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/deser/std/StringArrayDeserializer.java

package com.fasterxml.jackson.databind.deser.std;

import java.io.IOException;
import java.util.Objects;

import com.fasterxml.jackson.annotation.JsonFormat;

import com.fasterxml.jackson.core.*;

import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.annotation.JacksonStdImpl;
import com.fasterxml.jackson.databind.cfg.CoercionAction;
import com.fasterxml.jackson.databind.cfg.CoercionInputShape;
import com.fasterxml.jackson.databind.deser.ContextualDeserializer;
import com.fasterxml.jackson.databind.deser.NullValueProvider;
import com.fasterxml.jackson.databind.deser.impl.NullsConstantProvider;
import com.fasterxml.jackson.databind.jsontype.TypeDeserializer;
import com.fasterxml.jackson.databind.type.LogicalType;
import com.fasterxml.jackson.databind.util.AccessPattern;
import com.fasterxml.jackson.databind.util.ObjectBuffer;

/**
 * Separate implementation for serializing String arrays (instead of
 * using {@link ObjectArrayDeserializer}.
 * Used if (and only if) no custom value deserializers are used.
 */
@JacksonStdImpl
public final class StringArrayDeserializer
// 28-Oct-2016, tatu: Should do this:
//    extends ContainerDeserializerBase<String[]>
// but for now won't:
    extends StdDeserializer<String[]>
    implements ContextualDeserializer
{
    private static final long serialVersionUID = 2L;

    private final static String[] NO_STRINGS = new String[0];

    public final static StringArrayDeserializer instance = new StringArrayDeserializer();

    /**
     * Value serializer to use, if not the standard one (which is inlined)
     */
    protected JsonDeserializer<String> _elementDeserializer;

    /**
     * Handler we need for dealing with null values as elements
     *
     * @since 2.9
     */
    protected final NullValueProvider _nullProvider;

    /**
     * Specific override for this instance (from proper, or global per-type overrides)
     * to indicate whether single value may be taken to mean an unwrapped one-element array
     * or not. If null, left to global defaults.
     *
     * @since 2.7
     */
    protected final Boolean _unwrapSingle;

    /**
     * Marker flag set if the <code>_nullProvider</code> indicates that all null
     * content values should be skipped (instead of being possibly converted).
     *
     * @since 2.9
     */
    protected final boolean _skipNullValues;
    
    public StringArrayDeserializer() {
        this(null, null, null);
    }

    @SuppressWarnings("unchecked")
    protected StringArrayDeserializer(JsonDeserializer<?> deser,
            NullValueProvider nuller, Boolean unwrapSingle) {
        super(String[].class);
        _elementDeserializer = (JsonDeserializer<String>) deser;
        _nullProvider = nuller;
        _unwrapSingle = unwrapSingle;
        _skipNullValues = NullsConstantProvider.isSkipper(nuller);
    }

    @Override // since 2.12
    public LogicalType logicalType() {
        return LogicalType.Array;
    }

    @Override // since 2.9
    public Boolean supportsUpdate(DeserializationConfig config) {
        return Boolean.TRUE;
    }

    @Override // since 2.9
    public AccessPattern getEmptyAccessPattern() {
        // immutable, shareable so:
        return AccessPattern.CONSTANT;
    }

    @Override // since 2.9
    public Object getEmptyValue(DeserializationContext ctxt) throws JsonMappingException {
        return NO_STRINGS;
    }

    /**
     * Contextualization is needed to see whether we can "inline" deserialization
     * of String values, or if we have to use separate value deserializer.
     */
    @Override
    public JsonDeserializer<?> createContextual(DeserializationContext ctxt, BeanProperty property)
            throws JsonMappingException
    {
        JsonDeserializer<?> deser = _elementDeserializer;
        // May have a content converter
        deser = findConvertingContentDeserializer(ctxt, property, deser);
        JavaType type = ctxt.constructType(String.class);
        if (deser == null) {
            deser = ctxt.findContextualValueDeserializer(type, property);
        } else { // if directly assigned, probably not yet contextual, so:
            deser = ctxt.handleSecondaryContextualization(deser, property, type);
        }
        // One more thing: allow unwrapping?
        Boolean unwrapSingle = findFormatFeature(ctxt, property, String[].class,
                JsonFormat.Feature.ACCEPT_SINGLE_VALUE_AS_ARRAY);
        NullValueProvider nuller = findContentNullProvider(ctxt, property, deser);
        // Ok ok: if all we got is the default String deserializer, can just forget about it
        if ((deser != null) && isDefaultDeserializer(deser)) {
            deser = null;
        }
        if ((_elementDeserializer == deser)
                && (Objects.equals(_unwrapSingle, unwrapSingle))
                && (_nullProvider == nuller)) {
            return this;
        }
        return new StringArrayDeserializer(deser, nuller, unwrapSingle);
    }

    @Override
    public String[] deserialize(JsonParser p, DeserializationContext ctxt) throws IOException
    {
        // Ok: must point to START_ARRAY (or equivalent)
        if (!p.isExpectedStartArrayToken()) {
            return handleNonArray(p, ctxt);
        }
        if (_elementDeserializer != null) {
            return _deserializeCustom(p, ctxt, null);
        }

        final ObjectBuffer buffer = ctxt.leaseObjectBuffer();
        Object[] chunk = buffer.resetAndStart();

        int ix = 0;

        try {
            while (true) {
                String value = p.nextTextValue();
                if (value == null) {
                    JsonToken t = p.currentToken();
                    if (t == JsonToken.END_ARRAY) {
                        break;
                    }
                    if (t == JsonToken.VALUE_NULL) {
                        if (_skipNullValues) {
                            continue;
                        }
                        value = (String) _nullProvider.getNullValue(ctxt);
                    } else {
                        value = _parseString(p, ctxt, _nullProvider);
                    }
                }
                if (ix >= chunk.length) {
                    chunk = buffer.appendCompletedChunk(chunk);
                    ix = 0;
                }
                chunk[ix++] = value;
            }
        } catch (Exception e) {
            throw JsonMappingException.wrapWithPath(e, chunk, buffer.bufferedSize() + ix);
        }
        String[] result = buffer.completeAndClearBuffer(chunk, ix, String.class);
        ctxt.returnObjectBuffer(buffer);
        return result;
    }

    /**
     * Offlined version used when we do not use the default deserialization method.
     */
    protected final String[] _deserializeCustom(JsonParser p, DeserializationContext ctxt,
            String[] old) throws IOException
    {
        final ObjectBuffer buffer = ctxt.leaseObjectBuffer();
        int ix;
        Object[] chunk;

        if (old == null) {
            ix = 0;
            chunk = buffer.resetAndStart();
        } else {
            ix = old.length;
            chunk = buffer.resetAndStart(old, ix);
        }
        
        final JsonDeserializer<String> deser = _elementDeserializer;

        try {
            while (true) {
                /* 30-Dec-2014, tatu: This may look odd, but let's actually call method
                 *   that suggest we are expecting a String; this helps with some formats,
                 *   notably XML. Note, however, that while we can get String, we can't
                 *   assume that's what we use due to custom deserializer
                 */
                String value;
                if (p.nextTextValue() == null) {
                    JsonToken t = p.currentToken();
                    if (t == JsonToken.END_ARRAY) {
                        break;
                    }
                    // Ok: no need to convert Strings, but must recognize nulls
                    if (t == JsonToken.VALUE_NULL) {
                        if (_skipNullValues) {
                            continue;
                        }
                        value = (String) _nullProvider.getNullValue(ctxt);
                    } else {
                        value = deser.deserialize(p, ctxt);
                    }
                } else {
                    value = deser.deserialize(p, ctxt);
                }
                if (ix >= chunk.length) {
                    chunk = buffer.appendCompletedChunk(chunk);
                    ix = 0;
                }
                chunk[ix++] = value;
            }
        } catch (Exception e) {
            // note: pass String.class, not String[].class, as we need element type for error info
            throw JsonMappingException.wrapWithPath(e, String.class, ix);
        }
        String[] result = buffer.completeAndClearBuffer(chunk, ix, String.class);
        ctxt.returnObjectBuffer(buffer);
        return result;
    }

    @Override
    public Object deserializeWithType(JsonParser p, DeserializationContext ctxt, TypeDeserializer typeDeserializer) throws IOException {
        return typeDeserializer.deserializeTypedFromArray(p, ctxt);
    }

    @Override
    public String[] deserialize(JsonParser p, DeserializationContext ctxt,
            String[] intoValue) throws IOException
    {
        // Ok: must point to START_ARRAY (or equivalent)
        if (!p.isExpectedStartArrayToken()) {
            String[] arr = handleNonArray(p, ctxt);
            if (arr == null) {
                return intoValue;
            }
            final int offset = intoValue.length;
            String[] result = new String[offset + arr.length];
            System.arraycopy(intoValue, 0, result, 0, offset);
            System.arraycopy(arr, 0, result, offset, arr.length);
            return result;
        }

        if (_elementDeserializer != null) {
            return _deserializeCustom(p, ctxt, intoValue);
        }
        final ObjectBuffer buffer = ctxt.leaseObjectBuffer();
        int ix = intoValue.length;
        Object[] chunk = buffer.resetAndStart(intoValue, ix);

        try {
            while (true) {
                String value = p.nextTextValue();
                if (value == null) {
                    JsonToken t = p.currentToken();
                    if (t == JsonToken.END_ARRAY) {
                        break;
                    }
                    if (t == JsonToken.VALUE_NULL) {
                        // 03-Feb-2017, tatu: Should we skip null here or not?
                        if (_skipNullValues) {
                            return NO_STRINGS;
                        }
                        value = (String) _nullProvider.getNullValue(ctxt);
                    } else {
                        value = _parseString(p, ctxt, _nullProvider);
                    }
                }
                if (ix >= chunk.length) {
                    chunk = buffer.appendCompletedChunk(chunk);
                    ix = 0;
                }
                chunk[ix++] = value;
            }
        } catch (Exception e) {
            throw JsonMappingException.wrapWithPath(e, chunk, buffer.bufferedSize() + ix);
        }
        String[] result = buffer.completeAndClearBuffer(chunk, ix, String.class);
        ctxt.returnObjectBuffer(buffer);
        return result;
    }

    private final String[] handleNonArray(JsonParser p, DeserializationContext ctxt) throws IOException
    {
        // implicit arrays from single values?
        boolean canWrap = (_unwrapSingle == Boolean.TRUE) ||
                ((_unwrapSingle == null) &&
                        ctxt.isEnabled(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY));
        if (canWrap) {
            String value;
            if (p.hasToken(JsonToken.VALUE_NULL)) {
                value = (String) _nullProvider.getNullValue(ctxt);
            } else {
                if (p.hasToken(JsonToken.VALUE_STRING)) {
                    String textValue = p.getText();
                    // https://github.com/FasterXML/jackson-dataformat-xml/issues/513
                    if (textValue.isEmpty()) {
                        final CoercionAction act = ctxt.findCoercionAction(logicalType(), handledType(),
                                CoercionInputShape.EmptyString);
                        if (act != CoercionAction.Fail) {
                            return (String[]) _deserializeFromEmptyString(p, ctxt, act, handledType(),
                                    "empty String (\"\")");
                        }
                    } else if (_isBlank(textValue)) {
                        final CoercionAction act = ctxt.findCoercionFromBlankString(logicalType(), handledType(),
                                CoercionAction.Fail);
                        if (act != CoercionAction.Fail) {
                            return (String[]) _deserializeFromEmptyString(p, ctxt, act, handledType(),
                                    "blank String (all whitespace)");
                        }
                    }
                    // if coercion failed, we can still add it to an array
                }

                value = _parseString(p, ctxt, _nullProvider);
            }
            return new String[] { value };
        }
        if (p.hasToken(JsonToken.VALUE_STRING)) {
            return _deserializeFromString(p, ctxt);
        }
        return (String[]) ctxt.handleUnexpectedToken(_valueClass, p);
    }
}

⏎ com/fasterxml/jackson/databind/deser/std/StringArrayDeserializer.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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