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"