java 静态函数中@Value 注释的替代方法
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An alternative to @Value annotation in static function
提问by Sanghyun Lee
It's not possible to use @Valueon a static variable.
不能@Value在静态变量上使用。
@Value("${some.value}")
static private int someValue;
static public void useValue() {
System.out.println(someValue);
}
When I do this, 0is printed. So what is a good alternative to this?
当我这样做时，0打印出来。那么有什么好的替代方法呢？
回答by Ralph
Spring inject noting in static field (by default).
Spring 在静态字段中注入注释（默认情况下）。
So you have two alternatives:
所以你有两种选择：
- (the better one) make the field non static
- (the ugly hack) add an none static setter which writes in the static field, and add the
@Valueannotation to the setter.
- （更好的）使字段非静态
- （丑陋的黑客）添加一个写入静态字段的非静态 setter，并将
@Value注释添加到 setter。
- and then there is the trick with the MethodInvokingFactoryBean-- this example is for autowired fiels, but I guess you can adapt it for
@Valuetoo
- 再有就是用的MethodInvokingFactoryBean绝招-这个例子是自动装配Autowired fiels，但我猜你能适应它
@Value太
回答by membersound
Use this simple trick to achieve what you want (way better than having the value injected into non-static setters and writing so a static field - as suggested in the accepted answer):
使用这个简单的技巧来实现你想要的（比将值注入非静态 setter 并编写静态字段更好 - 正如接受的答案中所建议的那样）：
@Service
public class ConfigUtil {
public static ConfigUtil INSTANCE;
@Value("${some.value})
private String value;
@PostConstruct
public void init() {
INSTANCE = this;
}
public String getValue() {
return value;
}
}
Use like:
像这样使用：
ConfigUtil.INSTANCE.getValue();
ConfigUtil.INSTANCE.getValue();
回答by Florian Sager
To prevent ever repeating injections of the same value making a field non-staticin a class that gets instantiated very often, I preferred to create a simple Singleton ConfigUtil as a workaround:
为了防止重复注入相同的值使经常实例化的类中的字段变得非静态，我更喜欢创建一个简单的 Singleton ConfigUtil 作为解决方法：
package de.agitos.app.util;
import org.springframework.beans.factory.annotation.Configurable;
import org.springframework.beans.factory.annotation.Value;
/**
* Helper class to get injected configuration values from static methods
*
* @author Florian Sager
*
*/
@Configurable
public class ConfigUtil {
private static ConfigUtil instance = new ConfigUtil();
public static ConfigUtil getInstance() {
return instance;
}
private @Value("${my.value1}") Integer value1;
public Integer getValue1() {
return value1;
}
}
Inside the class I tried to inject the value first as a static Integer:
在类中，我尝试首先将值作为静态整数注入：
private static Integer value1 = ConfigUtil.getInstance().getValue1();
