Spring Boot：使用@Value或@ConfigurationProperties从yaml读取列表 [英] Spring Boot: read list from yaml using @Value or @ConfigurationProperties

问题描述

我想从yaml文件（application.yml）中读取主机列表，文件如下所示：

I want to read a list of hosts from a yaml file (application.yml), the file looks like this:

cors:
    hosts:
        allow: 
            - http://foo1/
            - http://foo2/
            - http://foo3/

（示例1）

值如下：

@Value("${cors.hosts.allow}")   
List<String> allowedHosts;

但是阅读失败，因为Spring抱怨说：

But reading fails as Spring complains about this:

java.lang.IllegalArgumentException：无法在字符串值$ {cors.hosts.allow}中解析占位符
'cors.hosts.allow'

java.lang.IllegalArgumentException: Could not resolve placeholder 'cors.hosts.allow' in string value "${cors.hosts.allow}"

当我这样更改文件时，属性可以被读取，但自然不包含列表，只有一个条目：

When I change the file like this the property can be read but naturally it does not contain the list but only one entry:

cors:
    hosts:
        allow: http://foo1, http://foo2, http://foo3

（我知道我可以读取这些值为一行，并用 ，，但我不想要一个解决方法）

(I know that I could read the values as a single line and split them by "," but I do not want to go for a workaround yet)

这不工作（虽然我认为这应该是有效的到 snakeyamls文档）：

This does not work either (although I think this should be valid according to snakeyamls docs):

cors:
    hosts:
        allow: !!seq [ "http://foo1", "http://foo2" ] 

（跳过 !! seq ，只需使用

(Skipping the !!seq and just using the [ / ] is a failure too)

我阅读建议

I read the suggestion here which involves using @ConfigurationProperties and transferred the example to Java and used it with the yaml file you see in Example1:

@Configuration
@EnableWebMvc
@ConfigurationProperties(prefix = "cors.hosts")
public class CorsConfiguration extends WebMvcConfigurerAdapter {
    @NotNull
    public List<String> allow;
...

当我执行此操作时，我收到此投诉：

When I run this I get this complaint:

org.springframework.validation.BindException：
org.springframework.boot.bind.RelaxedDataBinder $ RelaxedBeanPropertyBindingResult：
1错误对象'cors.hosts'在字段'allow'：rejected
value [null]; codes [NotNull.cors.hosts.allow，NotNull.allow，NotNull];
arguments
[org.springframework.context.support.DefaultMessageSourceResolvable：
codes [cors.hosts.allow，allow]; argumen ts [];默认消息
[允许]];

org.springframework.validation.BindException: org.springframework.boot.bind.RelaxedDataBinder$RelaxedBeanPropertyBindingResult: 1 errors Field error in object 'cors.hosts' on field 'allow': rejected value [null]; codes [NotNull.cors.hosts.allow,NotNull.allow,NotNull]; arguments [org.springframework.context.support.DefaultMessageSourceResolvable: codes [cors.hosts.allow,allow]; argumen ts []; default message [allow]];

我搜索其他方法让我的CORS主机配置， href =https://github.com/spring-projects/spring-boot/issues/3052> Spring启动问题，但因为这还没有完成，我不能使用它作为一个解决方案。
所有这一切都是使用Spring Boot 1.3 RC1

I searched for other means to have my CORS hosts configurable and found this Spring Boot issue but as this is not yet finished I can't use it as a solution. All of this is done with Spring Boot 1.3 RC1

推荐答案

这很容易，答案在这 doc 以及这一个

It's easy, the answer is in this doc and also in this one

所以，你有一个这样的yaml：

So, you have a yaml like this:

cors:
    hosts:
        allow: 
            - http://foo1/
            - http://foo2/
            - http://foo3/

/ p>

Then you first bind the data

import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;
import org.springframework.stereotype.Component;

import java.util.List;

@Component
@ConfigurationProperties(prefix="cors.hosts")
public class AllowedHosts {
    private List<String> HostNames; //You can also bind more type-safe objects
}

只是做

@Autowired
private AllowedHosts allowedHosts;

完成了！

这篇关于Spring Boot：使用@Value或@ConfigurationProperties从yaml读取列表的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！