io.debezium.document.JacksonWriter.java Source code

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Here is the source code for io.debezium.document.JacksonWriter.java

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/*
 * Copyright Debezium Authors.
 *
 * Licensed under the Apache Software License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
 */
package io.debezium.document;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.io.StringWriter;
import java.io.Writer;

import com.fasterxml.jackson.core.JsonEncoding;
import com.fasterxml.jackson.core.JsonFactory;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.util.DefaultPrettyPrinter;

import io.debezium.annotation.ThreadSafe;

/**
 * A {@link DocumentWriter} and {@link ArrayWriter} that uses the Jackson library to write JSON.
 * 
 * @author Randall Hauch
 */
@ThreadSafe
final class JacksonWriter implements DocumentWriter, ArrayWriter {

    public static final JacksonWriter INSTANCE = new JacksonWriter(false);
    public static final JacksonWriter PRETTY_WRITER = new JacksonWriter(true);

    private static final JsonFactory factory;

    static {
        factory = new JsonFactory();
    }

    private final boolean pretty;

    private JacksonWriter(boolean pretty) {
        this.pretty = pretty;
    }

    @Override
    public void write(Document document, OutputStream jsonStream) throws IOException {
        try (JsonGenerator jsonGenerator = factory.createGenerator(jsonStream)) {
            configure(jsonGenerator);
            writeDocument(document, jsonGenerator);
        }
    }

    @Override
    public void write(Document document, Writer jsonWriter) throws IOException {
        try (JsonGenerator jsonGenerator = factory.createGenerator(jsonWriter)) {
            configure(jsonGenerator);
            writeDocument(document, jsonGenerator);
        }
    }

    @Override
    public String write(Document document) throws IOException {
        StringWriter writer = new StringWriter();
        try (JsonGenerator jsonGenerator = factory.createGenerator(writer)) {
            configure(jsonGenerator);
            writeDocument(document, jsonGenerator);
        }
        return writer.getBuffer().toString();
    }

    @Override
    public byte[] writeAsBytes(Document document) {
        try (ByteArrayOutputStream stream = new ByteArrayOutputStream()) {
            try (JsonGenerator jsonGenerator = factory.createGenerator(stream, JsonEncoding.UTF8)) {
                configure(jsonGenerator);
                writeDocument(document, jsonGenerator);
            }
            return stream.toByteArray();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

    @Override
    public void write(Array array, OutputStream jsonStream) throws IOException {
        try (JsonGenerator jsonGenerator = factory.createGenerator(jsonStream)) {
            configure(jsonGenerator);
            writeArray(array, jsonGenerator);
        }
    }

    @Override
    public void write(Array array, Writer jsonWriter) throws IOException {
        try (JsonGenerator jsonGenerator = factory.createGenerator(jsonWriter)) {
            configure(jsonGenerator);
            writeArray(array, jsonGenerator);
        }
    }

    @Override
    public String write(Array array) throws IOException {
        StringWriter writer = new StringWriter();
        try (JsonGenerator jsonGenerator = factory.createGenerator(writer)) {
            configure(jsonGenerator);
            writeArray(array, jsonGenerator);
        }
        return writer.getBuffer().toString();
    }

    protected void configure(JsonGenerator generator) {
        if (pretty)
            generator.setPrettyPrinter(new DefaultPrettyPrinter());
    }

    protected void writeDocument(Document document, JsonGenerator generator) throws IOException {
        generator.writeStartObject();
        try {
            document.stream().forEach((field) -> {
                try {
                    generator.writeFieldName(field.getName().toString());
                    writeValue(field.getValue(), generator);
                } catch (IOException e) {
                    throw new WritingError(e);
                }
            });
            generator.writeEndObject();
        } catch (WritingError e) {
            throw e.wrapped();
        }
    }

    protected void writeArray(Array array, JsonGenerator generator) throws IOException {
        generator.writeStartArray();
        try {
            array.streamValues().forEach((value) -> {
                try {
                    writeValue(value, generator);
                } catch (IOException e) {
                    throw new WritingError(e);
                }
            });
            generator.writeEndArray();
        } catch (WritingError e) {
            throw e.wrapped();
        }
    }

    protected void writeValue(Value value, JsonGenerator generator) throws IOException {
        switch (value.getType()) {
        case NULL:
            generator.writeNull();
            break;
        case STRING:
            generator.writeString(value.asString());
            break;
        case BOOLEAN:
            generator.writeBoolean(value.asBoolean());
            break;
        case BINARY:
            generator.writeBinary(value.asBytes());
            break;
        case INTEGER:
            generator.writeNumber(value.asInteger());
            break;
        case LONG:
            generator.writeNumber(value.asLong());
            break;
        case FLOAT:
            generator.writeNumber(value.asFloat());
            break;
        case DOUBLE:
            generator.writeNumber(value.asDouble());
            break;
        case BIG_INTEGER:
            generator.writeNumber(value.asBigInteger());
            break;
        case DECIMAL:
            generator.writeNumber(value.asBigDecimal());
            break;
        case DOCUMENT:
            writeDocument(value.asDocument(), generator);
            break;
        case ARRAY:
            writeArray(value.asArray(), generator);
            break;
        }
    }

    protected static final class WritingError extends RuntimeException {
        private static final long serialVersionUID = 1L;
        private final IOException wrapped;

        protected WritingError(IOException wrapped) {
            this.wrapped = wrapped;
        }

        public IOException wrapped() {
            return wrapped;
        }
    }

}