Spring Framework

org.springframework.beans.factory.config
Class PlaceholderConfigurerSupport

java.lang.Object
  extended by org.springframework.core.io.support.PropertiesLoaderSupport
      extended by org.springframework.beans.factory.config.PropertyResourceConfigurer
          extended by 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 default 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:
PropertyPlaceholderConfigurer, PropertySourcesPlaceholderConfigurer

Field Summary
static java.lang.String DEFAULT_PLACEHOLDER_PREFIX
          Default placeholder prefix: "${"
static java.lang.String DEFAULT_PLACEHOLDER_SUFFIX
          Default placeholder suffix: "}"
static java.lang.String DEFAULT_VALUE_SEPARATOR
          Default value separator: ":"
protected  boolean ignoreUnresolvablePlaceholders
           
protected  java.lang.String nullValue
           
protected  java.lang.String placeholderPrefix
          Defaults to "${"
protected  java.lang.String placeholderSuffix
          Defaults to "}"
protected  java.lang.String valueSeparator
          Defaults to ":"
 
Fields inherited from class org.springframework.core.io.support.PropertiesLoaderSupport
localOverride, localProperties, logger, XML_FILE_EXTENSION
 
Fields inherited from interface org.springframework.core.Ordered
HIGHEST_PRECEDENCE, LOWEST_PRECEDENCE
 
Constructor Summary
PlaceholderConfigurerSupport()
           
 
Method Summary
protected  void doProcessProperties(ConfigurableListableBeanFactory beanFactoryToProcess, StringValueResolver valueResolver)
           
 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.
 void setBeanName(java.lang.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.
 void setIgnoreUnresolvablePlaceholders(boolean ignoreUnresolvablePlaceholders)
          Set whether to ignore unresolvable placeholders.
 void setNullValue(java.lang.String nullValue)
          Set a value that should be treated as null when resolved as a placeholder value: e.g.
 void setPlaceholderPrefix(java.lang.String placeholderPrefix)
          Set the prefix that a placeholder string starts with.
 void setPlaceholderSuffix(java.lang.String placeholderSuffix)
          Set the suffix that a placeholder string ends with.
 void setValueSeparator(java.lang.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.
 
Methods inherited from class org.springframework.beans.factory.config.PropertyResourceConfigurer
convertProperties, convertProperty, convertPropertyValue, getOrder, postProcessBeanFactory, processProperties, setOrder
 
Methods inherited from class org.springframework.core.io.support.PropertiesLoaderSupport
loadProperties, mergeProperties, setFileEncoding, setIgnoreResourceNotFound, setLocalOverride, setLocation, setLocations, setProperties, setPropertiesArray, setPropertiesPersister
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Field Detail

DEFAULT_PLACEHOLDER_PREFIX

public static final java.lang.String DEFAULT_PLACEHOLDER_PREFIX
Default placeholder prefix: "${"

See Also:
Constant Field Values

DEFAULT_PLACEHOLDER_SUFFIX

public static final java.lang.String DEFAULT_PLACEHOLDER_SUFFIX
Default placeholder suffix: "}"

See Also:
Constant Field Values

DEFAULT_VALUE_SEPARATOR

public static final java.lang.String DEFAULT_VALUE_SEPARATOR
Default value separator: ":"

See Also:
Constant Field Values

placeholderPrefix

protected java.lang.String placeholderPrefix
Defaults to "${"


placeholderSuffix

protected java.lang.String placeholderSuffix
Defaults to "}"


valueSeparator

protected java.lang.String valueSeparator
Defaults to ":"


ignoreUnresolvablePlaceholders

protected boolean ignoreUnresolvablePlaceholders

nullValue

protected java.lang.String nullValue
Constructor Detail

PlaceholderConfigurerSupport

public PlaceholderConfigurerSupport()
Method Detail

setPlaceholderPrefix

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


setPlaceholderSuffix

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


setValueSeparator

public void setValueSeparator(java.lang.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 ":".


setNullValue

public void setNullValue(java.lang.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(java.lang.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:
PropertiesLoaderSupport.setLocations(org.springframework.core.io.Resource[]), ResourceEditor

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:
PropertiesLoaderSupport.setLocations(org.springframework.core.io.Resource[]), ResourceEditor

doProcessProperties

protected void doProcessProperties(ConfigurableListableBeanFactory beanFactoryToProcess,
                                   StringValueResolver valueResolver)

Spring Framework