Package org.springframework.beans.factory.config

Class PlaceholderConfigurerSupport

java.lang.Object
org.springframework.core.io.support.PropertiesLoaderSupport
org.springframework.beans.factory.config.PropertyResourceConfigurer
org.springframework.beans.factory.config.PlaceholderConfigurerSupport
All Implemented Interfaces:
Aware, BeanFactoryAware, BeanNameAware, BeanFactoryPostProcessor, Ordered, PriorityOrdered
Direct Known Subclasses:
PropertyPlaceholderConfigurer, PropertySourcesPlaceholderConfigurer
public abstract class PlaceholderConfigurerSupport extends PropertyResourceConfigurer implements BeanNameAware, BeanFactoryAware
Abstract base class for property resource configurers that resolve placeholders in bean definition property values. Implementations pull values from a properties file or other property source into bean definitions.

The default placeholder syntax follows the Ant / Log4J / JSP EL style: 

${...}
Example XML bean definition: 
 <bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">
   <property name="driverClassName" value="${driver}" />
   <property name="url" value="jdbc:${dbname}" />
 </bean>
Example properties file: 
 driver=com.mysql.jdbc.Driver
 dbname=mysql:mydb
Annotated bean definitions may take advantage of property replacement using the @Value annotation: 
@Value("${person.age}")
Implementations check simple property values, lists, maps, props, and bean names in bean references. Furthermore, placeholder values can also cross-reference other placeholders, like: 
 rootPath=myrootdir
 subPath=${rootPath}/subdir
In contrast to PropertyOverrideConfigurer, subclasses of this type allow filling in of explicit placeholders in bean definitions.

If a configurer cannot resolve a placeholder, a BeanDefinitionStoreException will be thrown. If you want to check against multiple properties files, specify multiple resources via the locations property. You can also define multiple configurers, each with its own placeholder syntax. Use ignoreUnresolvablePlaceholders to intentionally suppress throwing an exception if a placeholder cannot be resolved.

Default property values can be defined globally for each configurer instance via the properties property, or on a property-by-property basis using the value separator which is ":" by default and customizable via setValueSeparator(String).

Example XML property with default value: 

   <property name="url" value="jdbc:${dbname:defaultdb}" />
Since:
3.1
Author:
Chris Beams, Juergen Hoeller
See Also:

  • Field Details

    • DEFAULT_PLACEHOLDER_PREFIX

      public static final String DEFAULT_PLACEHOLDER_PREFIX
      Default placeholder prefix: "${".
      See Also:

    • DEFAULT_PLACEHOLDER_SUFFIX

      public static final String DEFAULT_PLACEHOLDER_SUFFIX
      Default placeholder suffix: "}".
      See Also:

    • DEFAULT_VALUE_SEPARATOR

      public static final String DEFAULT_VALUE_SEPARATOR
      Default value separator: ":".
      See Also:

    • placeholderPrefix

      protected String placeholderPrefix
      Defaults to "${".

    • placeholderSuffix

      protected String placeholderSuffix
      Defaults to "}".

    • valueSeparator

      @Nullable protected String valueSeparator
      Defaults to ":".

    • trimValues

      protected boolean trimValues

    • nullValue

      @Nullable protected String nullValue

    • ignoreUnresolvablePlaceholders

      protected boolean ignoreUnresolvablePlaceholders

  • Constructor Details

    • PlaceholderConfigurerSupport

      public PlaceholderConfigurerSupport()

  • Method Details

    • setPlaceholderPrefix

      public void setPlaceholderPrefix(String placeholderPrefix)
      Set the prefix that a placeholder string starts with. The default is "${".

    • setPlaceholderSuffix

      public void setPlaceholderSuffix(String placeholderSuffix)
      Set the suffix that a placeholder string ends with. The default is "}".

    • setValueSeparator

      public void setValueSeparator(@Nullable String valueSeparator)
      Specify the separating character between the placeholder variable and the associated default value, or null if no such special character should be processed as a value separator. The default is ":".

    • setTrimValues

      public void setTrimValues(boolean trimValues)
      Specify whether to trim resolved values before applying them, removing superfluous whitespace from the beginning and end.

      Default is false.

      Since:
      4.3

    • setNullValue

      public void setNullValue(String nullValue)
      Set a value that should be treated as null when resolved as a placeholder value: e.g. "" (empty String) or "null".

      Note that this will only apply to full property values, not to parts of concatenated values.

      By default, no such null value is defined. This means that there is no way to express null as a property value unless you explicitly map a corresponding value here.

    • setIgnoreUnresolvablePlaceholders

      public void setIgnoreUnresolvablePlaceholders(boolean ignoreUnresolvablePlaceholders)
      Set whether to ignore unresolvable placeholders.

      Default is "false": An exception will be thrown if a placeholder fails to resolve. Switch this flag to "true" in order to preserve the placeholder String as-is in such a case, leaving it up to other placeholder configurers to resolve it.

    • setBeanName

      public void setBeanName(String beanName)
      Only necessary to check that we're not parsing our own bean definition, to avoid failing on unresolvable placeholders in properties file locations. The latter case can happen with placeholders for system properties in resource locations.
      Specified by:
      setBeanName in interface BeanNameAware
      Parameters:
      beanName - the name of the bean in the factory. Note that this name is the actual bean name used in the factory, which may differ from the originally specified name: in particular for inner bean names, the actual bean name might have been made unique through appending "#..." suffixes. Use the BeanFactoryUtils.originalBeanName(String) method to extract the original bean name (without suffix), if desired.
      See Also:

    • setBeanFactory

      public void setBeanFactory(BeanFactory beanFactory)
      Only necessary to check that we're not parsing our own bean definition, to avoid failing on unresolvable placeholders in properties file locations. The latter case can happen with placeholders for system properties in resource locations.
      Specified by:
      setBeanFactory in interface BeanFactoryAware
      Parameters:
      beanFactory - owning BeanFactory (never null). The bean can immediately call methods on the factory.
      See Also:

    • doProcessProperties

      protected void doProcessProperties(ConfigurableListableBeanFactory beanFactoryToProcess, StringValueResolver valueResolver)