Reading and writing properties file

What is? properties file ？

properties File is a property file , This kind of document is in the form of key=value Formats store content .Java Can be used in Properties Class to read this file , Use Propertie Class getProperty(key) Method can get the corresponding data . commonly properties Files are stored as some parameters , Make the code more flexible .

Properties File reading ：

Normal read ： utilize BufferInputStream Buffer the input stream for reading , You can read all the contents of the file , But such reading is lost properties The characteristics of the document . This document is based on key=value Formats store content .

Code implementation ：

public class Main {
	public static void main(String[] args) {
		try (BufferedInputStream bis = new BufferedInputStream(new FileInputStream("e:\\IO flow \\data.properties"))) {
			int data =  -1;
			while((data = bis.read())!=-1) {
				System.out.print((char)data);
			}
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

Use Properties Class read ： We need to use load() Methods will “ Input stream ” Load to Properties In the collection object . So that we can base on key To get value Value .
Code implementation ：

public class Main {
	public static void main(String[] args) {
		try ( BufferedInputStream bis = new BufferedInputStream(new FileInputStream("C:\\IO flow \\data.properties"))) {
			Properties props = new Properties();
			props.load(bis); // take “ Input stream ” Load to Properties In the collection object 
			// according to key, obtain value
			System.out.println(props.get("cn"));
			System.out.println(props.get("kr"));
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}
}

 Properties Writing files ：

    First you need to create a Properties object props, Use put() Method to put keys and values into Properties In the collection object , Then you need to use the output stream to pass store() Method to put the temporary data in the set , Persistent write to hard disk for storage .

Code implementation ：

public class Main {
	public static void main(String[] args) {
		//Properties Writing of format file 
		Properties props = new Properties();
		props.put("f1", "2222");
		props.put("f2", "2342");
		// Use output stream , take Properties In the collection KV Key value pair , write in .properties file 
		try (BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream("C:\\IO flow \\demo.properties"))) {
			props.store(bos, "just do it");
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
}