com.edduarte.argus.reader.JsonReader.java Source code

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Here is the source code for com.edduarte.argus.reader.JsonReader.java

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/*
 * Copyright 2014 Ed Duarte
 *
 * 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 com.edduarte.argus.reader;

import com.google.common.collect.ImmutableSet;
import com.google.gson.Gson;
import com.google.gson.JsonArray;
import com.google.gson.JsonElement;
import com.google.gson.JsonObject;
import com.google.gson.JsonPrimitive;
import it.unimi.dsi.lang.MutableString;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;

/**
 * A reader class that supports reading documents in the JSON format.
 *
 * @author Ed Duarte (<a href="mailto:ed@edduarte.com">ed@edduarte.com</a>)
 * @version 1.3.2
 * @since 1.0.0
 */
public class JsonReader implements com.edduarte.argus.reader.Reader {

    private final Gson jsonParser;

    public JsonReader() {
        jsonParser = new Gson();
    }

    @Override
    public MutableString readDocumentContents(InputStream documentStream) throws IOException {
        MutableString sb = new MutableString();
        try (BufferedReader reader = new BufferedReader(new InputStreamReader(documentStream))) {
            for (int c; (c = reader.read()) != -1;) {
                sb.append((char) c);
            }
        }

        JsonElement fullText = jsonParser.fromJson(sb.toString(), JsonElement.class);
        sb.delete(0, sb.length());
        readRecursive(fullText, sb);

        return sb.compact();
    }

    private void readRecursive(JsonElement root, MutableString collector) {
        if (root.isJsonObject()) {
            JsonObject object = (JsonObject) root;
            object.entrySet().forEach(e -> {
                collector.append(e.getKey());
                collector.append(' ');
                readRecursive(e.getValue(), collector);
                collector.append(' ');
            });
        } else if (root.isJsonArray()) {
            JsonArray array = (JsonArray) root;
            array.forEach(child -> {
                readRecursive(child, collector);
                collector.append(' ');
            });
        } else if (root.isJsonPrimitive()) {
            JsonPrimitive primitive = (JsonPrimitive) root;
            collector.append(primitive.getAsString());
            collector.append(' ');
        }
    }

    @Override
    public ImmutableSet<String> getSupportedContentTypes() {
        return ImmutableSet.of("application/json");
    }
}