kenta-shimizu / json4java8

This library is JSON (RFC8259) parser implementation on Java8. Also supports JSONC reading.

json4java8

Introduction

This library is JSON (RFC8259) parser implementation on Java8. Also supports JSONPath, JSONC reading.

Example of use

public class POJO {
	
	public int num;
	public String str;
	public boolean bool;
	public List<String> array;
	
	public POJO() {
		num = 100;
		str = "STRING";
		bool = true;
		array = Arrays.asList("a", "b", "c");
	}
	
	public static void main(String[] args) {

		POJO pojo = new POJO();
		String json = JsonHub.fromPojo(pojo).toJson();
		System.out.println(json);

		/* {"num":100,"str":"STRING","bool":true,"array":["a","b","c"]} */
	}
}

Javadoc

Convert

1. Create JsonHub instance from #fromPojo, #fromJson, #fromFile, #fromBytes.
2. Convert using #toPojo, #toJson, #writeFile, #getBytes, #writeBytes.

From POJO (Plain Old Java Objec) to JSON

/* to String */
String json = JsonHub.fromPojo(pojo).toJson();

/* to Writer */
Writer writer = new StringWriter()
JsonHub.fromPojo(pojo).toJson(writer);

/* to file */
Path path = Paths.get("path/of/file.json");
JsonHub.fromPojo(pojo).writeFile(path);

From POJO conditions

• Field is public
• Field is not static

See also "/src/examples/example02/PojoParseToJsonString.java"
See also "/src/examples/example03/PojoWriteJsonToFile.java"

From JSON to POJO

/* from JSON String */
String json = "{\"num\": 100, \"str\": \"STRING\", \"bool\": true}";
Pojo pojo = JsonHub.fromJson(json).toPojo(Pojo.class);

/* from Reader */
Reader reader = new StringReader(json);
Pojo pojo = JsonHub.fromJson(reader).toPojo(Pojo.class);

/* from file */
Path path = Paths.get("path/of/file.json");
Pojo pojo = JsonHub.fromFile(path).toPojo(Pojo.class);

To POJO conditions

• Class has public new() (arguments is 0)
• Field is public
• Field is not static
• Field is not final

See also "/src/examples/example01/JsonStringParseToPojo.java"
See also "/src/examples/example04/ReadJsonFileParseToPojo.java"

From POJO to UTF-8 bytes

/* to bytes */
byte[] bytes = JsonHub.fromPojo(pojo).getBytes();

/* to OutputStream */
OutputStream strm = new ByteArrayOutputStream();
JsonHub.fromPojo(pojo).writeBytes(strm);

From UTF-8 bytes to POJO

/* from bytes */
byte[] bytes = json.getBytes(StandardCharsets.UTF_8);
Pojo pojo = JsonHub.fromBytes(bytes).toPojo(Pojo.class);

/* from InputStream */
InputStream strm = new ByteArrayInputStream(bytes);
Pojo pojo = JsonHub.fromBytes(strm).toPojo(Pojo.class);

Pretty Print

1. Create JsonHub instance from #fromPojo, ...
2. PrettyPrint using #prettyPrint

/* to String */
String prettyPrintJson = JsonHub.fromPojo(pojo).prettyPrint();

/* write to file */
Path path = Paths.get("path/of/file.json");
JsonHub.fromPojo(pojo).prettyPrint(path);

/* write to Writer */
Writer writer = new StringWriter();
JsonHub.fromPojo(pojo).prettyPrint(writer);

See also "/src/examples/example05/PojoParseToPrettyPrintJsonString.java"
See also "/src/examples/example06/PojoWritePrettyPrintJsonToFile.java"
See also "/src/examples/example09/ChangePrettyPrintFormat.java"

Get value from JsonHub instance

String json
= "{                                 "
+ "  \"num\":   100,                 "
+ "  \"str\":   \"STRING\",          "
+ "  \"bool\":  true,                "
+ "  \"array\": [\"a\", \"b\", \"c\"]"
+ "}                                 ";

JsonHub jh = JsonHub.fromJson(json);

int num = jh.get("num").intValue();  /* 100 */
String str = jh.get("str").toString();  /* "STRING" */
boolean bool = jh.get("bool").booleanValue();  /* true */
String array_0 = jh.get("array").get(0).toString();  /* "a" */

See also "/src/examples/example08/ForEachJsonHub.java"

Methods for seek value in OBJECT or ARRAY

✓ is available.
"blank" is throw JsonHubUnsupportedOperationException.

Method	Object	Array	Number	String	true	false	null
get(CharSequence)	✓
get(String...)	✓
get(int)		✓
iterator()	✓	✓
stream()	✓	✓
forEach(Consumer<? super JsonHub)	✓	✓
forEach(BiConsumer<? super JsonString, ? super JsonHub)	✓	✓
values()	✓	✓
keySet()	✓
containsKey(CharSequence)	✓
getOrDefault(CharSequence)	✓
getOrDefault(CharSequence, JsonHub)	✓

Methods for get value

✓ is available.
"blank" is throw JsonHubUnsupportedOperationException.

Method	Object	Array	Number	String	true	false	null
intValue()			✓
longValue()			✓
doubleValue()			✓
booleanValue()					✓	✓
optionalInt()	✓	✓	✓	✓	✓	✓	✓
optionalLong()	✓	✓	✓	✓	✓	✓	✓
optionalDouble()	✓	✓	✓	✓	✓	✓	✓
optionalBoolean()	✓	✓	✓	✓	✓	✓	✓
optionalNumber()	✓	✓	✓	✓	✓	✓	✓
optionalString()	✓	✓	✓	✓	✓	✓	✓
length()	✓	✓		✓
isEmpty()	✓	✓		✓
toString()	✓	✓	✓	✓	✓	✓	✓

Methods for check type

✓ is available.

Method	Object	Array	Number	String	true	false	null
type()	✓	✓	✓	✓	✓	✓	✓
isObject()	✓	✓	✓	✓	✓	✓	✓
isArray()	✓	✓	✓	✓	✓	✓	✓
isNumber()	✓	✓	✓	✓	✓	✓	✓
isString()	✓	✓	✓	✓	✓	✓	✓
isTrue()	✓	✓	✓	✓	✓	✓	✓
isFalse()	✓	✓	✓	✓	✓	✓	✓
isBoolean()	✓	✓	✓	✓	✓	✓	✓
isNull()	✓	✓	✓	✓	✓	✓	✓
nonNull()	✓	✓	✓	✓	✓	✓	✓

Create JsonHub instance by builder

Use JsonHubBuilder

JsonHubBuilder jhb = JsonHub.getBuilder();

JsonHub jh = jhb.object(
    jhb.pair("str", "STRING"),
    jhb.pair("num", 100),
    jhb.pair("bool", true),
    jhb.pair("array", jhb.array(
        jhb.build("a"),
        jhb.build("b"),
        jhb.build("c")
    ))
);

String json = jh.toJson();

System.out.println(json);

/* {"str":"STRING","num":100,"bool":true,"array":["a","b","c"]} */

See also "/src/examples/example07/CreateJsonStringByBuilder.java"

JSONPath

JSONPath is "https://goessner.net/articles/JsonPath/"

Supports

Operator	Description
$	The root element.
*	Wildcard, all object-name or array-number.
..	Recursive descent.
.<name>	Child object name operator.
[<name>(, <name>)]	Child object name(s) operator.
[<number>(, <number>)]	Child array number(s) operator.
[start:end:step]	Child array slice operator.

Not support @, ?(), ()

List<JsonHub> results = jh.jsonPath("$.store.book[*].author");

See also "/src/examples/example11/JsonPath.java"

JSONC reading

JSONC (JSON with comments) support.

• /* comment... */
• // comment...
• Array trailing comma(,)
• Object trailing comma(,)

Path path = Paths.get("path/of/file.jsonc");
JsonHub jh = JsoncReader.fromFile(path);
System.out.println(jh.prettyPrint());

See also "/src/examples/example10/ReadJsoncFile.java"