在运行时根据输入从属性文件中获取值 - java Spring
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Get the values from the properties file at runtime based on the input - java Spring
提问by pinky
I have my colour.roperties file as
我有我的 colour.rperties 文件
rose = red
lily = white
jasmine = pink
I need to get the value for colour as
我需要获得颜色的价值
String flower = runTimeFlower;
@Value("${flower}) String colour;
where flower value we will get at runtime. How can I do this in java Spring. I need to get a single value (from among 50 values defined in the properties file )at runtime based on the user input. If i cannot use @Value , Could you tell me other ways to handle this please?
我们将在运行时获得的花值。我怎样才能在 java Spring 中做到这一点。我需要在运行时根据用户输入获取一个值（从属性文件中定义的 50 个值中）。如果我不能使用 @Value ，你能告诉我其他处理方法吗？
回答by SergeyB
There is no way to do what you are describing using @Value, but you can do this, which is the same thing pretty much:
没有办法使用@Value 来做你所描述的事情，但你可以这样做，这几乎是一样的：
package com.acme.example;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.env.Environment;
import org.springframework.stereotype.Component;
@Component
public class Example {
private @Autowired Environment environment;
public String getFlowerColor(String runTimeFlower) {
return environment.resolvePlaceholders("${" + runTimeFlower + "}");
}
}
回答by Emerson Farrugia
The PropertySources which Spring reads from won't know the value of the flowervariable, so @Valuewon't work.
PropertySourceSpring 读取的s 不知道flower变量的值，所以@Value不会工作。
Inject a Propertiesobject or a Map. Then just look up the colour using the property name or key, respectively, e.g.
注入一个Properties对象或一个Map. 然后分别使用属性名称或键查找颜色，例如
<util:properties id="appProperties" location="classpath:app.properties" />
...
@Autowired
@Qualifier("appProperties")
private Properties appProperties;
...
appProperties.getProperty(flower);
回答by Boyan
What @ike_love says it correct, but why don't you just load the properties in memory on app start and then you can resolve your flower taking value from a map? In my mind you don't need to delegate every simple thing like this to Spring. Anyway I don't know your Spring config, but in order Spring to be able to load the properties you need to define a PropertyPlaceholderConfigurer to tell where are the property files:
@ike_love 说的是对的，但为什么不在应用程序启动时加载内存中的属性，然后您可以解决从地图中获取值的花？在我看来，您不需要将像这样的每件简单事情都委托给 Spring。无论如何，我不知道您的 Spring 配置，但是为了 Spring 能够加载属性，您需要定义一个 PropertyPlaceholderConfigurer 来告诉属性文件在哪里：
<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:app.properties</value>
</list>
</property>
</bean>
