org.springframework.beans.factory.config.PropertyPlaceholderConfigurer Maven / Gradle / Ivy
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* Copyright 2002-2019 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.springframework.beans.factory.config;
import java.util.Properties;
import org.springframework.beans.BeansException;
import org.springframework.core.Constants;
import org.springframework.core.SpringProperties;
import org.springframework.core.env.AbstractEnvironment;
import org.springframework.lang.Nullable;
import org.springframework.util.PropertyPlaceholderHelper;
import org.springframework.util.PropertyPlaceholderHelper.PlaceholderResolver;
import org.springframework.util.StringValueResolver;
/**
* {@link PlaceholderConfigurerSupport} subclass that resolves ${...} placeholders against
* {@link #setLocation local} {@link #setProperties properties} and/or system properties
* and environment variables.
*
* As of Spring 3.1, {@link org.springframework.context.support.PropertySourcesPlaceholderConfigurer
* PropertySourcesPlaceholderConfigurer} should be used preferentially over this implementation; it is
* more flexible through taking advantage of the {@link org.springframework.core.env.Environment} and
* {@link org.springframework.core.env.PropertySource} mechanisms also made available in Spring 3.1.
*
*
{@link PropertyPlaceholderConfigurer} is still appropriate for use when:
*
* - the {@code spring-context} module is not available (i.e., one is using Spring's
* {@code BeanFactory} API as opposed to {@code ApplicationContext}).
*
- existing configuration makes use of the {@link #setSystemPropertiesMode(int) "systemPropertiesMode"}
* and/or {@link #setSystemPropertiesModeName(String) "systemPropertiesModeName"} properties.
* Users are encouraged to move away from using these settings, and rather configure property
* source search order through the container's {@code Environment}; however, exact preservation
* of functionality may be maintained by continuing to use {@code PropertyPlaceholderConfigurer}.
*
*
* @author Juergen Hoeller
* @author Chris Beams
* @since 02.10.2003
* @see #setSystemPropertiesModeName
* @see PlaceholderConfigurerSupport
* @see PropertyOverrideConfigurer
* @see org.springframework.context.support.PropertySourcesPlaceholderConfigurer
*/
public class PropertyPlaceholderConfigurer extends PlaceholderConfigurerSupport {
/** Never check system properties. */
public static final int SYSTEM_PROPERTIES_MODE_NEVER = 0;
/**
* Check system properties if not resolvable in the specified properties.
* This is the default.
*/
public static final int SYSTEM_PROPERTIES_MODE_FALLBACK = 1;
/**
* Check system properties first, before trying the specified properties.
* This allows system properties to override any other property source.
*/
public static final int SYSTEM_PROPERTIES_MODE_OVERRIDE = 2;
private static final Constants constants = new Constants(PropertyPlaceholderConfigurer.class);
private int systemPropertiesMode = SYSTEM_PROPERTIES_MODE_FALLBACK;
private boolean searchSystemEnvironment =
!SpringProperties.getFlag(AbstractEnvironment.IGNORE_GETENV_PROPERTY_NAME);
/**
* Set the system property mode by the name of the corresponding constant,
* e.g. "SYSTEM_PROPERTIES_MODE_OVERRIDE".
* @param constantName name of the constant
* @see #setSystemPropertiesMode
*/
public void setSystemPropertiesModeName(String constantName) throws IllegalArgumentException {
this.systemPropertiesMode = constants.asNumber(constantName).intValue();
}
/**
* 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 #SYSTEM_PROPERTIES_MODE_NEVER
* @see #SYSTEM_PROPERTIES_MODE_FALLBACK
* @see #SYSTEM_PROPERTIES_MODE_OVERRIDE
* @see #setSystemPropertiesModeName
*/
public void setSystemPropertiesMode(int systemPropertiesMode) {
this.systemPropertiesMode = systemPropertiesMode;
}
/**
* 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.
* @see #setSystemPropertiesMode
* @see System#getProperty(String)
* @see System#getenv(String)
*/
public void setSearchSystemEnvironment(boolean searchSystemEnvironment) {
this.searchSystemEnvironment = searchSystemEnvironment;
}
/**
* Resolve the given placeholder using the given properties, performing
* a system properties check according to the given mode.
*
The default implementation delegates to {@code 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.
* @param placeholder the placeholder to resolve
* @param props the merged properties of this configurer
* @param systemPropertiesMode the system properties mode,
* according to the constants in this class
* @return the resolved value, of null if none
* @see #setSystemPropertiesMode
* @see System#getProperty
* @see #resolvePlaceholder(String, java.util.Properties)
*/
@Nullable
protected String resolvePlaceholder(String placeholder, Properties props, int systemPropertiesMode) {
String propVal = null;
if (systemPropertiesMode == SYSTEM_PROPERTIES_MODE_OVERRIDE) {
propVal = resolveSystemProperty(placeholder);
}
if (propVal == null) {
propVal = resolvePlaceholder(placeholder, props);
}
if (propVal == null && systemPropertiesMode == SYSTEM_PROPERTIES_MODE_FALLBACK) {
propVal = resolveSystemProperty(placeholder);
}
return propVal;
}
/**
* 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.
* @param placeholder the placeholder to resolve
* @param props the merged properties of this configurer
* @return the resolved value, of {@code null} if none
* @see #setSystemPropertiesMode
*/
@Nullable
protected String resolvePlaceholder(String placeholder, Properties props) {
return props.getProperty(placeholder);
}
/**
* Resolve the given key as JVM system property, and optionally also as
* system environment variable if no matching system property has been found.
* @param key the placeholder to resolve as system property key
* @return the system property value, or {@code null} if not found
* @see #setSearchSystemEnvironment
* @see System#getProperty(String)
* @see System#getenv(String)
*/
@Nullable
protected String resolveSystemProperty(String key) {
try {
String value = System.getProperty(key);
if (value == null && this.searchSystemEnvironment) {
value = System.getenv(key);
}
return value;
}
catch (Throwable ex) {
if (logger.isDebugEnabled()) {
logger.debug("Could not access system property '" + key + "': " + ex);
}
return null;
}
}
/**
* Visit each bean definition in the given bean factory and attempt to replace ${...} property
* placeholders with values from the given properties.
*/
@Override
protected void processProperties(ConfigurableListableBeanFactory beanFactoryToProcess, Properties props)
throws BeansException {
StringValueResolver valueResolver = new PlaceholderResolvingStringValueResolver(props);
doProcessProperties(beanFactoryToProcess, valueResolver);
}
private class PlaceholderResolvingStringValueResolver implements StringValueResolver {
private final PropertyPlaceholderHelper helper;
private final PlaceholderResolver resolver;
public PlaceholderResolvingStringValueResolver(Properties props) {
this.helper = new PropertyPlaceholderHelper(
placeholderPrefix, placeholderSuffix, valueSeparator, ignoreUnresolvablePlaceholders);
this.resolver = new PropertyPlaceholderConfigurerResolver(props);
}
@Override
@Nullable
public String resolveStringValue(String strVal) throws BeansException {
String resolved = this.helper.replacePlaceholders(strVal, this.resolver);
if (trimValues) {
resolved = resolved.trim();
}
return (resolved.equals(nullValue) ? null : resolved);
}
}
private final class PropertyPlaceholderConfigurerResolver implements PlaceholderResolver {
private final Properties props;
private PropertyPlaceholderConfigurerResolver(Properties props) {
this.props = props;
}
@Override
@Nullable
public String resolvePlaceholder(String placeholderName) {
return PropertyPlaceholderConfigurer.this.resolvePlaceholder(placeholderName,
this.props, systemPropertiesMode);
}
}
}