Analyze the log level and usage scenario in Apache Commons Logging

Apache Commons Logging (Commons Logging) is a universal log interface library that provides a standard way to record the log.Commons Logging abstracts different log implementations, such as log4j, java.util.logging, and Apache Log, so that developers can easily switch and configure different log frameworks. In the Commons Logging, the log level determines the important degree of log messages. According to the different levels of important, the log can be divided into different levels.Commons logging defines the following log level: 1. FATAL: The highest -level log message indicates serious errors, which makes the program cannot continue to be executed. 2. ERROR: It means an error occurs, but the program can continue to be executed.For example, open file failure or database connection error. 3. Warn: Indicates potential problems and may cause errors in the program.For example, use outdated APIs or configuration items. 4. Info: The basic operating information for output program can be used to confirm the normal working state of the program. 5. DEBUG: For output detailed debugging information, it can be used for debugging and checking issues. 6. Trace: The minimum log message is used to output the most detailed debugging information, including method calls and variable values. According to different use scenarios, you can flexibly choose the appropriate log level.Generally speaking, the log level can be determined according to the severity and impact scope of the problem.The following are examples of some use scenarios: 1. In the production environment, the log of warn or above is usually used.In this way, potential problems can be discovered in time to avoid serious errors in the program. 2. In the development and testing phase, you can use the Debug or Trace level log according to the need to understand the operating status of the program and find the problem. 3. Use ERROR -level logs when recording abnormal information.By recording error messages and abnormal stacks, the causes of problems can be tracked and analyzed. 4. When you need to pay attention to certain problems but do not hinder the program continue to run, you can use the Info or Warn -level log. Below is a Java code example using Commons logging to record logs: import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; public class ExampleClass { private static final Log log = LogFactory.getLog(ExampleClass.class); public void doSomething() { log.debug("This is a debug message"); log.info("This is an info message"); log.warn("This is a warning message"); log.error("This is an error message"); log.fatal("This is a fatal message"); } } Obtain the `LOG` method by calling the` logFactory.getLog () method, and then you can use the corresponding level log method to record the log according to the need.You can choose the appropriate log level in different methods according to actual needs to achieve appropriate log output.