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/JsonMappingException.java

package com.fasterxml.jackson.databind;

import java.io.Closeable;
import java.io.IOException;
import java.io.Serializable;
import java.util.*;

import com.fasterxml.jackson.annotation.JsonIgnore;

import com.fasterxml.jackson.core.*;

import com.fasterxml.jackson.databind.util.ClassUtil;

/**
 * Checked exception used to signal fatal problems with mapping of
 * content, distinct from low-level I/O problems (signaled using
 * simple {@link java.io.IOException}s) or data encoding/decoding
 * problems (signaled with {@link com.fasterxml.jackson.core.exc.StreamReadException},
 * {@link com.fasterxml.jackson.core.exc.StreamWriteException}).
 *<p>
 * One additional feature is the ability to denote relevant path
 * of references (during serialization/deserialization) to help in
 * troubleshooting.
 */
public class JsonMappingException
    extends DatabindException // @since 2.13
{
    private static final long serialVersionUID = 3L;

    /**
     * Let's limit length of reference chain, to limit damage in cases
     * of infinite recursion.
     */
    final static int MAX_REFS_TO_LIST = 1000;

    /*
    /**********************************************************************
    /* Helper classes
    /**********************************************************************
     */

    /**
     * Simple bean class used to contain references. References
     * can be added to indicate execution/reference path that
     * lead to the problem that caused this exception to be
     * thrown.
     */
    public static class Reference implements Serializable
    {
        private static final long serialVersionUID = 2L; // changes between 2.7 and 2.8

        // transient since 2.8
        protected transient Object _from;

        /**
         * Name of field (for beans) or key (for Maps) that is part
         * of the reference. May be null for Collection types (which
         * generally have {@link #_index} defined), or when resolving
         * Map classes without (yet) having an instance to operate on.
         */
        protected String _fieldName;

        /**
         * Index within a {@link Collection} instance that contained
         * the reference; used if index is relevant and available.
         * If either not applicable, or not available, -1 is used to
         * denote "not known" (or not relevant).
         */
        protected int _index = -1;

        /**
         * Lazily-constructed description of this instance; needed mostly to
         * allow JDK serialization to work in case where {@link #_from} is
         * non-serializable (and has to be dropped) but we still want to pass
         * actual description along.
         *
         * @since 2.8
         */
        protected String _desc;

        /**
         * Default constructor for deserialization/sub-classing purposes
         */
        protected Reference() { }

        public Reference(Object from) { _from = from; }

        public Reference(Object from, String fieldName) {
            _from = from;
            if (fieldName == null) {
                throw new NullPointerException("Cannot pass null fieldName");
            }
            _fieldName = fieldName;
        }

        public Reference(Object from, int index) {
            _from = from;
            _index = index;
        }

        // Setters to let Jackson deserialize instances, but not to be called from outside
        void setFieldName(String n) { _fieldName = n; }
        void setIndex(int ix) { _index = ix; }
        void setDescription(String d) { _desc = d; }

        /**
         * Object through which reference was resolved. Can be either
         * actual instance (usually the case for serialization), or
         * Class (usually the case for deserialization).
         *<p>
         * Note that this value must be `transient` to allow serializability (as
         * often such Object is NOT serializable; or, in case of `Class`, may
         * not available at the point of deserialization). As such will return
         * `null` if instance has been passed using JDK serialization.
         */
        @JsonIgnore
        public Object getFrom() { return _from; }

        public String getFieldName() { return _fieldName; }
        public int getIndex() { return _index; }
        public String getDescription() {
            if (_desc == null) {
                StringBuilder sb = new StringBuilder();

                if (_from == null) { // can this ever occur?
                    sb.append("UNKNOWN");
                } else {
                    Class<?> cls = (_from instanceof Class<?>) ? (Class<?>)_from : _from.getClass();
                    // Hmmh. Although Class.getName() is mostly ok, it does look
                    // butt-ugly for arrays.
                    // 06-Oct-2016, tatu: as per [databind#1403], `getSimpleName()` not so good
                    //   as it drops enclosing class. So let's try bit different approach
                    int arrays = 0;
                    while (cls.isArray()) {
                        cls = cls.getComponentType();
                        ++arrays;
                    }
                    sb.append(cls.getName());
                    while (--arrays >= 0) {
                        sb.append("[]");
                    }
                }
                sb.append('[');
                if (_fieldName != null) {
                    sb.append('"');
                    sb.append(_fieldName);
                    sb.append('"');
                } else if (_index >= 0) {
                    sb.append(_index);
                } else {
                    sb.append('?');
                }
                sb.append(']');
                _desc = sb.toString();
            }
            return _desc;
        }

        @Override
        public String toString() {
            return getDescription();
        }

        /**
         * May need some cleaning here, given that `from` may or may not be serializable.
         *
         * since 2.8
         */
        Object writeReplace() {
            // as per [databind#1195], need to ensure description is not null, since
            // `_from` is transient
            getDescription();
            return this;
        }
    }

    /*
    /**********************************************************************
    /* State/configuration
    /**********************************************************************
     */

    /**
     * Path through which problem that triggering throwing of
     * this exception was reached.
     */
    protected LinkedList<Reference> _path;

    /**
     * Underlying processor ({@link JsonParser} or {@link JsonGenerator}),
     * if known.
     *<p>
     * NOTE: typically not serializable hence <code>transient</code>
     *
     * @since 2.7
     */
    protected transient Closeable _processor;

    /*
    /**********************************************************************
    /* Life-cycle
    /**********************************************************************
     */

    /**
     * @deprecated Since 2.7 Use variant that takes {@link JsonParser} instead
     */
    @Deprecated // since 2.7
    public JsonMappingException(String msg) { super(msg); }

    /**
     * @deprecated Since 2.7 Use variant that takes {@link JsonParser} instead
     */
    @Deprecated // since 2.7
    public JsonMappingException(String msg, Throwable rootCause) { super(msg, rootCause); }

    /**
     * @deprecated Since 2.7 Use variant that takes {@link JsonParser} instead
     */
    @Deprecated // since 2.7
    public JsonMappingException(String msg, JsonLocation loc) { super(msg, loc); }

    /**
     * @deprecated Since 2.7 Use variant that takes {@link JsonParser} instead
     */
    @Deprecated // since 2.7
    public JsonMappingException(String msg, JsonLocation loc, Throwable rootCause) { super(msg, loc, rootCause); }

    /**
     * @since 2.7
     */
    public JsonMappingException(Closeable processor, String msg) {
        super(msg);
        _processor = processor;
        if (processor instanceof JsonParser) {
            // 17-Aug-2015, tatu: Use of token location makes some sense from databinding,
            //   since actual parsing (current) location is typically only needed for low-level
            //   parsing exceptions.
            _location = ((JsonParser) processor).getTokenLocation();
        }
    }

    /**
     * @since 2.7
     */
    public JsonMappingException(Closeable processor, String msg, Throwable problem) {
        super(msg, problem);
        _processor = processor;
        // 31-Jan-2020: [databind#2482] Retain original location
        if (problem instanceof JacksonException) {
            _location = ((JacksonException) problem).getLocation();
        } else if (processor instanceof JsonParser) {
            _location = ((JsonParser) processor).getTokenLocation();
        }
    }

    /**
     * @since 2.7
     */
    public JsonMappingException(Closeable processor, String msg, JsonLocation loc) {
        super(msg, loc);
        _processor = processor;
    }

    /**
     * @since 2.7
     */
    public static JsonMappingException from(JsonParser p, String msg) {
        return new JsonMappingException(p, msg);
    }

    /**
     * @since 2.7
     */
    public static JsonMappingException from(JsonParser p, String msg, Throwable problem) {
        return new JsonMappingException(p, msg, problem);
    }

    /**
     * @since 2.7
     */
    public static JsonMappingException from(JsonGenerator g, String msg) {
        return new JsonMappingException(g, msg, (Throwable) null);
    }

    /**
     * @since 2.7
     */
    public static JsonMappingException from(JsonGenerator g, String msg, Throwable problem) {
        return new JsonMappingException(g, msg, problem);
    }

    /**
     * @since 2.7
     */
    public static JsonMappingException from(DeserializationContext ctxt, String msg) {
        return new JsonMappingException(_parser(ctxt), msg);
    }

    /**
     * @since 2.7
     */
    public static JsonMappingException from(DeserializationContext ctxt, String msg, Throwable t) {
        return new JsonMappingException(_parser(ctxt), msg, t);
    }

    // @since 2.14
    private static JsonParser _parser(DeserializationContext ctxt) {
        return (ctxt == null) ? null : ctxt.getParser();
    }

    /**
     * @since 2.7
     */
    public static JsonMappingException from(SerializerProvider ctxt, String msg) {
        return new JsonMappingException(_generator(ctxt), msg);
    }

    /**
     * @since 2.7
     */
    public static JsonMappingException from(SerializerProvider ctxt, String msg, Throwable problem) {
        /* 17-Aug-2015, tatu: As per [databind#903] this is bit problematic as
         *   SerializerProvider instance does not currently hold on to generator...
         */
        return new JsonMappingException(_generator(ctxt), msg, problem);
    }

    // @since 2.14
    private static JsonGenerator _generator(SerializerProvider ctxt) {
        return (ctxt == null) ? null : ctxt.getGenerator();
    }
    
    /**
     * Factory method used when "upgrading" an {@link IOException} into
     * {@link JsonMappingException}: usually only needed to comply with
     * a signature.
     *<p>
     * NOTE: since 2.9 should usually NOT be used on input-side (deserialization)
     *    exceptions; instead use method(s) of <code>InputMismatchException</code>
     *
     * @since 2.1
     */
    public static JsonMappingException fromUnexpectedIOE(IOException src) {
        return new JsonMappingException(null,
                String.format("Unexpected IOException (of type %s): %s",
                        src.getClass().getName(),
                        ClassUtil.exceptionMessage(src)));
    }

    /**
     * Method that can be called to either create a new JsonMappingException
     * (if underlying exception is not a JsonMappingException), or augment
     * given exception with given path/reference information.
     *
     * This version of method is called when the reference is through a
     * non-indexed object, such as a Map or POJO/bean.
     */
    public static JsonMappingException wrapWithPath(Throwable src, Object refFrom,
            String refFieldName) {
        return wrapWithPath(src, new Reference(refFrom, refFieldName));
    }

    /**
     * Method that can be called to either create a new JsonMappingException
     * (if underlying exception is not a JsonMappingException), or augment
     * given exception with given path/reference information.
     *
     * This version of method is called when the reference is through an
     * index, which happens with arrays and Collections.
     */
    public static JsonMappingException wrapWithPath(Throwable src, Object refFrom, int index) {
        return wrapWithPath(src, new Reference(refFrom, index));
    }

    /**
     * Method that can be called to either create a new JsonMappingException
     * (if underlying exception is not a JsonMappingException), or augment
     * given exception with given path/reference information.
     */
    @SuppressWarnings("resource")
    public static JsonMappingException wrapWithPath(Throwable src, Reference ref)
    {
        JsonMappingException jme;
        if (src instanceof JsonMappingException) {
            jme = (JsonMappingException) src;
        } else {
            // [databind#2128]: try to avoid duplication
            String msg = ClassUtil.exceptionMessage(src);
            // Let's use a more meaningful placeholder if all we have is null
            if (msg == null || msg.isEmpty()) {
                msg = "(was "+src.getClass().getName()+")";
            }
            // 17-Aug-2015, tatu: Let's also pass the processor (parser/generator) along
            Closeable proc = null;
            if (src instanceof JacksonException) {
                Object proc0 = ((JacksonException) src).getProcessor();
                if (proc0 instanceof Closeable) {
                    proc = (Closeable) proc0;
                }
            }
            jme = new JsonMappingException(proc, msg, src);
        }
        jme.prependPath(ref);
        return jme;
    }

    /**
     * @since 2.13
     */
    public JsonMappingException withCause(Throwable cause) {
        initCause(cause);
        return this;
    }

    /*
    /**********************************************************************
    /* Accessors/mutators
    /**********************************************************************
     */

    /**
     * Method for accessing full structural path within type hierarchy
     * down to problematic property.
     */
    public List<Reference> getPath()
    {
        if (_path == null) {
            return Collections.emptyList();
        }
        return Collections.unmodifiableList(_path);
    }

    /**
     * Method for accessing description of path that lead to the
     * problem that triggered this exception
     */
    public String getPathReference()
    {
        return getPathReference(new StringBuilder()).toString();
    }

    public StringBuilder getPathReference(StringBuilder sb)
    {
        _appendPathDesc(sb);
        return sb;
    }
    
    /**
     * Method called to prepend a reference information in front of
     * current path
     */
    @Override
    public void prependPath(Object referrer, String fieldName) {
        prependPath(new Reference(referrer, fieldName));
    }

    /**
     * Method called to prepend a reference information in front of
     * current path
     */
    @Override
    public void prependPath(Object referrer, int index) {
        prependPath(new Reference(referrer, index));
    }

    public void prependPath(Reference r)
    {
        if (_path == null) {
            _path = new LinkedList<Reference>();
        }
        /* Also: let's not increase without bounds. Could choose either
         * head or tail; tail is easier (no need to ever remove), as
         * well as potentially more useful so let's use it:
         */
        if (_path.size() < MAX_REFS_TO_LIST) {
            _path.addFirst(r);
        }
    }

    /*
    /**********************************************************************
    /* Overridden methods
    /**********************************************************************
     */

    @Override // since 2.8
    @JsonIgnore // as per [databind#1368]
    public Object getProcessor() { return _processor; }

    @Override
    public String getLocalizedMessage() {
        return _buildMessage();
    }
    
    /**
     * Method is overridden so that we can properly inject description
     * of problem path, if such is defined.
     */
    @Override
    public String getMessage() {
        return _buildMessage();
    }

    protected String _buildMessage()
    {
        // First: if we have no path info, let's just use parent's definition as is
        String msg = super.getMessage();
        if (_path == null) {
            return msg;
        }
        StringBuilder sb = (msg == null) ? new StringBuilder() : new StringBuilder(msg);
        /* 18-Feb-2009, tatu: initially there was a linefeed between
         *    message and path reference; but unfortunately many systems
         *   (loggers, junit) seem to assume linefeeds are only added to
         *   separate stack trace.
         */
        sb.append(" (through reference chain: ");
        sb = getPathReference(sb);
        sb.append(')');
        return sb.toString();
    }

    @Override
    public String toString()
    {
        return getClass().getName()+": "+getMessage();
    }

    /*
    /**********************************************************************
    /* Internal methods
    /**********************************************************************
     */

    protected void _appendPathDesc(StringBuilder sb)
    {
        if (_path == null) {
            return;
        }
        Iterator<Reference> it = _path.iterator();
        while (it.hasNext()) {
            sb.append(it.next().toString());
            if (it.hasNext()) {
                sb.append("->");
            }
        }
    }
}

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

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