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JSON reader and writer libary
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/**
* Copyright (C) 2014-2021 Philip Helger (www.helger.com)
* philip[at]helger[dot]com
*
* 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.helger.json.serialize;
import java.io.IOException;
import java.io.OutputStream;
import java.io.OutputStreamWriter;
import java.io.Writer;
import java.nio.charset.Charset;
import java.util.Map;
import javax.annotation.Nonnull;
import javax.annotation.WillClose;
import javax.annotation.WillNotClose;
import javax.annotation.concurrent.NotThreadSafe;
import com.helger.commons.ValueEnforcer;
import com.helger.commons.annotation.ReturnsMutableCopy;
import com.helger.commons.io.stream.NonBlockingByteArrayOutputStream;
import com.helger.commons.io.stream.NonBlockingStringWriter;
import com.helger.commons.io.stream.NonClosingOutputStream;
import com.helger.commons.io.stream.StreamHelper;
import com.helger.commons.string.StringHelper;
import com.helger.json.CJson;
import com.helger.json.IJson;
import com.helger.json.IJsonArray;
import com.helger.json.IJsonCollection;
import com.helger.json.IJsonObject;
import com.helger.json.IJsonValue;
import com.helger.json.convert.JsonEscapeHelper;
import com.helger.json.valueserializer.JsonValueSerializerEscaped;
/**
* Convert {@link IJson} objects to a String.
*
* @author Philip Helger
*/
@NotThreadSafe
public class JsonWriter
{
private final IJsonWriterSettings m_aSettings;
public JsonWriter ()
{
this (JsonWriterSettings.DEFAULT_SETTINGS);
}
public JsonWriter (@Nonnull final IJsonWriterSettings aSettings)
{
ValueEnforcer.notNull (aSettings, "Settings");
m_aSettings = aSettings.getClone ();
}
/**
* @return A clone of the JSON writer settings to be used. Never
* null.
*/
@Nonnull
@ReturnsMutableCopy
public IJsonWriterSettings getSettings ()
{
return m_aSettings.getClone ();
}
private void _writeToWriter (@Nonnull final IJson aJson,
@Nonnull @WillNotClose final Writer aWriter,
final int nIndentLevel) throws IOException
{
ValueEnforcer.notNull (aJson, "Json");
if (aJson.isValue ())
{
// Simple value
((IJsonValue) aJson).appendAsJsonString (aWriter);
}
else
{
// Complex (array or object)
final boolean bIsIndentEnabled = m_aSettings.isIdentEnabled () && ((IJsonCollection) aJson).isNotEmpty ();
final String sSingleIndent = m_aSettings.getIndentString ();
final String sIndentString = bIsIndentEnabled ? StringHelper.getRepeated (sSingleIndent, nIndentLevel) : "";
final String sNestedIndentString = bIsIndentEnabled ? sIndentString + sSingleIndent : "";
final String sNewlineString = bIsIndentEnabled ? m_aSettings.getNewlineString () : "";
final boolean bQuoteNames = m_aSettings.isQuoteNames ();
if (aJson.isArray ())
{
aWriter.write (CJson.ARRAY_START);
if (bIsIndentEnabled)
aWriter.write (sNewlineString);
boolean bFirstChild = true;
for (final IJson aChild : (IJsonArray) aJson)
{
if (bFirstChild)
bFirstChild = false;
else
{
aWriter.write (CJson.ITEM_SEPARATOR);
if (bIsIndentEnabled)
aWriter.write (sNewlineString);
}
if (bIsIndentEnabled)
aWriter.write (sNestedIndentString);
_writeToWriter (aChild, aWriter, nIndentLevel + 1);
}
// Newline after the last entry
if (bIsIndentEnabled)
{
aWriter.write (m_aSettings.getNewlineString ());
aWriter.write (sIndentString);
}
aWriter.write (CJson.ARRAY_END);
}
else
{
// Must be an object
aWriter.write (CJson.OBJECT_START);
if (bIsIndentEnabled)
aWriter.write (sNewlineString);
boolean bFirstChild = true;
for (final Map.Entry aEntry : (IJsonObject) aJson)
{
if (bFirstChild)
bFirstChild = false;
else
{
aWriter.write (CJson.ITEM_SEPARATOR);
if (bIsIndentEnabled)
aWriter.write (sNewlineString);
}
if (bIsIndentEnabled)
aWriter.write (sNestedIndentString);
// Object name
if (bQuoteNames)
JsonValueSerializerEscaped.appendEscapedJsonString (aEntry.getKey (), aWriter);
else
JsonEscapeHelper.jsonEscapeToWriter (aEntry.getKey (), aWriter);
// Name value separator
aWriter.write (CJson.NAME_VALUE_SEPARATOR);
// Object value
_writeToWriter (aEntry.getValue (), aWriter, nIndentLevel + 1);
}
// Newline after the last entry
if (bIsIndentEnabled)
{
aWriter.write (sNewlineString);
aWriter.write (sIndentString);
}
aWriter.write (CJson.OBJECT_END);
}
}
}
public void writeToWriter (@Nonnull final IJson aJson, @Nonnull @WillNotClose final Writer aWriter) throws IOException
{
ValueEnforcer.notNull (aJson, "Json");
ValueEnforcer.notNull (aWriter, "Writer");
_writeToWriter (aJson, aWriter, 0);
if (m_aSettings.isWriteNewlineAtEnd ())
aWriter.write (m_aSettings.getNewlineString ());
aWriter.flush ();
}
public void writeToWriterAndClose (@Nonnull final IJson aJson, @Nonnull @WillClose final Writer aWriter) throws IOException
{
ValueEnforcer.notNull (aJson, "Json");
ValueEnforcer.notNull (aWriter, "Writer");
try
{
writeToWriter (aJson, aWriter);
}
finally
{
StreamHelper.close (aWriter);
}
}
@Nonnull
public String writeAsString (@Nonnull final IJson aJson)
{
ValueEnforcer.notNull (aJson, "Json");
try (final NonBlockingStringWriter aWriter = new NonBlockingStringWriter (1024))
{
writeToWriter (aJson, aWriter);
return aWriter.getAsString ();
}
catch (final IOException ex)
{
throw new IllegalStateException ("NonBlockingStringWriter should never throw IOException!", ex);
}
}
/**
* Write the JSON to an OutputStream using the provided Charset, and leave the
* OutputStream open.
*
* @param aJson
* The JSON to be written. May not be null.
* @param aOS
* The OutputStream to write to. May not be null.
* @param aCharset
* The character set to be used. May not be null.
* @throws IOException
* On IO error
* @since 9.4.0
*/
public void writeToStream (@Nonnull final IJson aJson,
@Nonnull @WillNotClose final OutputStream aOS,
@Nonnull final Charset aCharset) throws IOException
{
ValueEnforcer.notNull (aJson, "Json");
ValueEnforcer.notNull (aOS, "OutputStream");
ValueEnforcer.notNull (aCharset, "Charset");
// Ensure OutputStream stays open
try (final Writer aWriter = new OutputStreamWriter (new NonClosingOutputStream (aOS), aCharset))
{
writeToWriter (aJson, aWriter);
}
}
/**
* Write the JSON to an OutputStream using the provided Charset, and close the
* OutputStream afterwards.
*
* @param aJson
* The JSON to be written. May not be null.
* @param aOS
* The OutputStream to write to. May not be null.
* @param aCharset
* The character set to be used. May not be null.
* @throws IOException
* On IO error
* @since 9.4.0
*/
public void writeToStreamAndClose (@Nonnull final IJson aJson,
@Nonnull @WillClose final OutputStream aOS,
@Nonnull final Charset aCharset) throws IOException
{
ValueEnforcer.notNull (aJson, "Json");
ValueEnforcer.notNull (aOS, "OutputStream");
ValueEnforcer.notNull (aCharset, "Charset");
// Ensure OutputStream gets closed as well
try (final Writer aWriter = new OutputStreamWriter (aOS, aCharset))
{
writeToWriter (aJson, aWriter);
}
}
/**
* Write the JSON to an byte array using the provided Charset.
*
* @param aJson
* The JSON to be written. May not be null.
* @param aCharset
* The character set to be used. May not be null.
* @return The created byte array and never null.
* @since 9.4.0
*/
@Nonnull
public byte [] writeAsByteArray (@Nonnull final IJson aJson, @Nonnull final Charset aCharset)
{
ValueEnforcer.notNull (aJson, "Json");
try (final NonBlockingByteArrayOutputStream aBAOS = new NonBlockingByteArrayOutputStream (1024))
{
writeToStream (aJson, aBAOS, aCharset);
return aBAOS.getBufferOrCopy ();
}
catch (final IOException ex)
{
throw new IllegalStateException ("NonBlockingByteArrayOutputStream should never throw IOException!", ex);
}
}
}