Spring - using static final fields (constants) for bean initialization

lisak picture lisak · May 24, 2010 · Viewed 82.6k times · Source

is it possible to define a bean with the use of static final fields of CoreProtocolPNames class like this:


<bean id="httpParamBean" class="org.apache.http.params.HttpProtocolParamBean">
     <constructor-arg ref="httpParams"/>
     <property name="httpElementCharset" value="CoreProtocolPNames.HTTP_ELEMENT_CHARSET" />
     <property name="version" value="CoreProtocolPNames.PROTOCOL_VERSION">
</bean>

public interface CoreProtocolPNames {

    public static final String PROTOCOL_VERSION = "http.protocol.version"; 

    public static final String HTTP_ELEMENT_CHARSET = "http.protocol.element-charset"; 
}

If it is possible, what is the best way of doing this ?

Answer

Paul McKenzie picture Paul McKenzie · May 24, 2010

Something like this (Spring 2.5)

<bean id="foo" class="Bar">
    <property name="myValue">
        <util:constant static-field="java.lang.Integer.MAX_VALUE"/>
    </property>
</bean>

Where util namespace is from xmlns:util="http://www.springframework.org/schema/util"

But for Spring 3, it would be cleaner to use the @Value annotation and the expression language. Which looks like this:

public class Bar {
    @Value("T(java.lang.Integer).MAX_VALUE")
    private Integer myValue;
}