spring 配置客户端 - 启动客户端时无法解析值“${message}”中的占位符“message”错误

如何解决spring 配置客户端 - 启动客户端时无法解析值“${message}”中的占位符“message”错误

我正在实施 spring config server。我的配置服务器启动正常，我可以从位于 http://localhost:8888/client-config/development 的 URL C:\\configprop 获取数据，如下所示。

{
    "name": "client-config","profiles": [
        "development"
    ],"label": null,"version": "0dec53953ad4f620031cdbb3a99a0fe9701fb9df","state": null,"propertySources": [
        {
            "name": "C:\\\\configprop/file:C:\\Users\\{user}\\AppData\\Local\\Temp\\config-repo-5116664058083487059\\client-config-development.properties","source": {
                "msg": "Hello world - this is from config server - Development Environment"
            }
        }
    ]
}

但是当我使用 config client 获取 http://localhost:8080/message 中的数据时，我收到了 Could not resolve placeholder 'message' in value "${message}" 错误。

客户申请

主类

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class ConfigClientApplication {

    public static void main(String[] args) {
        SpringApplication.run(ConfigClientApplication.class,args);
    }
}

控制器类

package com.example.demo;

import org.springframework.beans.factory.annotation.Value;
import org.springframework.cloud.context.config.annotation.RefreshScope;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RefreshScope
@RestController
public class MessageRestController {

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

    @GetMapping("/message")
    public String getMessage() {
        return this.message;
    }
}

aplication.yml

spring:
  application:
    name: client-config
  cloud:
    config:
      uri: http://localhost:8888
  profiles:
    active: development
management:
  endpoints:
    web:
      exposure:
        include: refresh

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 https://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.4.2</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.example</groupId>
    <artifactId>config-client</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>config-client</name>
    <description>Demo project for Spring Boot</description>
    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>2020.0.0</spring-cloud.version>
    </properties>
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-actuator</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-rest</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-config</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>
    <dependencyManagement>
        <dependencies>
            <dependency>
                <groupId>org.springframework.cloud</groupId>
                <artifactId>spring-cloud-dependencies</artifactId>
                <version>${spring-cloud.version}</version>
                <type>pom</type>
                <scope>import</scope>
            </dependency>
        </dependencies>
    </dependencyManagement>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
    <repositories>
        <repository>
            <id>spring-milestones</id>
            <name>Spring Milestones</name>
            <url>https://repo.spring.io/milestone</url>
        </repository>
    </repositories>

</project>

client-config-development.properties

message = Hello world - this is from config server - Development Environment

解决方法

嘿可以通过这个注入这个属性

步骤 1 创建一个这样的类并在 ConfigurationProperties 中传递应用程序属性路径前缀

@ConfigurationProperties(prefix = "app.xyz")
@Getter
@Setter
@Configuration
public class LoginProperties {

    private String message;
    
}

在应用程序属性

@SpringBootApplication
@EnableConfigurationProperties(LoginProperties.class)
public class Application {

    public static void main(String[] args) {
        SpringApplication.run(Application.class,args);
    }
}

在您的 application.yml 属性文件中，您可能具有这种类型的值

app:
    xyz:
      message: "Hello Java"

在你的 MessageRestController 类中

@Autowired private LoginProperties loginProperties;

然后试试

 @GetMapping("/message")
    public String getMessage() {
        return loginProperties.getMessage;
    }

    

或者你可以直接尝试这种方式但不确定

@GetMapping("/message")
    public String getMessage() {
        return `${message}`;
    }

,

根据 Spring Cloud 2020.0 的 release notes，存在重大更改。

你需要在application.yml中加入以下内容

spring.config.import="configserver:"