software.amazon.awssdk.protocols.jsoncore.JsonWriter Maven / Gradle / Ivy
/*
* Copyright Amazon.com, Inc. or its affiliates. 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.
* A copy of the License is located at
*
* http://aws.amazon.com/apache2.0
*
* or in the "license" file accompanying this file. This file 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 software.amazon.awssdk.protocols.jsoncore;
import static software.amazon.awssdk.protocols.jsoncore.JsonNodeParser.DEFAULT_JSON_FACTORY;
import static software.amazon.awssdk.utils.DateUtils.formatUnixTimestampInstant;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.time.Instant;
import software.amazon.awssdk.annotations.SdkProtectedApi;
import software.amazon.awssdk.thirdparty.jackson.core.JsonFactory;
import software.amazon.awssdk.thirdparty.jackson.core.JsonGenerator;
import software.amazon.awssdk.utils.BinaryUtils;
import software.amazon.awssdk.utils.FunctionalUtils;
import software.amazon.awssdk.utils.SdkAutoCloseable;
/**
* Thin wrapper around Jackson's JSON generator.
*/
@SdkProtectedApi
public class JsonWriter implements SdkAutoCloseable {
private static final int DEFAULT_BUFFER_SIZE = 1024;
private final ByteArrayOutputStream baos;
private final JsonGenerator generator;
private JsonWriter(Builder builder) {
JsonGeneratorFactory jsonGeneratorFactory = builder.jsonGeneratorFactory != null
? builder.jsonGeneratorFactory
: DEFAULT_JSON_FACTORY::createGenerator;
try {
baos = new ByteArrayOutputStream(DEFAULT_BUFFER_SIZE);
generator = jsonGeneratorFactory.createGenerator(baos);
} catch (IOException e) {
throw new JsonGenerationException(e);
}
}
public static JsonWriter create() {
return builder().build();
}
public static JsonWriter.Builder builder() {
return new Builder();
}
public JsonWriter writeStartArray() {
return unsafeWrite(generator::writeStartArray);
}
public JsonWriter writeEndArray() {
return unsafeWrite(generator::writeEndArray);
}
public JsonWriter writeNull() {
return unsafeWrite(generator::writeNull);
}
public JsonWriter writeStartObject() {
return unsafeWrite(generator::writeStartObject);
}
public JsonWriter writeEndObject() {
return unsafeWrite(generator::writeEndObject);
}
public JsonWriter writeFieldName(String fieldName) {
return unsafeWrite(() -> generator.writeFieldName(fieldName));
}
public JsonWriter writeValue(String val) {
return unsafeWrite(() -> generator.writeString(val));
}
public JsonWriter writeValue(boolean bool) {
return unsafeWrite(() -> generator.writeBoolean(bool));
}
public JsonWriter writeValue(long val) {
return unsafeWrite(() -> generator.writeNumber(val));
}
public JsonWriter writeValue(double val) {
return unsafeWrite(() -> generator.writeNumber(val));
}
public JsonWriter writeValue(float val) {
return unsafeWrite(() -> generator.writeNumber(val));
}
public JsonWriter writeValue(short val) {
return unsafeWrite(() -> generator.writeNumber(val));
}
public JsonWriter writeValue(int val) {
return unsafeWrite(() -> generator.writeNumber(val));
}
public JsonWriter writeValue(ByteBuffer bytes) {
return unsafeWrite(() -> generator.writeBinary(BinaryUtils.copyBytesFrom(bytes)));
}
public JsonWriter writeValue(Instant instant) {
return unsafeWrite(() -> generator.writeNumber(formatUnixTimestampInstant(instant)));
}
public JsonWriter writeValue(BigDecimal value) {
return unsafeWrite(() -> generator.writeString(value.toString()));
}
public JsonWriter writeValue(BigInteger value) {
return unsafeWrite(() -> generator.writeNumber(value));
}
public JsonWriter writeNumber(String number) {
return unsafeWrite(() -> generator.writeNumber(number));
}
/**
* Closes the generator and flushes to write. Must be called when finished writing JSON
* content.
*/
@Override
public void close() {
try {
generator.close();
} catch (IOException e) {
throw new JsonGenerationException(e);
}
}
/**
* Get the JSON content as a UTF-8 encoded byte array. It is recommended to hold onto the array
* reference rather then making repeated calls to this method as a new array will be created
* each time.
*
* @return Array of UTF-8 encoded bytes that make up the generated JSON.
*/
public byte[] getBytes() {
close();
return baos.toByteArray();
}
private JsonWriter unsafeWrite(FunctionalUtils.UnsafeRunnable r) {
try {
r.run();
} catch (Exception e) {
throw new JsonGenerationException(e);
}
return this;
}
/**
* A builder for configuring and creating {@link JsonWriter}. Created via {@link #builder()}.
*/
public static final class Builder {
private JsonGeneratorFactory jsonGeneratorFactory;
private Builder() {
}
/**
* The {@link JsonFactory} implementation to be used when parsing the input. This allows JSON extensions like CBOR or
* Ion to be supported.
*
* It's highly recommended to use a shared {@code JsonFactory} where possible, so they should be stored statically:
* http://wiki.fasterxml.com/JacksonBestPracticesPerformance
*
*
By default, this is {@link JsonNodeParser#DEFAULT_JSON_FACTORY}.
*
*
Setting this value will also override any values set via {@link #jsonGeneratorFactory}.
*/
public JsonWriter.Builder jsonFactory(JsonFactory jsonFactory) {
jsonGeneratorFactory(jsonFactory::createGenerator);
return this;
}
/**
* A factory for {@link JsonGenerator}s based on an {@link OutputStream}. This allows custom JSON generator
* configuration, like pretty-printing output.
*
*
It's highly recommended to use a shared {@code JsonFactory} within this generator factory, where possible, so they
* should be stored statically: http://wiki.fasterxml.com/JacksonBestPracticesPerformance
*
*
By default, this delegates to {@link JsonNodeParser#DEFAULT_JSON_FACTORY} to create the generator.
*
*
Setting this value will also override any values set via {@link #jsonFactory}.
*/
public JsonWriter.Builder jsonGeneratorFactory(JsonGeneratorFactory jsonGeneratorFactory) {
this.jsonGeneratorFactory = jsonGeneratorFactory;
return this;
}
/**
* Build a {@link JsonNodeParser} based on the current configuration of this builder.
*/
public JsonWriter build() {
return new JsonWriter(this);
}
}
/**
* Generate a {@link JsonGenerator} for a {@link OutputStream}. This will get called once for each "write" call.
*/
@FunctionalInterface
public interface JsonGeneratorFactory {
JsonGenerator createGenerator(OutputStream outputStream) throws IOException;
}
/**
* Indicates an issue writing JSON content.
*/
public static class JsonGenerationException extends RuntimeException {
public JsonGenerationException(Throwable t) {
super(t);
}
}
}