org.springframework.beans.factory.config
Class PropertyPlaceholderConfigurer

java.lang.Object
  org.springframework.core.io.support.PropertiesLoaderSupport
      org.springframework.beans.factory.config.PropertyResourceConfigurer
          org.springframework.beans.factory.config.PlaceholderConfigurerSupport
              org.springframework.beans.factory.config.PropertyPlaceholderConfigurer

All Implemented Interfaces:

Aware, BeanFactoryAware, BeanNameAware, BeanFactoryPostProcessor, Ordered, PriorityOrdered

Direct Known Subclasses:

PreferencesPlaceholderConfigurer, ServletContextPropertyPlaceholderConfigurer

public class PropertyPlaceholderConfigurer
extends PlaceholderConfigurerSupport

PlaceholderConfigurerSupport subclass that resolves ${...} placeholders against local properties and/or system properties and environment variables.

As of Spring 3.1, PropertySourcesPlaceholderConfigurer should be used preferentially over this implementation; it is more flexible through taking advantage of the Environment and PropertySource mechanisms also made available in Spring 3.1.

PropertyPlaceholderConfigurer is still appropriate for use when:

• the spring-context module is not available (i.e., one is using Spring's BeanFactory API as opposed to ApplicationContext).
• existing configuration makes use of the "systemPropertiesMode" and/or "systemPropertiesModeName" properties. Users are encouraged to move away from using these settings, and rather configure property source search order through the container's Environment; however, exact preservation of functionality may be maintained by continuing to use PropertyPlaceholderConfigurer.

Prior to Spring 3.1, the <context:property-placeholder/> namespace element registered an instance of PropertyPlaceholderConfigurer. It will still do so if using the spring-context-3.0.xsd definition of the namespace. That is, you can preserve registration of PropertyPlaceholderConfigurer through the namespace, even if using Spring 3.1; simply do not update your xsi:schemaLocation and continue using the 3.0 XSD.

Since:

02.10.2003

Author:

Juergen Hoeller, Chris Beams

See Also:

setSystemPropertiesModeName(java.lang.String), PlaceholderConfigurerSupport, PropertyOverrideConfigurer, PropertySourcesPlaceholderConfigurer

Field Summary

static int	SYSTEM_PROPERTIES_MODE_FALLBACK Check system properties if not resolvable in the specified properties.
static int	SYSTEM_PROPERTIES_MODE_NEVER Never check system properties.
static int	SYSTEM_PROPERTIES_MODE_OVERRIDE Check system properties first, before trying the specified properties.

Fields inherited from class org.springframework.beans.factory.config.PlaceholderConfigurerSupport

DEFAULT_PLACEHOLDER_PREFIX, DEFAULT_PLACEHOLDER_SUFFIX, DEFAULT_VALUE_SEPARATOR, ignoreUnresolvablePlaceholders, nullValue, placeholderPrefix, placeholderSuffix, valueSeparator

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

PropertyPlaceholderConfigurer()

Method Summary

protected String	parseStringValue(String strVal, Properties props, Set<?> visitedPlaceholders) Deprecated. as of Spring 3.0, in favor of using resolvePlaceholder(java.lang.String, java.util.Properties, int) with PropertyPlaceholderHelper. Only retained for compatibility with Spring 2.5 extensions.
protected void	processProperties(ConfigurableListableBeanFactory beanFactoryToProcess, Properties props) Visit each bean definition in the given bean factory and attempt to replace ${...} property placeholders with values from the given properties.
protected String	resolvePlaceholder(String placeholder, Properties props) Resolve the given placeholder using the given properties.
protected String	resolvePlaceholder(String placeholder, Properties props, int systemPropertiesMode) Resolve the given placeholder using the given properties, performing a system properties check according to the given mode.
protected String	resolveSystemProperty(String key) Resolve the given key as JVM system property, and optionally also as system environment variable if no matching system property has been found.
void	setSearchSystemEnvironment(boolean searchSystemEnvironment) Set whether to search for a matching system environment variable if no matching system property has been found.
void	setSystemPropertiesMode(int systemPropertiesMode) Set how to check system properties: as fallback, as override, or never.
void	setSystemPropertiesModeName(String constantName) Set the system property mode by the name of the corresponding constant, e.g.

Methods inherited from class org.springframework.beans.factory.config.PlaceholderConfigurerSupport

doProcessProperties, setBeanFactory, setBeanName, setIgnoreUnresolvablePlaceholders, setNullValue, setPlaceholderPrefix, setPlaceholderSuffix, setValueSeparator

Methods inherited from class org.springframework.beans.factory.config.PropertyResourceConfigurer

convertProperties, convertProperty, convertPropertyValue, getOrder, postProcessBeanFactory, 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

SYSTEM_PROPERTIES_MODE_NEVER

public static final int SYSTEM_PROPERTIES_MODE_NEVER

Never check system properties.

See Also:

Constant Field Values

SYSTEM_PROPERTIES_MODE_FALLBACK

public static final int SYSTEM_PROPERTIES_MODE_FALLBACK

Check system properties if not resolvable in the specified properties. This is the default.

See Also:

Constant Field Values

SYSTEM_PROPERTIES_MODE_OVERRIDE

public static final int SYSTEM_PROPERTIES_MODE_OVERRIDE

Check system properties first, before trying the specified properties. This allows system properties to override any other property source.

See Also:

Constant Field Values

Constructor Detail

PropertyPlaceholderConfigurer

public PropertyPlaceholderConfigurer()

Method Detail

setSystemPropertiesModeName

public void setSystemPropertiesModeName(String constantName)
                                 throws IllegalArgumentException

Set the system property mode by the name of the corresponding constant, e.g. "SYSTEM_PROPERTIES_MODE_OVERRIDE".

Parameters:

constantName - name of the constant

Throws:

IllegalArgumentException - if an invalid constant was specified

See Also:

setSystemPropertiesMode(int)

setSystemPropertiesMode

public void setSystemPropertiesMode(int systemPropertiesMode)

Set how to check system properties: as fallback, as override, or never. For example, will resolve ${user.dir} to the "user.dir" system property.

The default is "fallback": If not being able to resolve a placeholder with the specified properties, a system property will be tried. "override" will check for a system property first, before trying the specified properties. "never" will not check system properties at all.

See Also:

SYSTEM_PROPERTIES_MODE_NEVER, SYSTEM_PROPERTIES_MODE_FALLBACK, SYSTEM_PROPERTIES_MODE_OVERRIDE, setSystemPropertiesModeName(java.lang.String)

setSearchSystemEnvironment

public void setSearchSystemEnvironment(boolean searchSystemEnvironment)

Set whether to search for a matching system environment variable if no matching system property has been found. Only applied when "systemPropertyMode" is active (i.e. "fallback" or "override"), right after checking JVM system properties.

Default is "true". Switch this setting off to never resolve placeholders against system environment variables. Note that it is generally recommended to pass external values in as JVM system properties: This can easily be achieved in a startup script, even for existing environment variables.

NOTE: Access to environment variables does not work on the Sun VM 1.4, where the corresponding System.getenv(java.lang.String) support was disabled - before it eventually got re-enabled for the Sun VM 1.5. Please upgrade to 1.5 (or higher) if you intend to rely on the environment variable support.

See Also:

setSystemPropertiesMode(int), System.getProperty(String), System.getenv(String)

resolvePlaceholder

protected String resolvePlaceholder(String placeholder,
                                    Properties props,
                                    int systemPropertiesMode)

Resolve the given placeholder using the given properties, performing a system properties check according to the given mode.

The default implementation delegates to resolvePlaceholder (placeholder, props) before/after the system properties check.

Subclasses can override this for custom resolution strategies, including customized points for the system properties check.

Parameters:

placeholder - the placeholder to resolve

props - the merged properties of this configurer

systemPropertiesMode - the system properties mode, according to the constants in this class

Returns:

the resolved value, of null if none

See Also:

setSystemPropertiesMode(int), System.getProperty(java.lang.String), resolvePlaceholder(String, java.util.Properties)

resolvePlaceholder

protected String resolvePlaceholder(String placeholder,
                                    Properties props)

Resolve the given placeholder using the given properties. The default implementation simply checks for a corresponding property key.

Subclasses can override this for customized placeholder-to-key mappings or custom resolution strategies, possibly just using the given properties as fallback.

Note that system properties will still be checked before respectively after this method is invoked, according to the system properties mode.

Parameters:

placeholder - the placeholder to resolve

props - the merged properties of this configurer

Returns:

the resolved value, of null if none

See Also:

setSystemPropertiesMode(int)

resolveSystemProperty

protected String resolveSystemProperty(String key)

Resolve the given key as JVM system property, and optionally also as system environment variable if no matching system property has been found.

Parameters:

key - the placeholder to resolve as system property key

Returns:

the system property value, or null if not found

See Also:

setSearchSystemEnvironment(boolean), System.getProperty(String), System.getenv(String)

processProperties

protected void processProperties(ConfigurableListableBeanFactory beanFactoryToProcess,
                                 Properties props)
                          throws BeansException

Visit each bean definition in the given bean factory and attempt to replace ${...} property placeholders with values from the given properties.

Specified by:

processProperties in class PropertyResourceConfigurer

Parameters:

beanFactoryToProcess - the BeanFactory used by the application context

props - the Properties to apply

Throws:

BeansException - in case of errors

parseStringValue

@Deprecated
protected String parseStringValue(String strVal,
                                             Properties props,
                                             Set<?> visitedPlaceholders)

Deprecated. as of Spring 3.0, in favor of using resolvePlaceholder(java.lang.String, java.util.Properties, int) with PropertyPlaceholderHelper. Only retained for compatibility with Spring 2.5 extensions.

Parse the given String value for placeholder resolution.

Parameters:

strVal - the String value to parse

props - the Properties to resolve placeholders against

visitedPlaceholders - the placeholders that have already been visited during the current resolution attempt (ignored in this version of the code)