BridgePropertyPlaceholderConfigurer.java

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.camel.spring.spi;

import java.util.Collections;
import java.util.List;
import java.util.Properties;

import org.apache.camel.CamelContext;
import org.apache.camel.component.properties.AugmentedPropertyNameAwarePropertiesParser;
import org.apache.camel.component.properties.PropertiesLocation;
import org.apache.camel.component.properties.PropertiesParser;
import org.apache.camel.component.properties.PropertiesResolver;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;
import org.springframework.core.Constants;
import org.springframework.util.PropertyPlaceholderHelper;

/**
 * A {@link PropertyPlaceholderConfigurer} that bridges Camel's <a href="http://camel.apache.org/using-propertyplaceholder.html">
 * property placeholder</a> with the Spring property placeholder mechanism.
 */
public class BridgePropertyPlaceholderConfigurer extends PropertyPlaceholderConfigurer implements PropertiesResolver, AugmentedPropertyNameAwarePropertiesParser {

    // NOTE: this class must be in the spi package as if its in the root package, then Spring fails to parse the XML
    // files due some weird spring issue. But that is okay as having this class in the spi package is fine anyway.

    private final Properties properties = new Properties();
    private PropertiesResolver resolver;
    private PropertiesParser parser;
    private String id;
    private PropertyPlaceholderHelper helper;

    // to support both Spring 3.0 / 3.1+ we need to keep track of these as they have private modified in Spring 3.0
    private String configuredPlaceholderPrefix;
    private String configuredPlaceholderSuffix;
    private String configuredValueSeparator;
    private Boolean configuredIgnoreUnresolvablePlaceholders;
    private int systemPropertiesMode = SYSTEM_PROPERTIES_MODE_FALLBACK;
    private Boolean ignoreResourceNotFound;

    public int getSystemPropertiesMode() {
        return systemPropertiesMode;
    }

    @Override
    protected void processProperties(ConfigurableListableBeanFactory beanFactoryToProcess, Properties props) throws BeansException {
        super.processProperties(beanFactoryToProcess, props);
        // store all the spring properties so we can refer to them later
        properties.putAll(props);
        // create helper
        helper = new PropertyPlaceholderHelper(
                configuredPlaceholderPrefix != null ? configuredPlaceholderPrefix : DEFAULT_PLACEHOLDER_PREFIX,
                configuredPlaceholderSuffix != null ? configuredPlaceholderSuffix : DEFAULT_PLACEHOLDER_SUFFIX,
                configuredValueSeparator != null ? configuredValueSeparator : DEFAULT_VALUE_SEPARATOR,
                configuredIgnoreUnresolvablePlaceholders != null ? configuredIgnoreUnresolvablePlaceholders : false);
    }

    @Override
    public void setBeanName(String beanName) {
        this.id = beanName;
        super.setBeanName(beanName);
    }

    @Override
    public void setSystemPropertiesModeName(String constantName) throws IllegalArgumentException {
        super.setSystemPropertiesModeName(constantName);
        Constants constants = new Constants(PropertyPlaceholderConfigurer.class);
        this.systemPropertiesMode = constants.asNumber(constantName).intValue();
    }

    @Override
    public void setSystemPropertiesMode(int systemPropertiesMode) {
        super.setSystemPropertiesMode(systemPropertiesMode);
        this.systemPropertiesMode = systemPropertiesMode;
    }

    @Override
    public void setPlaceholderPrefix(String placeholderPrefix) {
        super.setPlaceholderPrefix(placeholderPrefix);
        this.configuredPlaceholderPrefix = placeholderPrefix;
    }

    @Override
    public void setPlaceholderSuffix(String placeholderSuffix) {
        super.setPlaceholderSuffix(placeholderSuffix);
        this.configuredPlaceholderSuffix = placeholderSuffix;
    }

    @Override
    public void setValueSeparator(String valueSeparator) {
        super.setValueSeparator(valueSeparator);
        this.configuredValueSeparator = valueSeparator;
    }

    @Override
    public void setIgnoreUnresolvablePlaceholders(boolean ignoreUnresolvablePlaceholders) {
        super.setIgnoreUnresolvablePlaceholders(ignoreUnresolvablePlaceholders);
        this.configuredIgnoreUnresolvablePlaceholders = ignoreUnresolvablePlaceholders;
    }
    
    @Override
    public void setIgnoreResourceNotFound(boolean ignoreResourceNotFound) {
        super.setIgnoreResourceNotFound(ignoreResourceNotFound);
        this.ignoreResourceNotFound = ignoreResourceNotFound;
    }
    
    @Override
    protected String resolvePlaceholder(String placeholder, Properties props) {
        String value = props.getProperty(placeholder);
        if (parser != null) {
            // Just apply the parser to the place holder value to avoid configuring the other placeholder configure twice for the inside and outside camel context
            return parser.parseProperty(placeholder, value, props);
        } else {
            return value;
        }
    }

    @Override
    public Properties resolveProperties(CamelContext context, boolean ignoreMissingLocation, List<PropertiesLocation> locations) throws Exception {
        // return the spring properties, if it
        Properties answer = new Properties();
        for (PropertiesLocation location : locations) {
            if ("ref".equals(location.getResolver()) && id.equals(location.getPath())) {
                answer.putAll(properties);
            } else if (resolver != null) {
                boolean flag = ignoreMissingLocation;
                // Override the setting by using ignoreResourceNotFound
                if (ignoreResourceNotFound != null) {
                    flag = ignoreResourceNotFound;
                }
                Properties p = resolver.resolveProperties(context, flag, Collections.singletonList(location));
                if (p != null) {
                    answer.putAll(p);
                }
            }
        }
        // must not return null
        return answer;
    }

    @Override
    public String parseUri(String text, Properties properties, String prefixToken, String suffixToken,
                           String propertyPrefix, String propertySuffix, boolean fallbackToUnaugmentedProperty, boolean defaultFallbackEnabled) throws IllegalArgumentException {

        // first let Camel parse the text as it may contain Camel placeholders
        String answer;
        if (parser instanceof AugmentedPropertyNameAwarePropertiesParser) {
            answer = ((AugmentedPropertyNameAwarePropertiesParser) parser).parseUri(text, properties, prefixToken, suffixToken,
                    propertyPrefix, propertySuffix, fallbackToUnaugmentedProperty, defaultFallbackEnabled);
        } else {
            answer = parser.parseUri(text, properties, prefixToken, suffixToken);
        }

        // then let Spring parse it to resolve any Spring placeholders
        if (answer != null) {
            answer = springResolvePlaceholders(answer, properties);
        } else {
            answer = springResolvePlaceholders(text, properties);
        }
        return answer;
    }

    @Override
    public String parseUri(String text, Properties properties, String prefixToken, String suffixToken) throws IllegalArgumentException {
        String answer = parser.parseUri(text, properties, prefixToken, suffixToken);
        if (answer != null) {
            answer = springResolvePlaceholders(answer, properties);
        } else {
            answer = springResolvePlaceholders(text, properties);
        }
        return answer;
    }

    @Override
    public String parseProperty(String key, String value, Properties properties) {
        String answer = parser.parseProperty(key, value, properties);
        if (answer != null) {
            answer = springResolvePlaceholders(answer, properties);
        } else {
            answer = springResolvePlaceholders(value, properties);
        }
        return answer;
    }

    /**
     * Resolves the placeholders using Spring's property placeholder functionality.
     *
     * @param text   the text which may contain spring placeholders
     * @param properties the properties
     * @return the parsed text with replaced placeholders, or the original text as is
     */
    protected String springResolvePlaceholders(String text, Properties properties) {
        return helper.replacePlaceholders(text, new BridgePropertyPlaceholderResolver(properties));
    }

    public void setResolver(PropertiesResolver resolver) {
        this.resolver = resolver;
    }

    public void setParser(PropertiesParser parser) {
        if (this.parser != null) {
            // use a bridge if there is already a parser configured
            this.parser = new BridgePropertiesParser(this.parser, parser);
        } else {
            this.parser = parser;
        }
    }

    private class BridgePropertyPlaceholderResolver implements PropertyPlaceholderHelper.PlaceholderResolver {

        private final Properties properties;

        BridgePropertyPlaceholderResolver(Properties properties) {
            this.properties = properties;
        }

        public String resolvePlaceholder(String placeholderName) {
            String propVal = null;
            if (systemPropertiesMode == SYSTEM_PROPERTIES_MODE_OVERRIDE) {
                propVal = resolveSystemProperty(placeholderName);
            }
            if (propVal == null) {
                propVal = (String) properties.get(placeholderName);
            }
            if (propVal == null && systemPropertiesMode == SYSTEM_PROPERTIES_MODE_FALLBACK) {
                propVal = resolveSystemProperty(placeholderName);
            }
            return propVal;
        }
    }

    private final class BridgePropertiesParser implements PropertiesParser {

        private final PropertiesParser delegate;
        private final PropertiesParser parser;

        private BridgePropertiesParser(PropertiesParser delegate, PropertiesParser parser) {
            this.delegate = delegate;
            this.parser = parser;
        }

        @Override
        public String parseUri(String text, Properties properties, String prefixToken, String suffixToken) throws IllegalArgumentException {
            String answer = null;
            if (delegate != null) {
                answer = delegate.parseUri(text, properties, prefixToken, suffixToken);
            }
            if (answer != null) {
                text = answer;
            }
            return parser.parseUri(text, properties, prefixToken, suffixToken);
        }

        @Override
        public String parseProperty(String key, String value, Properties properties) {
            String answer = null;
            if (delegate != null) {
                answer = delegate.parseProperty(key, value, properties);
            }
            if (answer != null) {
                value = answer;
            }
            return parser.parseProperty(key, value, properties);
        }
    }

}