Analysis of log filtration technical principles in logback android framework

LOGBACK Android is a log frame suitable for the Android platform. It provides many functions and features to help developers better manage logs.One of the key features is the log filtering technology. It allows developers to define a set of rules to determine which log messages should be recorded. The log filtering technology in logback android is based on the level settings and filter objects of the Logger instance.Each Logger instance has a level, indicating the lowest level of log messages allowed to record.The log message is divided into multiple levels, such as trace, debug, info, warn and error. The lower the level, the more detailed.Developers can use the logger.setLevel () method to set the level for each logger instance. In addition to level settings, developers can also create custom filter objects to further decide whether to record a log message.Filter objects can use specific rules to match log messages and determine whether to record it according to the matching results.LOGBACK Android provides some built -in filters, such as LevelFilter, EvaluatorFilter, and ThresholdFilter. The following is an example, demonstrating how to use the levelilter filter and logger level to filter log message: import ch.qos.logback.classic.Level; import ch.qos.logback.classic.Logger; import ch.qos.logback.classic.filter.LevelFilter; import org.slf4j.LoggerFactory; public class LogFilterExample { private static final Logger logger = (Logger) LoggerFactory.getLogger(LogFilterExample.class); public static void main(String[] args) { Logger rootLogger = (Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME); LevelFilter filter = new LevelFilter(); filter.setLevel(Level.INFO); filter.setOnMatch(LevelFilter.DENY); filter.start(); rootLogger.addAppender(filter); // Set the level of logger logger.setLevel(Level.DEBUG); logger.trace("This is a trace message."); logger.debug("This is a debug message."); logger.info("This is an info message."); } } In the above example, we create a levelIlter object and set its level to INFO.Then we refuse to record the log message that matches the level by calling the Filter.Setonmatch () method.Finally, we add the filter to the APPENDER of Logger. For the Logger instance, we set its level to Debug, which means that it is recorded only when the log level is higher than the debug.In our examples, the log messages of Trace and Debug levels will not be recorded because they are lower than the level of Logger.The Info -level log message is allowed to record because it matches the level settings of the filter. In this way, we can define the filtering rules according to our own needs, so as to filter out unwanted log messages and record qualified log messages.This helps improve the readability and maintenance of the log, while reducing the size of the log file.