java Spring YML数组属性为空

Question

我试图从application.yml读取字符串数组，但徒劳。 Environment和@Value注释始终返回null

如果我读取一个项目，而不是整个数组，那么一切都会正常工作

代码如下：

来源

---

启动应用程序和Rest控制器

import java.util.List;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Value;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.core.env.Environment;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

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

@RestController
class WithEnvCtrl {

    @Autowired
    private Environment env;

    @RequestMapping(value = "/with_env", method = { RequestMethod.GET, RequestMethod.POST }, produces = "application/json")
    public String test() {

        System.err.println(env.getProperty("this.is.array[0]"));
        System.err.println(env.getProperty("this.is.array", List.class));
        System.err.println(env.getProperty("this.is.array", String[].class));

        return env.getProperty("this.is.array[0]");
    }
}

@RestController
class WithValueAnnotation {

    @Value("${this.is.array[0]}")
    private String first;

    @Value("${this.is.array}")
    private List<String> list;

    @Value("${this.is.array}")
    private String[] array;

    @RequestMapping(value = "/with_value_annotation", method = { RequestMethod.GET, RequestMethod.POST }, produces = "application/json")
    public String test() {

        System.err.println(first);
        System.err.println(list);
        System.err.println(array);

        return first;
    }
}

应用程序。yml文件

this:
  is:
    array: 
      - "casa"
      - "pesenna"

结果

---

WithEnvCtrl.test方法打印：

casa
null
null
null

WithValueAnnotation.test方法使用数组的第一个元素（casa）正确设置变量first。但是，属性list和array上的注释@Value会导致异常：

java.lang.IllegalArgumentException: Could not resolve placeholder 'this.is.array' in string value "${this.is.array}"

下面是一个示例项目：property-array

非常感谢

Answer 1

解决者：

• 使用注释@ConfigurationProperties
• 声明与yml属性同名的属性
• 定义属性的get方法
• 初始化属性或定义set方法

---

代码如下：

import java.util.List;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RestController;

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

@RestController
@ConfigurationProperties(prefix="this.is")
class WithValueAnnotation {

    private List<String> array;

    public List<String> getArray(){
        return this.array;
    }

    public void setArray(List<String> array){
        this.array = array;
    }

    @RequestMapping(value = "/test_cfg", method = { RequestMethod.GET,
            RequestMethod.POST }, produces = "application/json")
    public String test() {

        System.err.println(array);

        return array.toString();
    }
}

谢谢@Quagaar