Basic usage: Properties in JAVA

Basic usage of properties in JAVA

In JAVA development, Properties is a tool class for storing configuration information. It provides a way to convert configuration information into key values. The way to store and access the (key-value) form.

The Properties class inherits from the Hashtable class and only allows keys and values ​​to be string types, and the storage of key-value pairs is unordered.

The Properties class is often used to store application configuration information, such as database connection information, log levels, system properties, etc. In this article, we will introduce the basic usage of the Properties class in detail, with specific code examples.

1. Create Properties object
   Creating a Properties object is very simple, just call its no-argument constructor.

Properties properties = new Properties();

2. Add key-value pairs
   You can use the setProperty() method to add key-value pairs to the Properties object. An example is as follows:

properties.setProperty("db.username", "root");
properties.setProperty("db.password", "123456");

3. Get the value of the key-value pair
   You can use the getProperty() method to get the corresponding value based on the key. If the key does not exist, the getProperty() method will return null.

String username = properties.getProperty("db.username");
String password = properties.getProperty("db.password");

4. Loading configuration information from a file
   The Properties class also provides a load() method to load configuration information from a file. An example is as follows:

FileInputStream fis = new FileInputStream("config.properties");
properties.load(fis);
fis.close();

The above code will open the file named "config.properties" and load the key-value pairs into the Properties object.

5. Save configuration information to a file
   You can use the store() method to save the key-value pairs in the Properties object to a file. An example is as follows:

FileOutputStream fos = new FileOutputStream("config.properties");
properties.store(fos, "This is a config file");
fos.close();

The above code will save the key-value pairs in the Properties object to a file named "config.properties" and add a comment "This is a config file" at the beginning of the file ".

Summary
Through the above code examples, we can see the basic usage of the Properties class in JAVA. It provides a convenient way to store and access configuration information, making our applications more flexible and easier to maintain.

It should be noted that the Properties class may cause garbled characters when processing Chinese characters. To solve this problem, you can use UTF-8 encoding for processing, or use the load() and store() methods with encoding parameters.

In addition, we must also pay attention to exception handling when using the Properties class, such as exception handling such as file non-existence.

To sum up, this article introduces the basic usage of the Properties class in JAVA and comes with specific code examples. I hope it will be helpful for you to use the Properties class during the development process.

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