配置中心入門案例以及出現Could not resolve placeholder 'XXX' in value "${XXX}"的解決方式

編寫配置中心的服務端

建立項目

修改 pom 文件添加 config-server 座標

<?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>2.1.11.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.bjsxt</groupId>
    <artifactId>config-server</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>config-server</name>
    <description>config-server</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR4</spring-cloud.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-config-server</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</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>

</project>

修改配置文件添加 Git 地址（將配置文件上傳到gitee上）

spring.application.name=yxf-config-server server.port=9010 eureka.client.service-url.defaultZone=http://admin:1234@192.168.41.242:5050/eureka/,http://admin:1234@192.168.41.242:5051/eureka/
 #Git配置 spring.cloud.config.server.git.uri=https://gitee.com/sakurayxf/config
#spring.cloud.config.server.git.username= #spring.cloud.config.server.git.password=

修改啓動類

package com.bjsxt; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.config.server.EnableConfigServer; import org.springframework.cloud.netflix.eureka.EnableEurekaClient; @SpringBootApplication @EnableEurekaClient @EnableConfigServer public class ConfigServerApplication { public static void main(String[] args) { SpringApplication.run(ConfigServerApplication.class, args); } }

建立四個臨時配置文件

注意命令規則html

經過配置中心訪問配置文件

編寫配置中心的客戶端

修改 pom 文件添加配置中心客戶端座標

<?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>2.1.11.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.bjsxt</groupId>
    <artifactId>config-client</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>config-client</name>
    <description>config-client</description>

    <properties>
        <java.version>1.8</java.version>
        <spring-cloud.version>Greenwich.SR4</spring-cloud.version>
    </properties>

    <dependencies>
        <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.cloud</groupId>
            <artifactId>spring-cloud-starter-netflix-eureka-client</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>

</project>

修改啓動類

package com.bjsxt; import org.springframework.boot.SpringApplication; import org.springframework.boot.autoconfigure.SpringBootApplication; import org.springframework.cloud.netflix.eureka.EnableEurekaClient; import org.springframework.context.annotation.Bean; import org.springframework.context.support.PropertySourcesPlaceholderConfigurer; @SpringBootApplication @EnableEurekaClient public class ConfigClientApplication { public static void main(String[] args) { SpringApplication.run(ConfigClientApplication.class, args); } }

修改配置文件

修改配置文件的名稱。客戶端配置文件名稱必須爲 bootstrap.properties

spring.application.name=config-client server.port=9011 eureka.client.service-url.defaultZone=http://admin:1234@192.168.41.242:5050/eureka/,http://admin:1234@192.168.41.242:5051/eureka/
 #默認 false,這裏設置 true,表示開啓讀取配置中心的配置 spring.cloud.config.discovery.enabled=true #對應 eureka 中的配置中心 serviceId，默認是 configserver spring.cloud.config.discovery.service-id=yxf-config-server #指定環境 spring.cloud.config.profile=dev #git 標籤 spring.cloud.config.label=master

編寫測試代碼

package com.bjsxt.controller; import org.springframework.beans.factory.annotation.Value; import org.springframework.web.bind.annotation.RequestMapping; import org.springframework.web.bind.annotation.RestController; @RestController public class ShowController { @Value("${e-book}") private String msg; @RequestMapping("/msg") public String Msg(){ return msg; } }

在寫這個的過程當中，實驗了好幾回都會出現這樣的問題java

度娘也說了幾種解決方法：git

1.就是配置文件必須是bootstrap.properties/ymlweb

2.就是spring

去找註冊中心中的服務必須名稱正確。apache

3.就是我遇到的這種，bootstrap

客戶端的名稱必須是config-client，不會就讀取不到值。app

總之這個問題花費了我很長時間，最後仍是老師過來幫我解決的，問題也是不容易發現。maven

原文出處：https://www.cnblogs.com/sakura-yxf/p/12037074.htmlspring-boot