This a Coding Dojo prepared for the HOUG (http://www.houg.hu/) Szakmai nap 2016

1. JSON ALAPOK

2. {
"name": "John Doe",
"age": 29,
"siblings": ["Jane Doe", "Herry Doe"],
"address": {
"city": "Budapest",
"street": "Deak Square"
},
"alive": false,
"description": null
}

3. {
"name": "John Doe", // <­ String
"age": 29, // <­ Number
"siblings": ["Jane Doe", "Herry Doe"], // <­ Array
"address": {
"city": "Budapest",
"street": "Deak Square"
}, // <­ Object
"alive": false, // <­ true/false
"description": null // <­ null
}

4. PROGRAMMING MODELS
object model
streaming model

5. PACKAGE: JAVAX.JSON
reader interface
writer interface
model builder interface

6. PACKAGE: JAVAX.JSON.STREAM
parser interface
generator interface

7. LET'S CODE

8. Docs:
https://docs.oracle.com/javaee/7/api/javax/json/package-
summary.html

9. EXERCISE 1:
Olvassunk be json modelt stringből Használjunk hozzá
StringReader-t és JsonReader-t
Fordításhoz használjuk a Glassfish implementációt:
org.glassfish; javax.json; 1.0.4
http://mvnrepository.com/artifact/org.glassfish/javax.json/1.0.4

10. <!­­?xml version="1.0" encoding="UTF­8"?­­>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.
<modelversion>4.0.0</modelversion>
<groupid>hu.huog.jsonp</groupid>
<artifactid>exercises</artifactid>
<version>1.0­SNAPSHOT</version>
<packaging>jar</packaging>
<build>
<plugins>
<plugin>
<groupid>org.apache.maven.plugins</groupid>
<artifactid>maven­jar­plugin</artifactid>
<configuration>
<archive>
<manifest>
<mainclass>Exercise00</mainclass>
<addclasspath>true</addclasspath>
</manifest>
</archive>

11. </configuration>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupid>org.glassfish</groupid>
<artifactid>javax.json</artifactid>
<version>1.0.4</version>
</dependency>
</dependencies>
</project>

12. import javax.json.Json;
import javax.json.JsonReader;
import javax.json.JsonStructure;
import java.io.StringReader;
public class Exercise01 {
private static final String jsonString = "{ "name": "John Snow"}"
public static void main(String[] args) {
JsonReader reader = Json.createReader(new StringReader(jsonString));
JsonStructure jsonst = reader.read();
reader.close();
System.out.println("json: " + jsonst);
}
}

13. EXERCISE 2:
Készítsünk json modelt builder segítségével és írjuk ki
stringbe Használjunk JsonObjectBuilder-t,
JsonArrayBuilder-t, JsonWriter-t, StringWriter-t

14. import javax.json.Json;
import javax.json.JsonObject;
import javax.json.JsonWriter;
import java.io.StringWriter;
public class Exercise01 {
public static void main(String[] args) {
JsonObject model = Json.createObjectBuilder()
.add("firstName", "Duke")
.add("lastName", "Java")
.add("age", 18)
.add("streetAddress", "100 Internet Dr")
.add("city", "JavaTown")
.add("state", "JA")
.add("postalCode", "12345")
.add("phoneNumbers", Json.createArrayBuilder()
.add(Json.createObjectBuilder()
.add("type", "mobile")
.add("number", "111­111­1111"))
.add(Json.createObjectBuilder()

15. .add("type", "home")
.add("number", "222­222­2222")))
.build();
StringWriter strWriter = new StringWriter();
JsonWriter jsonWriter = Json.createWriter(strWriter);
jsonWriter.writeObject(model);
jsonWriter.close();
String jsonStr = strWriter.toString();
System.out.println("json: " + jsonStr);
}
}

16. EXERCISE 3:
Parsoljunk json stringet és irassuk ki a parse eventeket
Használjunk JsonParser-t

17. import javax.json.Json;
import javax.json.stream.JsonParser;
import java.io.StringReader;
public class Exercise03 {
private static final String jsonString = "{ "name": "John Snow"}"
public static void main(String[] args) {
JsonParser parser = Json.createParser(new StringReader(jsonString));
while (parser.hasNext()) {
JsonParser.Event event = parser.next();
switch(event) {
case START_ARRAY:
case END_ARRAY:
case START_OBJECT:
case END_OBJECT:
case VALUE_FALSE:
case VALUE_NULL:
case VALUE_TRUE:

18. System.out.println(event.toString());
break;
case KEY_NAME:
System.out.print(event.toString() + " " +
parser.getString() + " ­ ");
break;
case VALUE_STRING:
case VALUE_NUMBER:
System.out.println(event.toString() + " " +
parser.getString());
break;
}
}
}
}

19. EXERCISE 4:
Készítsünk JSON stringet geerátor segítségével Használjunk
JsonGenerator-t, StringWriter-t

20. import javax.json.Json;
import javax.json.stream.JsonGenerator;
import java.io.StringWriter;
public class Exercise04 {
public static void main(String[] args) {
StringWriter writer = new StringWriter();
JsonGenerator gen = Json.createGenerator(writer);
gen.writeStartObject()
.write("firstName", "Duke")
.write("lastName", "Java")
.write("age", 18)
.write("streetAddress", "100 Internet Dr")
.write("city", "JavaTown")
.write("state", "JA")
.write("postalCode", "12345")
.writeStartArray("phoneNumbers")
.writeStartObject()
.write("type", "mobile")
.write("number", "111­111­1111")

21. .writeEnd()
.writeStartObject()
.write("type", "home")
.write("number", "222­222­2222")
.writeEnd()
.writeEnd()
.writeEnd();
gen.close();
String jsonString = writer.toString();
System.out.println("json:" + jsonString);
}
}

22. JSR374 (JSON PROCESSING 1.1)
wget http://download.oracle.com/otn-pub/jcp/json_p-
1_1-edr-spec/jsonp-1.1-edr1-sources.zip
wget http://download.oracle.com/otn-pub/jcp/json_p-
1_1-edr-spec/jsonp-1.1-edr1-javadoc.zip
http://download.oracle.com/otndocs/jcp/json_p-1_1-edr-
spec/index.html

23. RESOURCES:
https://docs.oracle.com/javaee/7/api/javax/json/package-
summary.html
https://docs.oracle.com/javaee/7/tutorial/jsonp.htm
http://www.jcp.org/en/jsr/detail?id=353
http://www.jcp.org/en/jsr/detail?id=374
https://github.com/google/gson
https://github.com/FasterXML/jackson