven-plugin</artifactId> </plugin> </plugins> </build></project>
这是pom.xml文件。 我们还有一个hibernate-validator依赖项。
resources/application.properties
spring.main.banner-mode=off
这是application.properties文件。
resources/mail.properties
hostname=info@example.comport=9000from=admin@example.comrecipients[0]=user1@example.comrecipients[1]=user2@example.comrecipients[2]=user3@example.comrecipients[3]=user4@example.com
我们有一个自定义的mail.properties文件。
com/zetcode/config/MailProperties.java
package com.zetcode.config;import org.springframework.boot.context.properties.ConfigurationProperties;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.PropertySource;import org.springframework.validation.annotation.Validated;import javax.validation.constraints.Max;import javax.validation.constraints.Min;import javax.validation.constraints.NotNull;import java.util.List;@Configuration@PropertySource("classpath:mail.properties")@ConfigurationProperties@Validatedpublic class MailProperties { @NotNull private String hostname; @Min(1000) @Max(10000) private int port; @NotNull private String from; @NotNull private List<String> recipients; public String getHostname() { return hostname; } public void setHostname(String hostname) { this.hostname = hostname; } public int getPort() { return port; } public void setPort(int port) { this.port = port; } public String getFrom() { return from; } public void setFrom(String from) { this.from = from; } public List<String> getRecipients() { return recipients; } public void setRecipients(List<String> recipients) { this.recipients = recipients; }}我们使用@PropertySource注解设置自定义属性文件的路径。 @Validated注解验证属性。
com/zetcode/MyRunner.java
package com.zetcode;import com.zetcode.config.MailProperties;import org.slf4j.Logger;import org.slf4j.LoggerFactory;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.CommandLineRunner;import org.springframework.stereotype.Component;@Componentpublic class MyRunner implements CommandLineRunner { private static final Logger logger = LoggerFactory.getLogger(Application.class); @Autowired private MailProperties mailProperties; @Override public void run(String... args) throws Exception { logger.info("Hostname: {}", mailProperties.getHostname()); logger.info("Port: {}", mailProperties.getPort()); logger.info("From: {}", mailProperties.getFrom()); logger.info("Recipients: {}", mailProperties.getRecipients()); }}我们注入MailProperties并以run()方法读取它们。
com/zetcode/Application.java
package com.zetcode;import org.springframework.boot.SpringApplication;import org.springframework.boot.autoconfigure.SpringBootApplication;@SpringBootApplicationpublic class Application { public static void main(String[] args) { SpringApplication.run(Application.class, args); }}这是Application类。
我们使用mvn -q spring-boot:run运行该应用。
在本教程中，我们展示了如何使用@ConfigurationProperties从外部文件读取配置属性。
