com.google.openrtb.json.OpenRtbJsonExtWriter.java Source code

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Here is the source code for com.google.openrtb.json.OpenRtbJsonExtWriter.java

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/*
 * Copyright 2014 Google Inc. All Rights Reserved.
 *
 * 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.google.openrtb.json;

import static com.google.common.base.Preconditions.checkNotNull;

import com.fasterxml.jackson.core.JsonGenerator;
import java.io.IOException;
import java.util.List;

/**
 * A serialization extension, can add children of "ext" fields.
 *
 * <p>Implementations of this interface have to be threadsafe.
 *
 * @param <T> Type of extension field
 */
public abstract class OpenRtbJsonExtWriter<T> {
    private final String rootName;
    private final boolean isJsonObject;

    /**
     * Use this constructor for writers of regular extensions.
     */
    protected OpenRtbJsonExtWriter() {
        this.rootName = null;
        this.isJsonObject = false;
    }

    /**
     * Use this constructor for writers of repeated extensions.
     *
     * @param rootName Name for the "root" entity: the field that holds an array or the object
     * @param isJsonObject {@code true} if the extension value is serialized to a JSON object
     */
    protected OpenRtbJsonExtWriter(String rootName, boolean isJsonObject) {
        this.rootName = checkNotNull(rootName);
        this.isJsonObject = isJsonObject;
    }

    protected final void writeRepeated(List<T> extList, JsonGenerator gen) throws IOException {
        gen.writeArrayFieldStart(rootName);
        for (T ext : extList) {
            if (isJsonObject) {
                gen.writeStartObject();
            }
            write(ext, gen);
            if (isJsonObject) {
                gen.writeEndObject();
            }
        }
        gen.writeEndArray();
    }

    protected final void writeSingle(T value, JsonGenerator gen) throws IOException {
        if (isJsonObject) {
            gen.writeObjectFieldStart(rootName);
        }
        write(value, gen);
        if (isJsonObject) {
            gen.writeEndObject();
        }
    }

    /**
     * Write the fields of an extension value.
     *
     * @param value The extension value (scalar field)
     * @param gen The JSON generator
     * @throws IOException any serialization error
     */
    protected abstract void write(T value, JsonGenerator gen) throws IOException;

    @Override
    public String toString() {
        return getClass().getName() + (isJsonObject ? " JSON=object" : " JSON=scalar")
                + (rootName == null ? " regular" : " repeated:" + rootName);
    }
}