Explore the simple YAML framework technical principles in the Java class library
Simple YAML framework technical principle in the Java class library
YAML (Yaml Ain't Markup Language) is a human friendly data serialization format, and it is also a tag language for configuration files.There are many simple YAML frameworks in the Java library, which can be used to read, analyze and write Yaml files in the Java program.
YAML format uses simple grammar, making configuration files easy to understand and edit.It is mainly composed of key values, lists and nested structures.The following is a simple yaml example:
server:
port: 8080
host: localhost
database:
driver: com.mysql.jdbc.Driver
url: jdbc:mysql://localhost:3306/mydatabase
username: root
password: password123
In Java, the corresponding library needs to be introduced to use the YAML framework.At present, the commonly used Java libraries include Snakeyaml and Jackson.
Snakeyaml is a popular YAML processing class library that provides a simple and easy -to -use API to read and write Yaml files.Below is a sample code for analysis of the above yaml configuration file using Snakeyaml:
import org.yaml.snakeyaml.Yaml;
public class YamlParser {
public static void main(String[] args) {
Yaml yaml = new Yaml();
try (InputStream in = YamlParser.class.getResourceAsStream("config.yaml")) {
Map<String, Object> config = yaml.load(in);
// Read the configuration content
String serverPort = (String) config.get("server.port");
String databaseUrl = (String) config.get("database.url");
// Print configuration content
System.out.println("Server Port: " + serverPort);
System.out.println("Database URL: " + databaseUrl);
} catch (IOException e) {
e.printStackTrace();
}
}
}
This code uses Snakeyaml's `yaml` class to load the Yaml file and analyze it as a` Map` object.You can obtain the value in the configuration file through the method of `config.get (...).Run the above code, the server port and database URL in the configuration file will be output.
Another commonly used Java library is Jackson, which is a powerful data processing class library that supports a variety of data formats, including JSON and YAML.The following is an example code that uses Jackson to analyze and write to the yaml file:
import com.fasterxml.jackson.databind.ObjectMapper;
import com.fasterxml.jackson.dataformat.yaml.YAMLFactory;
public class YamlParser {
public static void main(String[] args) {
ObjectMapper mapper = new ObjectMapper(new YAMLFactory());
try {
// Analyze yaml file
Config config = mapper.readValue(new File("config.yaml"), Config.class);
// Read the configuration content
String serverPort = config.getServer().getPort();
String databaseUrl = config.getDatabase().getUrl();
// Print configuration content
System.out.println("Server Port: " + serverPort);
System.out.println("Database URL: " + databaseUrl);
// Write in yaml file
Config newConfig = new Config();
newConfig.setServer(new Server("8081", "localhost"));
newConfig.setDatabase(new Database("newurl", "username", "password"));
mapper.writeValue(new File("new_config.yaml"), newConfig);
} catch (IOException e) {
e.printStackTrace();
}
}
}
class Config {
private Server server;
private Database database;
// Eliminate the constructor, Getter, and Setter method
}
class Server {
private String port;
private String host;
// Eliminate the constructor, Getter, and Setter method
}
class Database {
private String url;
private String username;
private String password;
// Eliminate the constructor, Getter, and Setter method
}
This code uses Jackson's `ObjectMapper` class and` yamlFactory` class to analyze and write to Yaml files.By defining the corresponding Java class structure, the content of the YAML file is mapped as the Java object.You can obtain the value in the configuration file through the getter method, and you can use the setter method to set the new configuration value.Run the above code, you will read the server port and database URL in the configuration file, and write the new configuration into the new Yaml file.
Through the above example code, we can see the simple YAML framework technical principles in the Java class library.These frameworks provide convenient API and tools, so that the Java program can easily read, analyze, and write to YAML files to achieve the management and use of configuration files.
