ConfigReader.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.tika.config;

import java.io.IOException;

import org.apache.tika.parser.ParseContext;

/**
 * Reads JSON configuration on behalf of tika-core, which has no JSON library of its own.
 * tika-serialization provides the one implementation: through {@code META-INF/services} on a
 * classpath, or as a service in OSGi.
 *
 * @since Apache Tika 4.2
 */
public interface ConfigReader {

    /**
     * Deserializes {@code json}; untrusted JSON may not set an {@link OperatorOnly} property.
     */
    <T> T readConfig(String json, Class<T> configClass, boolean trusted) throws Exception;

    /**
     * Implements {@link ParseContextConfig#getConfig} once the context holds JSON for the key.
     */
    <T> T getConfig(ParseContext context, String configKey, Class<T> configClass, T defaultConfig)
            throws IOException;

    /**
     * @return the reader, or null if tika-serialization is absent
     * @throws IllegalStateException if more than one reader is available
     */
    static ConfigReader find() {
        return ConfigReaderLookup.find();
    }
}