Icar fast JSON push parser (SAX-like)

Designed in a minimalistic way (as little code as possible), with no external dependency, and released under Creative Commons Zero (CC0) "public domain" license.

Can "stream" JSON on the fly: as a push parser, can process a continuous JSON flow as it comes (drawback: can't be used to validate JSON, as it doesn't expect it to be complete).

Fast enough to parse a 50 Mo JSON file in about 3 seconds !

Maven dependency to include in your pom

<dependency>
  <groupId>com.gibello</groupId>
  <artifactId>icar-json</artifactId>
  <version>1.0.1</version>
</dependency>

Build with maven

$ mvn clean install

Quick start: pretty-print JSON

$ java -jar target/icar-json-1.0.2-SNAPSHOT.jar any-json-file.json

How to develop your own parser

Icar is a push, event-based parser.

Writing your own parser requires to override the com.gibello.icar.json.parser.DefaultHandler class (or implement the com.gibello.icar.json.parser.eventHandler interface).

For example:

package my.parser;

import com.gibello.icar.json.parser.DefaultHandler;
import com.gibello.icar.json.parser.JsonParser;

import java.io.ByteArrayInputStream;

/**
 * Provide a handler
 */
public class MyHandler extends DefaultHandler {

  @Override
  public void key(String key) throws Exception {
    System.out.println("Got key: " + key);
  }

  @Override
  public void simpleValue(String val) throws Exception {
    System.out.println("Got value: " + val);
  }

  /**
   * Main program: parse a JSON String!
   */
  public static void main(String args[]) throws Exception {
    JsonParser parser = new JsonParser();
    String json = "{ \"productInfo\": \"Icar JSON Parser\" }";
    parser.parse(new ByteArrayInputStream(json.getBytes()), new MyHandler());
  }

}

Tip for faster parsing of JSON files

Using a BufferedInputStream is almost 10 times faster than a simple FileInputStream.

Example:

parser.parse(new BufferedInputStream(new FileInputStream(jsonFile)), handler);
// Code above is 10 times faster than: parser.parse(new FileInputStream(jsonFile), handler);

Embed the code in your project ?

Why not, as an alternative to a dependency ?

One can just pick the com.gibello.icar.json.parser package (in src/main/java/com/gibello/icar/json/parser). It is just 3 files, less than 300 lines of code, and is enough.

Feel free to rename, move to your own package, the CC0 license allows anything you like :)