com.logsniffer.util.value.ConfigInjector.java Source code

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Here is the source code for com.logsniffer.util.value.ConfigInjector.java

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/*******************************************************************************
 * logsniffer, open source tool for viewing, monitoring and analysing log data.
 * Copyright (c) 2015 Scaleborn UG, www.scaleborn.com
 *
 * logsniffer is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * logsniffer is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *******************************************************************************/
package com.logsniffer.util.value;

import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.context.ApplicationContext;
import org.springframework.core.convert.ConversionService;
import org.springframework.util.ReflectionUtils;
import org.springframework.util.ReflectionUtils.FieldCallback;
import org.springframework.util.ReflectionUtils.FieldFilter;

public class ConfigInjector implements BeanPostProcessor {
    private final Logger LOGGER = LoggerFactory.getLogger(getClass());
    @Autowired
    private ConversionService conversionService;

    @Autowired
    private ApplicationContext appCtx;

    private ConfigValueSource source;

    private ConfigValueSource getSource() {
        if (source == null) {
            source = appCtx.getBean(ConfigValueSource.class);
        }
        return source;
    }

    @Override
    public Object postProcessAfterInitialization(final Object bean, final String beanName) throws BeansException {
        return bean;
    }

    @Override
    public Object postProcessBeforeInitialization(final Object bean, final String beanName) throws BeansException {
        ReflectionUtils.doWithFields(bean.getClass(), new FieldCallback() {
            @Override
            public void doWith(final Field field) throws IllegalArgumentException, IllegalAccessException {
                LOGGER.debug("Injecting value={} for bean={}", field.getName(), beanName);
                field.setAccessible(true);
                final String key = field.getAnnotation(Configured.class).value();
                final String defaultValue = field.getAnnotation(Configured.class).defaultValue();
                final Class<?> targetValueType = (Class<?>) ((ParameterizedType) field.getGenericType())
                        .getActualTypeArguments()[0];
                field.set(bean, new ConfigValue<Object>() {
                    private String oldTextValue;
                    private Object oldValue;

                    @Override
                    public Object get() {
                        String textValue = getSource().getValue(key);
                        if (textValue == null) {
                            textValue = defaultValue;
                        }
                        if (oldTextValue != null && oldTextValue.equals(textValue)) {
                            return oldValue;
                        } else {
                            oldValue = conversionService.convert(textValue, targetValueType);
                            oldTextValue = textValue;
                            return oldValue;
                        }
                    }
                });

            }
        }, new FieldFilter() {
            @Override
            public boolean matches(final Field field) {
                return field.getType().equals(ConfigValue.class) && field.isAnnotationPresent(Configured.class);
            }
        });

        return bean;
    }

}