Jackson is "the Java JSON library" or "the best JSON parser for Java". Or simply as "JSON for Java".

Jackson Databind Source Code files are provided in the source packge (jackson-databind-2.14.0-sources.jar). You can download it at Jackson Maven Website.

You can also browse Jackson Databind Source Code below:

⏎ com/fasterxml/jackson/databind/SequenceWriter.java

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).
 *<p>
 * Differences from {@link ObjectWriter} include:
 *<ul>
 *  <li>Instances of {@link SequenceWriter} are stateful, and not thread-safe:
 *    if sharing, external synchronization must be used.
 *  <li>Explicit {@link #close} is needed after all values have been written
 *     ({@link ObjectWriter} can auto-close after individual value writes)
 *</ul>
 * 
 * @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<Object> _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<Object> 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<Object> 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 <C extends Collection<?>> 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<Object> 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<Object> 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<Object> _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<Object> _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;
    }
}

⏎ com/fasterxml/jackson/databind/SequenceWriter.java

Or download all of them as a single archive file:

File name: jackson-databind-2.14.0-sources.jar
File size: 1187952 bytes
Release date: 2022-11-05
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