Process API

Transcript

1. Properties API Jussi Pohjolainen

2. To store preferences • Simple API to • fetch •

   store • key value pairs

3. import java.io.*; import java.util.*; class Main { public static void

   main(String [] args) throws Exception { Properties prop = new Properties(); // set key and value prop.setProperty("fontSize", "24"); prop.setProperty("fontColor", "RGB(255,255,255)"); String optionalComments = "My preferences file"; prop.store(new FileWriter("./myfile.prop"), optionalComments); } }

4. myfile.prop #My preferences file #Sun Apr 26 10:56:55 EEST 2020

   fontSize=24 fontColor=RGB(255,255,255)

5. Reading import java.io.*; import java.util.*; class Main { public static

   void main(String [] args) throws Exception { Properties prop = new Properties(); prop.load(new FileReader("./myfile.prop")); System.out.println(prop.get("fontSize")); System.out.println(prop.get("fontColor")); } }

6. Storing XML import java.io.*; import java.util.*; class Main { public

   static void main(String [] args) throws Exception { Properties prop = new Properties(); // set key and value prop.setProperty("fontSize", "24"); prop.setProperty("fontColor", "RGB(255,255,255)"); String optionalComments = "My preferences file"; prop.storeToXML(new FileOutputStream("./myfile.xml"), optionalComments); } }

7. myfile.xml <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd"> <properties> <comment>My

   preferences file</comment> <entry key="fontSize">24</entry> <entry key="fontColor">RGB(255,255,255)</entry> </properties>

8. Reading import java.io.*; import java.util.*; class Main { public static

   void main(String [] args) throws Exception { Properties prop = new Properties(); prop.loadFromXML(new FileInputStream("./myfile.xml")); System.out.println(prop.getProperty("fontSize")); System.out.println(prop.getProperty("fontColor")); } }

9. Jackson

10. Jackson • Java classes to json mapping • External class

    library, add dependency • You can use Jackson to save for example preferences file

11. Dependency <dependencies> <dependency> <groupId>com.fasterxml.jackson.core</groupId> <artifactId>jackson-databind</artifactId> <version>2.10.3</version> </dependency> </dependencies>

12. Pojo public class Dog { private String name; public void

    setName(String name) { this.name = name; } public String getName() { return this.name; } }

13. Main import com.fasterxml.jackson.databind.ObjectMapper; import java.io.*; class Main { public static

    void main(String [] args) throws Exception { Dog spot = new Dog(); spot.setName("Spot"); ObjectMapper objectMapper = new ObjectMapper(); objectMapper.writeValue(new File("./file.json"), spot); Dog temp = objectMapper.readValue(new File("./file.json"), Dog.class); System.out.println(temp.getName()); } }