JsonPropertySourceLoader.java

/*
 * Copyright 2017-2020 original 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
 *
 * https://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 io.micronaut.jackson.core.env;

import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonParser;
import io.micronaut.context.env.AbstractPropertySourceLoader;
import io.micronaut.core.annotation.Experimental;
import io.micronaut.jackson.core.tree.JsonNodeTreeCodec;
import io.micronaut.json.tree.JsonNode;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.LinkedHashMap;
import java.util.Map;
import java.util.Set;

/**
 * <p>A {@link io.micronaut.context.env.PropertySourceLoader} that reads {@code application.json} files if they exist.</p>
 *
 * @author Graeme Rocher
 * @since 1.0
 */
@Experimental
public class JsonPropertySourceLoader extends AbstractPropertySourceLoader {

    /**
     * File extension for property source loader.
     */
    public static final String FILE_EXTENSION = "json";

    public JsonPropertySourceLoader() {
    }

    public JsonPropertySourceLoader(boolean logEnabled) {
        super(logEnabled);
    }

    @Override
    public Set<String> getExtensions() {
        return Collections.singleton(FILE_EXTENSION);
    }

    @Override
    protected void processInput(String name, InputStream input, Map<String, Object> finalMap) throws IOException {
        Map<String, Object> map = readJsonAsMap(input);
        processMap(finalMap, map, "");
    }

    /**
     * @param input The input stream
     * @return map representation of the json
     * @throws IOException If the input stream doesn't exist
     */
    @SuppressWarnings("unchecked")
    protected Map<String, Object> readJsonAsMap(InputStream input) throws IOException {
        return (Map<String, Object>) unwrap(readJsonAsObject(input));
    }

    private JsonNode readJsonAsObject(InputStream input) throws IOException {
        try (JsonParser parser = new JsonFactory().createParser(input)) {
            return JsonNodeTreeCodec.getInstance().readTree(parser);
        }
    }

    private Object unwrap(JsonNode value) {
        if (value.isNumber()) {
            return value.getNumberValue();
        } else if (value.isNull()) {
            return null;
        } else if (value.isBoolean()) {
            return value.getBooleanValue();
        } else if (value.isArray()) {
            var unwrapped = new ArrayList<>();
            value.values().forEach(v -> unwrapped.add(unwrap(v)));
            return unwrapped;
        } else if (value.isObject()) {
            var unwrapped = new LinkedHashMap<String, Object>();
            value.entries().forEach(e -> unwrapped.put(e.getKey(), unwrap(e.getValue())));
            return unwrapped;
        } else {
            return value.getStringValue();
        }
    }
}