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

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

You can also browse Jackson Core Source Code below:

⏎ com/fasterxml/jackson/core/io/SegmentedStringWriter.java

package com.fasterxml.jackson.core.io;

import java.io.*;

import com.fasterxml.jackson.core.util.BufferRecycler;
import com.fasterxml.jackson.core.util.TextBuffer;

/**
 * Efficient alternative to {@link StringWriter}, based on using segmented
 * internal buffer. Initial input buffer is also recyclable.
 *<p>
 * This class is most useful when serializing JSON content as a String:
 * if so, instance of this class can be given as the writer to
 * <code>JsonGenerator</code>.
 */
public final class SegmentedStringWriter extends Writer
{
    final private TextBuffer _buffer;

    public SegmentedStringWriter(BufferRecycler br) {
        super();
        _buffer = new TextBuffer(br);
    }

    /*
    /**********************************************************
    /* java.io.Writer implementation
    /**********************************************************
     */

    @Override
    public Writer append(char c) {
        write(c);
        return this;
    }

    @Override
    public Writer append(CharSequence csq) {
        String str = csq.toString();
        _buffer.append(str, 0, str.length());
        return this;
    }

    @Override
    public Writer append(CharSequence csq, int start, int end) {
        String str = csq.subSequence(start, end).toString();
        _buffer.append(str, 0, str.length());
        return this;
    }

    @Override public void close() { } // NOP
    @Override public void flush() { } // NOP

    @Override
    public void write(char[] cbuf) { _buffer.append(cbuf, 0, cbuf.length); }

    @Override
    public void write(char[] cbuf, int off, int len) { _buffer.append(cbuf, off, len); }

    @Override
    public void write(int c) { _buffer.append((char) c); }

    @Override
    public void write(String str) { _buffer.append(str, 0, str.length()); }

    @Override
    public void write(String str, int off, int len) { _buffer.append(str, off, len); }

    /*
    /**********************************************************
    /* Extended API
    /**********************************************************
     */

    /**
     * Main access method that will construct a String that contains
     * all the contents, release all internal buffers we may have,
     * and return result String.
     * Note that the method is not idempotent -- if called second time,
     * will just return an empty String.
     *
     * @return String that contains all aggregated content
     */
    public String getAndClear() {
        String result = _buffer.contentsAsString();
        _buffer.releaseBuffers();
        return result;
    }
}

⏎ com/fasterxml/jackson/core/io/SegmentedStringWriter.java

Or download all of them as a single archive file:

File name: jackson-core-2.14.0-sources.jar
File size: 497693 bytes
Release date: 2022-11-05
Download 

⇒ Download and Install Jackson Binary Package

⇐ What Is Jackson

⇑ Downloading and Reviewing jackson-*.jar

⇑⇑ Jackson - Java JSON library