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com.fasterxml.jackson.databind.SequenceWriter Maven / Gradle / Ivy
General data-binding functionality for Jackson: works on core streaming API
package com.fasterxml.jackson.databind;
import java.io.Closeable;
import java.io.IOException;
import java.util.Collection;
import com.fasterxml.jackson.core.*;
import com.fasterxml.jackson.databind.jsontype.TypeSerializer;
import com.fasterxml.jackson.databind.ser.DefaultSerializerProvider;
import com.fasterxml.jackson.databind.ser.impl.PropertySerializerMap;
import com.fasterxml.jackson.databind.ser.impl.TypeWrappedSerializer;
/**
* Writer class similar to {@link ObjectWriter}, except that it can be used
* for writing sequences of values, not just a single value.
* The main use case is in writing very long sequences, or sequences where
* values are incrementally produced; cases where it would be impractical
* or at least inconvenient to construct a wrapper container around values
* (or where no JSON array is desired around values).
*
* Differences from {@link ObjectWriter} include:
*
* Instances of {@link SequenceWriter} are stateful, and not thread-safe:
* if sharing, external synchronization must be used.
* Explicit {@link #close} is needed after all values have been written
* ({@link ObjectWriter} can auto-close after individual value writes)
*
*
* @since 2.5
*/
public class SequenceWriter
implements Versioned, java.io.Closeable, java.io.Flushable
{
/*
/**********************************************************
/* Configuration
/**********************************************************
*/
protected final DefaultSerializerProvider _provider;
protected final SerializationConfig _config;
protected final JsonGenerator _generator;
protected final JsonSerializer _rootSerializer;
protected final TypeSerializer _typeSerializer;
protected final boolean _closeGenerator;
protected final boolean _cfgFlush;
protected final boolean _cfgCloseCloseable;
/*
/**********************************************************
/* State
/**********************************************************
*/
/**
* If {@link #_rootSerializer} is not defined (no root type
* was used for constructing {@link ObjectWriter}), we will
* use simple scheme for keeping track of serializers needed.
* Assumption is that
*/
protected PropertySerializerMap _dynamicSerializers;
/**
* State flag for keeping track of need to write matching END_ARRAY,
* if a START_ARRAY was written during initialization
*/
protected boolean _openArray;
protected boolean _closed;
/*
/**********************************************************
/* Life-cycle
/**********************************************************
*/
public SequenceWriter(DefaultSerializerProvider prov, JsonGenerator gen,
boolean closeGenerator, ObjectWriter.Prefetch prefetch)
throws IOException
{
_provider = prov;
_generator = gen;
_closeGenerator = closeGenerator;
_rootSerializer = prefetch.getValueSerializer();
_typeSerializer = prefetch.getTypeSerializer();
_config = prov.getConfig();
_cfgFlush = _config.isEnabled(SerializationFeature.FLUSH_AFTER_WRITE_VALUE);
_cfgCloseCloseable = _config.isEnabled(SerializationFeature.CLOSE_CLOSEABLE);
// important: need to cache "root value" serializers, to handle polymorphic
// types properly
_dynamicSerializers = PropertySerializerMap.emptyForRootValues();
}
/**
* Internal method called by {@link ObjectWriter}: should not be called by code
* outside {@code jackson-databind} classes.
*/
public SequenceWriter init(boolean wrapInArray) throws IOException
{
if (wrapInArray) {
_generator.writeStartArray();
_openArray = true;
}
return this;
}
/*
/**********************************************************
/* Public API, basic accessors
/**********************************************************
*/
/**
* Method that will return version information stored in and read from jar
* that contains this class.
*/
@Override
public Version version() {
return com.fasterxml.jackson.databind.cfg.PackageVersion.VERSION;
}
/*
/**********************************************************
/* Public API, write operations, related
/**********************************************************
*/
/**
* Method for writing given value into output, as part of sequence
* to write. If root type was specified for {@link ObjectWriter},
* value must be of compatible type (same or subtype).
*/
public SequenceWriter write(Object value) throws IOException
{
if (value == null) {
_provider.serializeValue(_generator, null);
return this;
}
if (_cfgCloseCloseable && (value instanceof Closeable)) {
return _writeCloseableValue(value);
}
JsonSerializer ser = _rootSerializer;
if (ser == null) {
Class type = value.getClass();
ser = _dynamicSerializers.serializerFor(type);
if (ser == null) {
ser = _findAndAddDynamic(type);
}
}
_provider.serializeValue(_generator, value, null, ser);
if (_cfgFlush) {
_generator.flush();
}
return this;
}
/**
* Method for writing given value into output, as part of sequence
* to write; further, full type (often generic, like {@link java.util.Map}
* is passed in case a new
* {@link JsonSerializer} needs to be fetched to handle type
*
* If root type was specified for {@link ObjectWriter},
* value must be of compatible type (same or subtype).
*/
public SequenceWriter write(Object value, JavaType type) throws IOException
{
if (value == null) {
_provider.serializeValue(_generator, null);
return this;
}
if (_cfgCloseCloseable && (value instanceof Closeable)) {
return _writeCloseableValue(value, type);
}
/* 15-Dec-2014, tatu: I wonder if this could become problematic. It shouldn't
* really, since trying to use differently paramterized types in a sequence
* is likely to run into other issues. But who knows; if it does become an
* issue, may need to implement alternative, JavaType-based map.
*/
JsonSerializer ser = _dynamicSerializers.serializerFor(type.getRawClass());
if (ser == null) {
ser = _findAndAddDynamic(type);
}
_provider.serializeValue(_generator, value, type, ser);
if (_cfgFlush) {
_generator.flush();
}
return this;
}
public SequenceWriter writeAll(Object[] value) throws IOException
{
for (int i = 0, len = value.length; i < len; ++i) {
write(value[i]);
}
return this;
}
// NOTE: redundant wrt variant that takes Iterable, but cannot remove or even
// deprecate due to backwards-compatibility needs
public > SequenceWriter writeAll(C container) throws IOException {
for (Object value : container) {
write(value);
}
return this;
}
/**
* @since 2.7
*/
public SequenceWriter writeAll(Iterable iterable) throws IOException
{
for (Object value : iterable) {
write(value);
}
return this;
}
@Override
public void flush() throws IOException {
if (!_closed) {
_generator.flush();
}
}
@Override
public void close() throws IOException
{
if (!_closed) {
_closed = true;
if (_openArray) {
_openArray = false;
_generator.writeEndArray();
}
if (_closeGenerator) {
_generator.close();
}
}
}
/*
/**********************************************************
/* Internal helper methods, serializer lookups
/**********************************************************
*/
protected SequenceWriter _writeCloseableValue(Object value) throws IOException
{
Closeable toClose = (Closeable) value;
try {
JsonSerializer ser = _rootSerializer;
if (ser == null) {
Class type = value.getClass();
ser = _dynamicSerializers.serializerFor(type);
if (ser == null) {
ser = _findAndAddDynamic(type);
}
}
_provider.serializeValue(_generator, value, null, ser);
if (_cfgFlush) {
_generator.flush();
}
Closeable tmpToClose = toClose;
toClose = null;
tmpToClose.close();
} finally {
if (toClose != null) {
try {
toClose.close();
} catch (IOException ioe) { }
}
}
return this;
}
protected SequenceWriter _writeCloseableValue(Object value, JavaType type) throws IOException
{
Closeable toClose = (Closeable) value;
try {
// 15-Dec-2014, tatu: As per above, could be problem that we do not pass generic type
JsonSerializer ser = _dynamicSerializers.serializerFor(type.getRawClass());
if (ser == null) {
ser = _findAndAddDynamic(type);
}
_provider.serializeValue(_generator, value, type, ser);
if (_cfgFlush) {
_generator.flush();
}
Closeable tmpToClose = toClose;
toClose = null;
tmpToClose.close();
} finally {
if (toClose != null) {
try {
toClose.close();
} catch (IOException ioe) { }
}
}
return this;
}
private final JsonSerializer _findAndAddDynamic(Class type) throws JsonMappingException
{
PropertySerializerMap.SerializerAndMapResult result;
if (_typeSerializer == null) {
result = _dynamicSerializers.findAndAddRootValueSerializer(type, _provider);
} else {
result = _dynamicSerializers.addSerializer(type,
new TypeWrappedSerializer(_typeSerializer, _provider.findValueSerializer(type, null)));
}
_dynamicSerializers = result.map;
return result.serializer;
}
private final JsonSerializer _findAndAddDynamic(JavaType type) throws JsonMappingException
{
PropertySerializerMap.SerializerAndMapResult result;
if (_typeSerializer == null) {
result = _dynamicSerializers.findAndAddRootValueSerializer(type, _provider);
} else {
result = _dynamicSerializers.addSerializer(type,
new TypeWrappedSerializer(_typeSerializer, _provider.findValueSerializer(type, null)));
}
_dynamicSerializers = result.map;
return result.serializer;
}
}
