Spring - 从application.properties动态创建Bean [英] Spring - Dynamically Creating Beans from application.properties

问题描述

我需要使用属性文件创建多个同名的bean。例如：

I have a need to create multiple beans of the same name using properties file. For example:

rabbit.example.language[0]=java
rabbit.example.framework[0]=spring
rabbit.example.language[1]=python
rabbit.example.framework[1]=django

我想为每个示例索引创建一个Bean（这最终将用于Rabbit Queues，但我正在简化）。这是我到目前为止正在使用的一些代码。

I'd like to create a Bean for each example index (this will ultimately be used for Rabbit Queues, but I'm simplifying things). Here's some code I'm working with so far.

Rabbits.java

Rabbits.java

@Configuration
@ConfigurationProperties(prefix="example")
public class Rabbits {
    private String language;
    private String framework;

    public String getLanguage() {
        return language;
    }

    public void setLanguage(String language) {
        this.language= language;
    }

    public String getFramework() {
        return framework;
    }

    public void setFramework(String framework) {
        this.framework= framework;
    }
}

Properties.java

Properties.java

@Configuration
@ConfigurationProperties(prefix = "rabbit")
public class Properties {

    @NestedConfigurationProperty
    private List<Rabbits> rabbits = new ArrayList<Rabbits>();

    public List<Rabbits> getRabbits() {
        return rabbits;
    }

    public void setRabbits(List<Rabbits> rabbits) {
        this.rabbits = rabbits;
    }

    @Bean
    RabbitFlowProcessor rabbitFlowProcessor(List<Rabbits> rabbit){
        return new RabbitFlowProcessor(rabbit);
    }

}

RabbitFlowProcessor.java：

RabbitFlowProcessor.java:

@Component
public class RabbitFlowProcessor implements BeanFactoryPostProcessor {

    private List<Rabbits> rabbits;

    public RabbitFlowProcessor(List<Rabbits> rabbits) {
        this.rabbits = rabbits;
    }

    @Override
    public void postProcessBeanFactory(ConfigurableListableBeanFactory  beanFactory) throws BeansException {
      rabbits.stream()
              .forEach(rabbit -> {
                  System.out.println(rabbit.getLanguage());
              });
    }
}

我期待输出为Java Python，但是兔子又回来了。谁能告诉我哪里出错？

I'm expecting the output to be Java Python, but the "rabbits" are coming back as null. Can anyone tell where I'm going wrong?

推荐答案

请用以下评论更新你的代码：

Please update your codes with following comments:

rabbit.example[0].language=java
rabbit.example[0].framework=spring
rabbit.example[1].language=python
rabbit.example[1].framework=django

作为示例将是一个List，因此您需要使用它添加索引。

As the example will be a List, so you need add the index with it.

@Configuration
@ConfigurationProperties(prefix = "rabbit")
public class RabbitsProperties {

    private List<Rabbits> example = new ArrayList<Rabbits>();

    public List<Rabbits> getExample() {
        return example;
    }

    public void setExample(List<Rabbits> example) {
        this.example = example;
    }
}

关于 NestedConfigurationProperty annoation，表示 ConfigurationProperties 对象中的字段应被视为嵌套类型。
此注释与实际绑定过程无关，但 spring-boot-configuration-processor 使用它作为字段未绑定的提示作为单个值。

About the NestedConfigurationProperty annoation, that indicates that a field in a ConfigurationProperties object should be treated as if it were a nested type. This annotation has no bearing on the actual binding processes, but it is used by the spring-boot-configuration-processor as a hint that a field is not bound as a single value.

public class Rabbits {
    private String language;
    private String framework;

    public String getLanguage() {
        return language;
    }

    public void setLanguage(String language) {
        this.language= language;
    }

    public String getFramework() {
        return framework;
    }

    public void setFramework(String framework) {
        this.framework= framework;
    }
}

通常，您可以将其添加为嵌套的内部类在 RabbitsProperties

typically, you can add this as a nested inner class in RabbitsProperties

然后在你的 RabbitFlowProcessor.java 中，您可以照常注入 RabbitsProperties 。

Then in your RabbitFlowProcessor.java, you can inject the RabbitsProperties as normal.

@Component
public class RabbitFlowProcessor implements BeanFactoryPostProcessor {

    @Autowired
    private RabbitsProperties rabbitsProperties; 
    ......
}

这篇关于Spring - 从application.properties动态创建Bean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！