Spring Framework 6.1.4 · org.springframework.beans.factory.config.PlaceholderConfigurerSupport

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}" />

Field Summary

Modifier and Type	Field and Description
private BeanFactory	beanFactory
private String	beanName
public static final String	DEFAULT_PLACEHOLDER_PREFIX Default placeholder prefix: ${.
public static final String	DEFAULT_PLACEHOLDER_SUFFIX Default placeholder suffix: }.
public static final String	DEFAULT_VALUE_SEPARATOR Default value separator: :.
protected boolean	ignoreUnresolvablePlaceholders
protected String	nullValue
protected String	placeholderPrefix Defaults to ${.
protected String	placeholderSuffix Defaults to }.
protected boolean	trimValues
protected String	valueSeparator Defaults to :.

Constructor Summary

Access	Constructor and Description
public	PlaceholderConfigurerSupport()

Method Summary

Modifier and Type	Method and Description
protected void	doProcessProperties(ConfigurableListableBeanFactory beanFactoryToProcess, StringValueResolver valueResolver)
public void	setBeanFactory(BeanFactory owning BeanFactory (never `null`). The bean can immediately call methods on the factory. beanFactory) Implements org.springframework.beans.factory.BeanFactoryAware.setBeanFactory. Only necessary to check that we're not parsing our own bean definition, to avoid failing on unresolvable placeholders in properties file locations.
public void	setBeanName(String 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. beanName) Implements org.springframework.beans.factory.BeanNameAware.setBeanName. Only necessary to check that we're not parsing our own bean definition, to avoid failing on unresolvable placeholders in properties file locations.
public void	setIgnoreUnresolvablePlaceholders(boolean ignoreUnresolvablePlaceholders) Set whether to ignore unresolvable placeholders.
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".
public void	setPlaceholderPrefix(String placeholderPrefix) Set the prefix that a placeholder string starts with.
public void	setPlaceholderSuffix(String placeholderSuffix) Set the suffix that a placeholder string ends with.
public void	setTrimValues(boolean trimValues) Specify whether to trim resolved values before applying them, removing superfluous whitespace from the beginning and end.
public void	setValueSeparator(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.

Inherited from org.springframework.beans.factory.config.PropertyResourceConfigurer:: convertProperties convertProperty convertPropertyValue getOrder postProcessBeanFactory processProperties setOrder

Field Detail

beanFactory	back to summary
private BeanFactory beanFactory Annotations @Nullable

beanName	back to summary
private String beanName Annotations @Nullable

DEFAULT_PLACEHOLDER_PREFIX	back to summary
public static final String DEFAULT_PLACEHOLDER_PREFIX Default placeholder prefix: ${.

DEFAULT_PLACEHOLDER_SUFFIX	back to summary
public static final String DEFAULT_PLACEHOLDER_SUFFIX Default placeholder suffix: }.

DEFAULT_VALUE_SEPARATOR	back to summary
public static final String DEFAULT_VALUE_SEPARATOR Default value separator: :.

ignoreUnresolvablePlaceholders	back to summary
protected boolean ignoreUnresolvablePlaceholders

nullValue	back to summary
protected String nullValue Annotations @Nullable

placeholderPrefix	back to summary
protected String placeholderPrefix Defaults to ${.

placeholderSuffix	back to summary
protected String placeholderSuffix Defaults to }.

trimValues	back to summary
protected boolean trimValues

valueSeparator	back to summary
protected String valueSeparator Defaults to :. Annotations @Nullable

Constructor Detail

PlaceholderConfigurerSupport	back to summary
public PlaceholderConfigurerSupport()

Method Detail

doProcessProperties	back to summary
protected void doProcessProperties(ConfigurableListableBeanFactory beanFactoryToProcess, StringValueResolver valueResolver)

setBeanFactory back to summary

setBeanFactory	back to summary
public void setBeanFactory(BeanFactory beanFactory) Implements org.springframework.beans.factory.BeanFactoryAware.setBeanFactory. 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. Parameters beanFactory:BeanFactory Doc from org.springframework.beans.factory.BeanFactoryAware.setBeanFactory. owning BeanFactory (never `null`). The bean can immediately call methods on the factory. Annotations @Override See Also `setLocations`, `org.springframework.core.io.ResourceEditor`

public void setBeanFactory(BeanFactory beanFactory)

Implements org.springframework.beans.factory.BeanFactoryAware.setBeanFactory.

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.

Parameters

beanFactory:BeanFactory

Doc from org.springframework.beans.factory.BeanFactoryAware.setBeanFactory.

owning BeanFactory (never null). The bean can immediately call methods on the factory.

Annotations

@Override

setBeanName back to summary

setBeanName	back to summary
public void setBeanName(String beanName) Implements org.springframework.beans.factory.BeanNameAware.setBeanName. 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. Parameters beanName:String Doc from org.springframework.beans.factory.BeanNameAware.setBeanName. 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. Annotations @Override See Also `setLocations`, `org.springframework.core.io.ResourceEditor`

public void setBeanName(String beanName)

Implements org.springframework.beans.factory.BeanNameAware.setBeanName.

Parameters

beanName:String

Doc from org.springframework.beans.factory.BeanNameAware.setBeanName.

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.

Annotations

@Override

setIgnoreUnresolvablePlaceholders	back to summary
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.

setIgnoreUnresolvablePlaceholders

back to summary

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.

setNullValue back to summary

setNullValue	back to summary
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.

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.

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

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

setTrimValues back to summary

setTrimValues	back to summary
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

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

setValueSeparator	back to summary
public void setValueSeparator(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 :.