PropertyPlaceholderConfigurer supports "${myKey:myDefaultValue}" defaulting syntax

org.springframework.beans/src/main/java/org/springframework/beans/factory/config/PropertyPlaceholderConfigurer.java

@@ -99,6 +99,9 @@ public class PropertyPlaceholderConfigurer extends PropertyResourceConfigurer
 	/** Default placeholder suffix: "}" */
 	public static final String DEFAULT_PLACEHOLDER_SUFFIX = "}";
 
+	/** Default value separator: ":" */
+	public static final String DEFAULT_VALUE_SEPARATOR = ":";
+
 
 	/** Never check system properties. */
 	public static final int SYSTEM_PROPERTIES_MODE_NEVER = 0;
@@ -122,6 +125,8 @@ public class PropertyPlaceholderConfigurer extends PropertyResourceConfigurer
 
 	private String placeholderSuffix = DEFAULT_PLACEHOLDER_SUFFIX;
 
+	private String valueSeparator = DEFAULT_VALUE_SEPARATOR;
+
 	private int systemPropertiesMode = SYSTEM_PROPERTIES_MODE_FALLBACK;
 
 	private boolean searchSystemEnvironment = true;
@@ -360,7 +365,8 @@ public class PropertyPlaceholderConfigurer extends PropertyResourceConfigurer
 		private final PlaceholderResolver resolver;
 
 		public PlaceholderResolvingStringValueResolver(Properties props) {
-			this.helper = new PropertyPlaceholderHelper(placeholderPrefix, placeholderSuffix, ignoreUnresolvablePlaceholders);
+			this.helper = new PropertyPlaceholderHelper(
+					placeholderPrefix, placeholderSuffix, valueSeparator, ignoreUnresolvablePlaceholders);
 			this.resolver = new PropertyPlaceholderConfigurerResolver(props);
 		}
 
@@ -370,6 +376,7 @@ public class PropertyPlaceholderConfigurer extends PropertyResourceConfigurer
 		}
 	}
 
+
 	private class PropertyPlaceholderConfigurerResolver implements PlaceholderResolver {
 
 		private final Properties props;

org.springframework.beans/src/test/java/org/springframework/beans/factory/config/PropertyResourceConfigurerTests.java

@@ -662,6 +662,19 @@ public final class PropertyResourceConfigurerTests {
 		assertEquals("mytest", tb.getTouchy());
 	}
 
+	@Test
+	public void testPropertyPlaceholderConfigurerWithInlineDefault() {
+		factory.registerBeanDefinition("tb",
+			genericBeanDefinition(TestBean.class)
+			.addPropertyValue("touchy", "${test:mytest}").getBeanDefinition());
+
+		PropertyPlaceholderConfigurer ppc = new PropertyPlaceholderConfigurer();
+		ppc.postProcessBeanFactory(factory);
+
+		TestBean tb = (TestBean) factory.getBean("tb");
+		assertEquals("mytest", tb.getTouchy());
+	}
+
 	@Test
 	public void testPropertyPlaceholderConfigurerWithAliases() {
 		factory.registerBeanDefinition("tb",

org.springframework.core/src/main/java/org/springframework/util/PropertyPlaceholderHelper.java

@@ -16,18 +16,18 @@
 
 package org.springframework.util;
 
+import java.util.HashSet;
 import java.util.Properties;
 import java.util.Set;
-import java.util.HashSet;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
 /**
  * Utility class for working with Strings that have placeholder values in them. A placeholder takes the form
- * <code>${name}</code>. Using <code>PropertyPlaceholderUtils</code> these placeholders can be substituted for
- * user-supplied values. <p> Values for substitution can be supplied using a {@link Properties} instance or using a
- * {@link PlaceholderResolver}.
+ * <code>${name}</code>. Using <code>PropertyPlaceholderHelper</code> these placeholders can be substituted for
+ * user-supplied values. <p> Values for substitution can be supplied using a {@link Properties} instance or
+ * using a {@link PlaceholderResolver}.
  *
  * @author Juergen Hoeller
  * @author Rob Harrop
@@ -35,46 +35,49 @@ import org.apache.commons.logging.LogFactory;
  */
 public class PropertyPlaceholderHelper {
 
-	private static final Log LOGGER = LogFactory.getLog(PropertyPlaceholderHelper.class);
+	private static final Log logger = LogFactory.getLog(PropertyPlaceholderHelper.class);
 
 	private final String placeholderPrefix;
 
 	private final String placeholderSuffix;
 
+	private final String valueSeparator;
+
 	private final boolean ignoreUnresolvablePlaceholders;
 
+
 	/**
-	 * Creates a new <code>PropertyPlaceholderHelper</code> that uses the supplied prefix and suffix. Unresolvable
-	 * placeholders are ignored.
-	 *
+	 * Creates a new <code>PropertyPlaceholderHelper</code> that uses the supplied prefix and suffix.
+	 * Unresolvable placeholders are ignored.
 	 * @param placeholderPrefix the prefix that denotes the start of a placeholder.
 	 * @param placeholderSuffix the suffix that denotes the end of a placeholder.
 	 */
 	public PropertyPlaceholderHelper(String placeholderPrefix, String placeholderSuffix) {
-		this(placeholderPrefix, placeholderSuffix, true);
+		this(placeholderPrefix, placeholderSuffix, null, true);
 	}
 
 	/**
 	 * Creates a new <code>PropertyPlaceholderHelper</code> that uses the supplied prefix and suffix.
-	 *
 	 * @param placeholderPrefix the prefix that denotes the start of a placeholder.
 	 * @param placeholderSuffix the suffix that denotes the end of a placeholder.
 	 * @param ignoreUnresolvablePlaceholders indicates whether unresolvable placeholders should be ignored
 	 * (<code>true</code>) or cause an exception (<code>false</code>).
 	 */
 	public PropertyPlaceholderHelper(String placeholderPrefix, String placeholderSuffix,
-			boolean ignoreUnresolvablePlaceholders) {
-		Assert.notNull(placeholderPrefix, "Argument 'placeholderPrefix' must not be null.");
-		Assert.notNull(placeholderSuffix, "Argument 'placeholderSuffix' must not be null.");
+			String valueSeparator, boolean ignoreUnresolvablePlaceholders) {
+
+		Assert.notNull(placeholderPrefix, "placeholderPrefix must not be null");
+		Assert.notNull(placeholderSuffix, "placeholderSuffix must not be null");
 		this.placeholderPrefix = placeholderPrefix;
 		this.placeholderSuffix = placeholderSuffix;
+		this.valueSeparator = valueSeparator;
 		this.ignoreUnresolvablePlaceholders = ignoreUnresolvablePlaceholders;
 	}
 
+
 	/**
-	 * Replaces all placeholders of format <code>${name}</code> with the corresponding property from the supplied {@link
-	 * Properties}.
-	 *
+	 * Replaces all placeholders of format <code>${name}</code> with the corresponding property
+	 * from the supplied {@link Properties}.
 	 * @param value the value containing the placeholders to be replaced.
 	 * @param properties the <code>Properties</code> to use for replacement.
 	 * @return the supplied value with placeholders replaced inline.
@@ -82,7 +85,6 @@ public class PropertyPlaceholderHelper {
 	public String replacePlaceholders(String value, final Properties properties) {
 		Assert.notNull(properties, "Argument 'properties' must not be null.");
 		return replacePlaceholders(value, new PlaceholderResolver() {
-
 			public String resolvePlaceholder(String placeholderName) {
 				return properties.getProperty(placeholderName);
 			}
@@ -90,9 +92,8 @@ public class PropertyPlaceholderHelper {
 	}
 
 	/**
-	 * Replaces all placeholders of format <code>${name}</code> with the value returned from the supplied {@link
-	 * PlaceholderResolver}.
-	 *
+	 * Replaces all placeholders of format <code>${name}</code> with the value returned from the supplied
+	 * {@link PlaceholderResolver}.
 	 * @param value the value containing the placeholders to be replaced.
 	 * @param placeholderResolver the <code>PlaceholderResolver</code> to use for replacement.
 	 * @return the supplied value with placeholders replaced inline.
@@ -102,8 +103,9 @@ public class PropertyPlaceholderHelper {
 		return parseStringValue(value, placeholderResolver, new HashSet<String>());
 	}
 
-	protected String parseStringValue(String strVal, PlaceholderResolver placeholderResolver,
-			Set<String> visitedPlaceholders) {
+	protected String parseStringValue(
+			String strVal, PlaceholderResolver placeholderResolver, Set<String> visitedPlaceholders) {
+
 		StringBuilder buf = new StringBuilder(strVal);
 
 		int startIndex = strVal.indexOf(this.placeholderPrefix);
@@ -120,14 +122,25 @@ public class PropertyPlaceholderHelper {
 
 				// Now obtain the value for the fully resolved key...
 				String propVal = placeholderResolver.resolvePlaceholder(placeholder);
+				if (propVal == null && this.valueSeparator != null) {
+					int separatorIndex = placeholder.indexOf(this.valueSeparator);
+					if (separatorIndex != -1) {
+						String actualPlaceholder = placeholder.substring(0, separatorIndex);
+						String defaultValue = placeholder.substring(separatorIndex + this.valueSeparator.length());
+						propVal = placeholderResolver.resolvePlaceholder(actualPlaceholder);
+						if (propVal == null) {
+							propVal = defaultValue;
+						}
+					}
+				}
 				if (propVal != null) {
 					// Recursive invocation, parsing placeholders contained in the
 					// previously resolved placeholder value.
 					propVal = parseStringValue(propVal, placeholderResolver, visitedPlaceholders);
 					buf.replace(startIndex, endIndex + this.placeholderSuffix.length(), propVal);
 
-					if (LOGGER.isTraceEnabled()) {
-						LOGGER.trace("Resolved placeholder '" + placeholder + "'");
+					if (logger.isTraceEnabled()) {
+						logger.trace("Resolved placeholder '" + placeholder + "'");
 					}
 
 					startIndex = buf.indexOf(this.placeholderPrefix, startIndex + propVal.length());
@@ -174,19 +187,19 @@ public class PropertyPlaceholderHelper {
 		return -1;
 	}
 
+
 	/**
 	 * Strategy interface used to resolve replacement values for placeholders contained in Strings.
-	 *
 	 * @see PropertyPlaceholderHelper
 	 */
 	public static interface PlaceholderResolver {
 
 		/**
 		 * Resolves the supplied placeholder name into the replacement value.
-		 *
 		 * @param placeholderName the name of the placeholder to resolve.
 		 * @return the replacement value or <code>null</code> if no replacement is to be made.
 		 */
 		String resolvePlaceholder(String placeholderName);
 	}
+
 }

org.springframework.core/src/main/java/org/springframework/util/SystemPropertyUtils.java

 /*
- * Copyright 2002-2008 the original author or authors.
+ * Copyright 2002-2009 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.
@@ -38,18 +38,22 @@ public abstract class SystemPropertyUtils {
 	/** Suffix for system property placeholders: "}" */
 	public static final String PLACEHOLDER_SUFFIX = "}";
 
-	private static final PropertyPlaceholderHelper HELPER = new PropertyPlaceholderHelper(PLACEHOLDER_PREFIX, PLACEHOLDER_SUFFIX);
+	/** Value separator for system property placeholders: "}" */
+	public static final String VALUE_SEPARATOR = ":";
+
+	private static final PropertyPlaceholderHelper helper =
+			new PropertyPlaceholderHelper(PLACEHOLDER_PREFIX, PLACEHOLDER_SUFFIX, VALUE_SEPARATOR, false);
+
+
 	/**
 	 * Resolve ${...} placeholders in the given text, replacing them with corresponding system property values.
-	 *
 	 * @param text the String to resolve
 	 * @return the resolved String
 	 * @see #PLACEHOLDER_PREFIX
 	 * @see #PLACEHOLDER_SUFFIX
 	 */
 	public static String resolvePlaceholders(final String text) {
-		return HELPER.replacePlaceholders(text, new PlaceholderResolver() {
-
+		return helper.replacePlaceholders(text, new PlaceholderResolver() {
 			public String resolvePlaceholder(String placeholderName) {
 				String propVal = null;
 				try {

org.springframework.core/src/test/java/org/springframework/util/PropertyPlaceholderHelperTests.java

@@ -18,10 +18,12 @@ package org.springframework.util;
 
 import java.util.Properties;
 
+import static org.junit.Assert.*;
 import org.junit.Test;
-import static org.junit.Assert.assertEquals;
 
-/** @author Rob Harrop */
+/**
+ * @author Rob Harrop
+ */
 public class PropertyPlaceholderHelperTests {
 
 	private final PropertyPlaceholderHelper helper = new PropertyPlaceholderHelper("${", "}");
@@ -98,7 +100,8 @@ public class PropertyPlaceholderHelperTests {
 		Properties props = new Properties();
 		props.setProperty("foo", "bar");
 
-		PropertyPlaceholderHelper helper = new PropertyPlaceholderHelper("${", "}", false);
+		PropertyPlaceholderHelper helper = new PropertyPlaceholderHelper("${", "}", null, false);
 		assertEquals("foo=bar,bar=${bar}", helper.replacePlaceholders(text, props));
 	}
+
 }

org.springframework.core/src/test/java/org/springframework/util/SystemPropertyUtilsTests.java

@@ -18,33 +18,54 @@ package org.springframework.util;
 
 import java.util.Map;
 
+import static org.junit.Assert.*;
 import org.junit.Test;
-import static org.junit.Assert.assertEquals;
 
-/** @author Rob Harrop */
+/**
+ * @author Rob Harrop
+ * @author Juergen Hoeller
+ */
 public class SystemPropertyUtilsTests {
 
 	@Test
 	public void testReplaceFromSystemProperty() {
 		System.setProperty("test.prop", "bar");
-		String resolved = SystemPropertyUtils.resolvePlaceholders("${test.prop}");
-		assertEquals("bar", resolved);
+		try {
+			String resolved = SystemPropertyUtils.resolvePlaceholders("${test.prop}");
+			assertEquals("bar", resolved);
+		}
+		finally {
+			System.getProperties().remove("test.prop");
+		}
+	}
+
+	@Test
+	public void testReplaceWithDefault() {
+		String resolved = SystemPropertyUtils.resolvePlaceholders("${test.prop:foo}");
+		assertEquals("foo", resolved);
 	}
 
 	@Test
 	public void testRecursiveFromSystemProperty() {
 		System.setProperty("test.prop", "foo=${bar}");
 		System.setProperty("bar", "baz");
-		String resolved = SystemPropertyUtils.resolvePlaceholders("${test.prop}");
-		assertEquals("foo=baz", resolved);
+		try {
+			String resolved = SystemPropertyUtils.resolvePlaceholders("${test.prop}");
+			assertEquals("foo=baz", resolved);
+		}
+		finally {
+			System.getProperties().remove("test.prop");
+			System.getProperties().remove("bar");
+		}
 	}
 
 	@Test
 	public void testReplaceFromEnv() {
 		Map<String,String> env = System.getenv();
-		if(env.containsKey("PATH")) {
+		if (env.containsKey("PATH")) {
 			String text = "${PATH}";
 			assertEquals(env.get("PATH"), SystemPropertyUtils.resolvePlaceholders(text));
 		}
 	}
+
 }