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/* |
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* Copyright 2002-2009 the original author or authors. |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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package org.springframework.util; |
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import java.util.Properties; |
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/** |
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* Utility class for working with Strings that have placeholder values in them. A placeholder takes the form |
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* <code>${name}</code>. Using <code>PropertyPlaceholderUtils</code> these placeholders can be substituted for |
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* user-supplied values. <p> Values for substitution can be supplied using a {@link Properties} instance or using a |
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* {@link PlaceholderResolver}. |
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* |
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* @author Juergen Hoeller |
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* @author Rob Harrop |
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* @since 3.0 |
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*/ |
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public class PropertyPlaceholderUtils { |
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/** Prefix for property placeholders: "${" */ |
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public static final String PLACEHOLDER_PREFIX = "${"; |
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/** Suffix for property placeholders: "}" */ |
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public static final String PLACEHOLDER_SUFFIX = "}"; |
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/** |
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* Replaces all placeholders of format <code>${name}</code> with the corresponding property from the supplied {@link |
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* Properties}. |
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* |
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* @param value the value containing the placeholders to be replaced. |
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* @param properties the <code>Properties</code> to use for replacement. |
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* @return the supplied value with placeholders replaced inline. |
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*/ |
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public static String replacePlaceholders(String value, final Properties properties) { |
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Assert.notNull(properties, "Argument 'properties' must not be null."); |
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return replacePlaceholders(value, new PlaceholderResolver() { |
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public String resolvePlaceholder(String placeholderName) { |
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return properties.getProperty(placeholderName); |
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} |
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}); |
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} |
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/** |
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* Replaces all placeholders of format <code>${name}</code> with the value returned from the supplied {@link |
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* PlaceholderResolver}. |
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* |
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* @param value the value containing the placeholders to be replaced. |
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* @param placeholderResolver the <code>PlaceholderResolver</code> to use for replacement. |
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* @return the supplied value with placeholders replaced inline. |
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*/ |
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public static String replacePlaceholders(String value, PlaceholderResolver placeholderResolver) { |
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StringBuilder result = new StringBuilder(value); |
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int startIndex = result.indexOf(PLACEHOLDER_PREFIX); |
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while (startIndex != -1) { |
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int endIndex = result.indexOf(PLACEHOLDER_SUFFIX, startIndex + PLACEHOLDER_PREFIX.length()); |
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if (endIndex != -1) { |
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String placeholder = result.substring(startIndex + PLACEHOLDER_PREFIX.length(), endIndex); |
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int nextIndex = endIndex + PLACEHOLDER_SUFFIX.length(); |
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String propVal = placeholderResolver.resolvePlaceholder(placeholder); |
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if (propVal != null) { |
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result.replace(startIndex, endIndex + PLACEHOLDER_SUFFIX.length(), propVal); |
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nextIndex = startIndex + propVal.length(); |
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} |
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startIndex = result.indexOf(PLACEHOLDER_PREFIX, nextIndex); |
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} |
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else { |
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startIndex = -1; |
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} |
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} |
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return result.toString(); |
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} |
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/** |
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* Strategy interface used to resolve replacement values for placeholders contained in Strings. |
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* |
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* @see org.springframework.util.PropertyPlaceholderUtils |
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*/ |
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public static interface PlaceholderResolver { |
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/** |
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* Resolves the supplied placeholder name into the replacement value. |
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* |
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* @param placeholderName the name of the placeholder to resolve. |
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* @return the replacement value or <code>null</code> if no replacement is to be made. |
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*/ |
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String resolvePlaceholder(String placeholderName); |
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} |
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} |
@ -0,0 +1,72 @@ |
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/* |
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* Copyright 2002-2009 the original author or authors. |
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* |
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* Licensed under the Apache License, Version 2.0 (the "License"); |
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* you may not use this file except in compliance with the License. |
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* You may obtain a copy of the License at |
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* |
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* http://www.apache.org/licenses/LICENSE-2.0
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* |
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* Unless required by applicable law or agreed to in writing, software |
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* distributed under the License is distributed on an "AS IS" BASIS, |
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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* See the License for the specific language governing permissions and |
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* limitations under the License. |
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*/ |
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package org.springframework.util; |
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import java.util.Properties; |
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import org.junit.Test; |
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import static org.junit.Assert.assertEquals; |
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/** @author Rob Harrop */ |
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public class PropertyPlaceholderUtilsTests { |
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@Test |
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public void testWithProperties() { |
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String text = "foo=${foo}"; |
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Properties props = new Properties(); |
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props.setProperty("foo", "bar"); |
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assertEquals("foo=bar", PropertyPlaceholderUtils.replacePlaceholders(text, props)); |
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} |
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@Test |
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public void testWithMultipleProperties() { |
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String text = "foo=${foo},bar=${bar}"; |
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Properties props = new Properties(); |
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props.setProperty("foo", "bar"); |
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props.setProperty("bar", "baz"); |
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assertEquals("foo=bar,bar=baz", PropertyPlaceholderUtils.replacePlaceholders(text, props)); |
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} |
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@Test |
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public void testWithResolver() { |
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String text = "foo=${foo}"; |
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assertEquals("foo=bar", |
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PropertyPlaceholderUtils.replacePlaceholders(text, new PropertyPlaceholderUtils.PlaceholderResolver() { |
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public String resolvePlaceholder(String placeholderName) { |
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if ("foo".equals(placeholderName)) { |
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return "bar"; |
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} |
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else { |
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return null; |
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} |
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} |
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})); |
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} |
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@Test |
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public void testUnresolvedPlaceholderIsIgnored() { |
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String text = "foo=${foo},bar=${bar}"; |
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Properties props = new Properties(); |
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props.setProperty("foo", "bar"); |
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assertEquals("foo=bar,bar=${bar}", PropertyPlaceholderUtils.replacePlaceholders(text, props)); |
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} |
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} |
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