SpringCloudConfig之client端报错Could not resolve placeholder ‘from‘ in value “${from}“

古城微笑少年丶 2023-06-01 06:17 10阅读 0赞

### 一、前言 ###

环境：jdk 1.8，SpringCloud Greenwich.SR2。

如题，springcloud config-client启动报错：**Could not resolve placeholder 'from' in value "$\{from\}"**，具体异常堆栈如下：

Error starting ApplicationContext. To display the conditions report re-run your application with 'debug' enabled.
    2019-10-02 11:33:10.394 ERROR 9204 --- [           main] o.s.boot.SpringApplication               : Application run failed
    
    org.springframework.beans.factory.BeanCreationException: 
        Error creating bean with name 'scopedTarget.testController': 
        Injection of autowired dependencies failed; 
        nested exception is java.lang.IllegalArgumentException: 
        Could not resolve placeholder 'from' in value "${from}"
            at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessProperties(AutowiredAnnotationBeanPostProcessor.java:380) ~[spring-beans-5.1.5.RELEASE.jar:5.1.5.RELEASE]
            ..
    Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'from' in value "${from}"
        ..

### 二、排查 ###

很显然，无法成功启动SpringCloudConfig客户端的原因是不能从配置文件中解析并成功注入属性值*$\{from\}*。

回头检查SpringCloudConfig服务端的配置和运行状况均正常无误，再查看上面异常之前的启动日志，也显示了可以成功连接到config-server，如下：

2019-10-02 11:33:06.919  INFO 9204 --- [           main] c.c.c.ConfigServicePropertySourceLocator : Fetching config from server at : http://localhost:7001/
    2019-10-02 11:33:08.789  INFO 9204 --- [           main] c.c.c.ConfigServicePropertySourceLocator : Located environment: name=spring-cloud-config-client, profiles=[dev], label=master, version=516591f9604c28b12cd5a65f9fb89806f2f1c602, state=null
    2019-10-02 11:33:08.789  INFO 9204 --- [           main] b.c.PropertySourceBootstrapConfiguration : Located property source: CompositePropertySource {name='configService', propertySources=[MapPropertySource {name='configClient'}]}

所以只可能是config-client自身的问题，它的***bootstrap.properties***配置如下：

![20191002223528370.png][]

其中，testcloud为config-server中配置的Git仓库中存储的配置文件名中的$\{application\}部分。

### 三、调试 ###

config-client要从config-server通过http的方式获取到对应分支和对应环境的testcloud配置属性，即[http://localhost:7001/testcloud/dev/master/][http_localhost_7001_testcloud_dev_master]，因此在ConfigServicePropertySourceLocator中，打断点看看具体是怎么获取的。

![watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3Nvbmd6ZWhhbw_size_16_color_FFFFFF_t_70][]

查看http请求参数args的值，期待参数**/\{name\}/\{profile\}/\{label\}**中的name=testcloud，而非**spring.cloud.config.name**的值spring-cloud-config-client，因此要么删掉属性spring.cloud.config.name，使第一个参数为spring.application.name=testcloud；要么将其直接设置为testcloud即可。下面列出正确的配置：

#对应config-server中配置文件的{application}部分
    spring.application.name=testcloud
    server.port=7002
    
    #注意此属性将覆盖spring.application.name，若不一致则会导致不能从config-server读取PropertySources
    spring.cloud.config.name=testcloud
    #对应config-server中配置文件的{profile}部分
    spring.cloud.config.profile=dev
    #对应config-server中配置文件的{label}部分
    spring.cloud.config.label=master
    #配置中心config-server的地址
    spring.cloud.config.uri=http://localhost:7001/

### 四、测试 ###

测试Controller类如下：

@RefreshScope
    @RestController
    public class TestController {
        @Value("${from}")
        private String from;
        @Autowired
        private Environment env;
    
        @RequestMapping("/from")
        public String fetchFromVal() {
            return from;
        }
    
        @RequestMapping("/from2")
        public String fetchFromVal2() {
            return env.getProperty("from", "undefined");
        }
    }

浏览器或Postman或curl访问[http://localhost:7002/from][http_localhost_7002_from]和[http://localhost:7002/from2][http_localhost_7002_from]，均可成功获取到属性值，如下：

![20191002230634108.png][]

[20191002223528370.png]: /images/20230601/6cd275e546144f8c91d20951ec62836b.png
[http_localhost_7001_testcloud_dev_master]: http://localhost:7001/
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3Nvbmd6ZWhhbw_size_16_color_FFFFFF_t_70]: /images/20230601/49a94ef14b5944b49306fdc11506f6b5.png
[http_localhost_7002_from]: http://localhost:7002/from
[20191002230634108.png]: /images/20230601/eca3b2bb431a4dd5ad59e79a591fd269.png