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The MyBatis Guice module is easy-to-use Google Guice bridge for MyBatis sql mapping framework.

There is a newer version: 4.0.0

/**
 *    Copyright 2009-2015 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.
 *    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.mybatis.guice.datasource.helper;

import com.google.inject.Injector;
import com.google.inject.Key;

import javax.inject.Inject;
import javax.inject.Provider;

import static com.google.inject.name.Names.named;

/**
 *
 *
 * @version $Id$
 */
final class KeyResolver implements Provider {

    private final Key key;

    private final String defaultValue;

    private final String toString;

    @Inject
    private Injector injector;

    public KeyResolver(final String key, final String defaultValue) {
        this.key = Key.get(String.class, named(key));
        this.defaultValue = defaultValue;
        toString = "${" + key + "}";
    }

    public void setInjector(Injector injector) {
        this.injector = injector;
    }

    /**
     * {@inheritDoc}
     */
    public String get() {
        try {
            return injector.getInstance(key);
        } catch (Throwable e) {
            if (defaultValue != null) {
                return defaultValue;
            }
            return toString;
        }
    }

    @Override
    public String toString() {
        return toString;
    }

}