blast.config.spring.PlaceholderWithDefaultConfigurer.java Source code

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Here is the source code for blast.config.spring.PlaceholderWithDefaultConfigurer.java

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/* 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
 *
 *     http://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 blast.config.spring;

import java.util.Properties;

import org.springframework.beans.factory.InitializingBean;

/**
 * PropertyPlaceholderConfigurer that allows to define inline default values.
 * <p>
 * Example:
 * <pre>
 * &lt;bean class="org.riotfamily.example.HelloWorld"&gt;
 *     &lt;property name="message" value="${hello.message=Hello World}" /&gt;
 * &lt;/bean&gt;
 * </pre>
 * Since Riot 7.0 you can specify <code>null</code> as default value:
 * <pre>
 * &lt;bean class="org.riotfamily.example.HelloWorld"&gt;
 *     &lt;property name="message" value="${hello.message=}" /&gt;
 * &lt;/bean&gt;
 * </pre>
 * Please note the the trailing equals sign. If omitted, the behavior will
 * depend on the setting of the {@link #setIgnoreUnresolvablePlaceholders(boolean) 
 * ignoreUnresolvablePlaceholders} flag.
 *
 * <b>Originally from Riot, at riotfamily.org.  Modified only slightly for more general use.
 * Original code licensed under Apache 2.0; license header kept intact above.</b>
 * 
 */
public class PlaceholderWithDefaultConfigurer extends GroupingPropertiesPlaceholderConfigurer
        implements InitializingBean {

    public static final String DEFAULT_VALUE_SEPARATOR = "=";

    private static final String NULL_DEFAULT = PlaceholderWithDefaultConfigurer.class.getName() + ".NULL_DEFAULT";

    private String valueSeparator = DEFAULT_VALUE_SEPARATOR;

    private String nullValue;

    public void setValueSeparator(String valueSeparator) {
        this.valueSeparator = valueSeparator;
    }

    @Override
    public void setNullValue(String nullValue) {
        super.setNullValue(nullValue);
        this.nullValue = nullValue;
    }

    public void afterPropertiesSet() throws Exception {
        if (nullValue == null) {
            setNullValue(NULL_DEFAULT);
        }
    }

    @Override
    protected String resolvePlaceholder(String placeholder, Properties props, int systemPropertiesMode) {

        String defaultValue = null;
        int i = placeholder.indexOf(valueSeparator);
        if (i != -1) {
            if (i + 1 < placeholder.length()) {
                defaultValue = placeholder.substring(i + 1);
            } else {
                defaultValue = nullValue;
            }
            placeholder = placeholder.substring(0, i);
        }
        String value = super.resolvePlaceholder(placeholder, props, systemPropertiesMode);

        if (value == null) {
            value = defaultValue;
        }

        return value;
    }

}