Learn about the "logging API" framework principle in the Java class library
Principle of Logging API framework in Java Class Library
Overview:
In modern software development, log records are a vital component that can help developers debug and monitor the operation of applications.The Logging API in the Java class library is a framework for recording logs in Java applications, and is a tool widely used by Java developers.This article will introduce the principles of the logging API framework in the Java class library, including its components, configuration and sample code.
Logging API component:
The logging API framework in the Java class library consists of the following main components:
1. Logger (log recorder): Logger is one of the core components of the Logging API framework. It is used to record log messages.Each logger object is associated with a specific class to classify and manage log messages.
2. Handler (processor): Handler is responsible for receiving log messages generated by logger and processed accordingly.It can output log messages to the console, files, databases, or other goals.Logging API provides multiple predefined Handler implementation, and developers can also achieve custom Handler according to their needs.
3. Formatter: Formatter is used to format the log message into a specific text or XML format to better present and store.Developers can use the default Formatter provided by Logging API, and can also implement custom formatter.
4. Level (log level): Level is used to define the level of log messages.Logging API defines seven levels, from high to low: Severe, Warning, Info, Config, Fine, Finer, and Finest.Developers can set appropriate log levels according to the needs of the application and debugging level.
5. Filter (filter): Filter allows developers to filter out unwanted log messages according to specific conditions.It can filter log messages according to the log recorder, log level and other conditions.
Logging API configuration:
The configuration of the Logging API mainly includes two aspects: configuration file and code configuration.
1. Configuration file: Logging API uses a configuration file called "Logging.properties" to configure the log recorder, processor, formattor, etc.The file should be located under the path of the class.In the configuration file, you can specify the default logging level, the default formator, processor and other attributes.
2. Code configuration: In addition to configuration files, developers can also configure the logging API by programming.Use Java.util. Logging.logmanager class to access the configuration of the logging API, such as setting the global log level, adding a processor, setting formatter, etc.
Example code and configuration:
Below is a simple example code that demonstrates how to use the logging API for logging and configuration.
1. Configure the example file "logging.properties":
handlers= java.util.logging.ConsoleHandler
.level= INFO
java.util.logging.ConsoleHandler.level= INFO
2. Java code example:
import java.util.logging.*;
public class LoggingExample {
private static final Logger logger = Logger.getLogger(LoggingExample.class.getName());
public static void main(String[] args) {
logger.info("This is an information message");
logger.warning("This is a warning message");
}
}
In the above examples, a Logger object is first created, which is associated to the LoggingExample class.Then, two log messages were recorded using Logger's INFO and Warning method.According to the configuration, the log message will be printed to the console.
in conclusion:
The Logging API framework in the Java class library is a powerful and flexible tool for logging in the Java application.This article details the principle of the Logging API framework, including its components, configurations and example code.By using the Logging API, developers can better understand and monitor their application execution situations and make fault investigation and debugging.
