1. Exporting and Importing Data
JSON
Exporting and Importing Data
JSON
SoftUni Team
Technical Trainers
Software University
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2. Table of Contents JSON Export JSON Import *
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3. Questions
sli.do #db-advanced

4. JSON

5. JSON Specifics JSON = JavaScript Object Notation
JSON is a subset of JavaScript syntax
JSON is a lightweight format that is used for data interchanging
JSON is easy to read and write
JSON is language independent
JSON format is primarily used to transmit data between a server and web application
The filename extension is .json

6. JSON Example person.json js object Key Value Variable Value Property {
"firstName": "Daniel",
"lastName": "Sempre",
"age": 24,
"isMarried": true }
js object
Variable
Value
var person = {
firstName: "Daniel",
lastName: "Sempre",
age: 24,
isMarried: true };
Property

7. JSON Function Client Server person.js person.json car.js car.json
JavaScript
Java, PHP, C#
Client
Server
JSON
PersonController.java
person.js
person.json
CarController.java
car.js
car.json

8. JSON Structure Data is represented in name/value pairs.
Curly braces hold objects
Square brackets hold arrays
person.json
Object holder
Key
Value {
"firstName": "Daniel",
"lastName": "Sempre",
"age": 24,
"isMarried": true }
Comma separeted

9. Nested array of objects
JSON Structure
Object holder
person.json
Key
Value {
"firstName": "John",
"lastName": "Snow",
"address": {
"country": "Spain",
"city": "Barcelona",
"street": "Barcelona" },
"phoneNumbers": [
"number": "1e341341"
"number": "542152" } ]
Nested object
Nested array of objects
Array holder

10. JSON Data Types Type Description Number
double- precision floating-point
String
double-quoted Unicode
Boolean
true or false
Array
an ordered sequence of values
Object
an unordered collection of key:value pairs
null
empty

11. GSON
Provide easy to use mechanisms to convert Java to JSON and vice-versa
Generate compact and readability JSON output
pom.xml
<dependency>
<groupId>com.google.code.gson</groupId>
<artifactId>gson</artifactId>
</dependency>

12. GSON Initialization
Gson objects are responsible for the JSON manipulations
GsonBuilder creates an instance of GSON
excludeFieldsWithoutExposeAnnotation() – excludes fields without @Expose annotation
setPrettyPrinting() – justifies the JSON
create() – creates an instance of Gson
JsonParser.java
Gson gson = new GsonBuilder()
.excludeFieldsWithoutExposeAnnotation()
.setPrettyPrinting()
.create();

13. Export Single Object to JSON
AddressJsonDto.java
The filed will be imported/exported
public class AddressJsonDto implements Serializable {
@Expose
private String country;
private String city;
private String street; }
JsonParser.java
AddressJsonDto addressJsonDto = new AddressJsonDto();
addressJsonDto.setCountry("Bulgaria");
addressJsonDto.setCity("Sofia");
addressJsonDto.setStreet("Mladost 4"); String content = this.gson.toJson(addressJsonDto);
Creates JSON

14. Export Single Object to JSON
JsonParser.java
AddressJsonDto addressJsonDto = new AddressJsonDto();
addressJsonDto.setCountry("Bulgaria");
addressJsonDto.setCity("Sofia");
addressJsonDto.setStreet("Mladost 4"); String content = this.gson.toJson(addressJsonDto);
address.json {
"country": "Bulgaria",
"city": "Sofia",
"street": "Mladost 4" }

15. Export Multiple Object to JSON
JsonParser.java
List<AddressJsonDto> addressJsonDtos = new ArrayList<>();
addressJsonDtos.add(addressJsonDtoBulgaria);
addressJsonDtos.add(addressJsonDtoSpain);
String content = this.gson.toJson(addressJsonDtos);
addresses.json [ {
"country": "Bulgaria",
"city": "Sofia",
"street": "Mladost 4" },
"country": "Spain",
"city": "Barcelona",
"street": "Las Ramblas" } ]

16. Import Single Object to JSON
AddressJsonDto.java
The filed will be imported/exported
public class AddressJsonDto implements Serializable {
@Expose
private String country;
private String city;
private String street; }
JsonParser.java
Creates Object
AddressJsonDto addressJsonDto =
this.gson.fromJson(AddressJsonDto.class, "/files/input/json/address.json");

17. Import Single Object to JSON
AddressJsonDto.java
public class AddressJsonDto implements Serializable {
@Expose
private String country;
private String city;
private String street; }
address.json {
"country": "Bulgaria",
"city": "Sofia",
"street": "Mladost 4" }

18. Import Multiple Object to JSON
JsonParser.java
Object Array
AddressJsonDto[] addressJsonDtos =
this.gson.fromJson(AddressJsonDto[].class, "/files/input/json/addresses.json");
addresses.json [ {
"country": "Bulgaria",
"city": "Sofia",
"street": "Mladost 4" },
"country": "Spain",
"city": "Barcelona",
"street": "Las Ramblas" } ]

19. Summary
JSON Export
JSON Import

20. JSON https://softuni.bg/courses/databases-advanced-hibernate
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21. License
This course (slides, examples, demos, videos, homework, etc.) is licensed under the "Creative Commons Attribution- NonCommercial-ShareAlike 4.0 International" license
Attribution: this work may contain portions from
"Databases" course by Telerik Academy under CC-BY-NC-SA license
© Software University Foundation –
This work is licensed under the Creative Commons Attribution-NonCommercial-ShareAlike license.

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