The advanced features and skills of the ‘logging API’ framework in the Java library
The advanced features and skills of the ‘logging API’ framework in the Java library
In Java development, log records are a vital task.It can help us track the operation of the application, find problems and debug.Java provides a variety of log record frameworks, the most commonly used is the Logging API.The Logging API framework provides rich functions and configuration options, which can help developers better manage and use log information.
This article will introduce the advanced features and skills of the Logging API framework to help readers better understand and apply the framework.
1. Log level control:
Logging API framework supports multiple logs, including (from low to high): trace, debug, info, warn, error.Each log level has a corresponding log record method, such as `log.trace ()`, `log.debug ()`, `log.info (),` log.warn (), `log.error () `.By setting the appropriate log level, which log messages can be controlled, so that the log has readability and reasonable output.
The following is an example code:
import java.util.logging.Logger;
public class MyClass {
private static final Logger LOGGER = Logger.getLogger(MyClass.class.getName());
public void someMethod() {
// ...
LOGGER.info("This is an informational message.");
LOGGER.warning("This is a warning message.");
// ...
}
}
2. Log formatization:
Logging API allows developers to customize the format of log messages.You can use parameterized messages, use a placeholder to replace the variables, and specify different formatting options, such as the date, time, class name, etc.
The following is an example code:
import java.util.logging.ConsoleHandler;
import java.util.logging.Formatter;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.logging.SimpleFormatter;
public class MyLogger {
private static final Logger LOGGER = Logger.getLogger(MyLogger.class.getName());
public static void main(String[] args) {
ConsoleHandler consoleHandler = new ConsoleHandler();
Formatter formatter = new SimpleFormatter();
consoleHandler.setLevel(Level.ALL);
consoleHandler.setFormatter(formatter);
LOGGER.addHandler(consoleHandler);
LOGGER.log(Level.INFO, "This is a formatted message with {0}", "arguments");
}
}
The output result is: `this is a formatted message with arguments`
3. Logging recorder layered:
Logging API's log recorder can form a hierarchical structure.This can help us group different modules or packages, and make independent log levels and processing program configurations.By setting the level of the parent recorder, the log output of the sub -recorder can be controlled at the same time.
The following is an example code:
import java.util.logging.Level;
import java.util.logging.Logger;
public class ParentLogger {
private static final Logger LOGGER = Logger.getLogger("com.example.ParentLogger");
public static void main(String[] args) {
LOGGER.setLevel(Level.SEVERE);
LOGGER.severe("This is a severe message from the parent logger.");
LOGGER.warning("This is a warning message from the parent logger.");
LOGGER.info("This is an informational message from the parent logger.");
ChildLogger childLogger = new ChildLogger();
childLogger.logMessage();
}
}
class ChildLogger {
private static final Logger LOGGER = Logger.getLogger("com.example.ParentLogger.ChildLogger");
public void logMessage() {
LOGGER.info("This is an informational message from the child logger.");
LOGGER.warning("This is a warning message from the child logger.");
}
}
The output result is:
Mar 09, 2023 12:00:00 AM com.example.ParentLogger logMessage
INFO: This is an informational message from the child logger.
Mar 09, 2023 12:00:00 AM com.example.ParentLogger logMessage
WARNING: This is a warning message from the child logger.
As shown above, by setting up the level of the parent recorder, only the log message of Severe level is output.The logging output of the subwoler will also be affected.
4. Log processing program configuration:
Logging API allows developers to configure different processing programs to process log messages, such as console processing procedures and file processing programs.The processing program can be customized according to the needs of the developer.
The following is an example code:
import java.io.IOException;
import java.util.logging.FileHandler;
import java.util.logging.Level;
import java.util.logging.Logger;
import java.util.logging.SimpleFormatter;
public class MyLogger {
private static final Logger LOGGER = Logger.getLogger(MyLogger.class.getName());
public static void main(String[] args) {
try {
FileHandler fileHandler = new FileHandler("log.txt");
SimpleFormatter formatter = new SimpleFormatter();
fileHandler.setFormatter(formatter);
LOGGER.addHandler(fileHandler);
LOGGER.setLevel(Level.ALL);
LOGGER.log(Level.INFO, "This message will be logged to a file.");
} catch (IOException e) {
LOGGER.log(Level.SEVERE, "Failed to log to file.", e);
}
}
}
In the above example, we are equipped with a file processing program (Filehandler) to save the log message into a file named Log.txt.
The above introduces the advanced features and skills of the Logging API framework.By flexibly applying these functions and configuration options, we can better manage and use log information to improve the reliability and maintenance of applications.
