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How to write logs into the database with the help of log4j, in view of this problem, this article introduces the corresponding analysis and answers in detail, hoping to help more partners who want to solve this problem to find a more simple and easy way.

Log4j is an excellent open source logging project, we can not only customize the format of the output log, but also define the destination of the log output, such as: screen, text files, data libraries, and even output through socket. This section uses the MySQL database to focus on how to enter log information into the database.

Using log4j to write logs to the database is mainly used in the JDBCAppender class under the log4j package, which provides the function of asynchronously writing log information to the data, we can directly use this class to write our log information to the database; we can also expand the JDBCAppender class, that is, the JDBCAppender class is used as the base class for secondary development to obtain a new subclass with all JDBCAppender class attributes and behaviors.

You can directly use the JDBCAppender class under the log4j package to illustrate how log4j writes log information to the database through an example:

Requirements: in the process of software development, we need to record debugging information, operation information, etc., for later audit, these log information includes user ID, user name, operation class, path, method, operation time, log information.

Design idea: we use JDBCAppender class to insert log information directly into the database, so we only need to configure this kind of information in the configuration file; to get user information, you need to use a filter (if you do not need user information, you do not need to design a filter, in fact, in most cases, you need these user information, especially in the development of web applications). Getting the user information from the log information is achieved through the filter request or session object, but how to transfer the user information to log4j? log4j provides us with MDC, a very useful class in log4j, which is used to store application context information (context Infomation), so that it is easy to use these context information in log. MDC uses a mechanism similar to map to store information, and context information is stored independently by each thread, except that the information is stored in "map" with their key values. The corresponding methods are: "MDC.put (key, value); MDC.remove (key); MDC.get (key);" When configuring PatternLayout, use:% x {key} to output the corresponding value). With MDC, we can first get the user information in the filter, and then use the MDC.Put ("key") method, and log outputs the corresponding value with% x {key} when executing the sql statement.

This is the answer to the question about how to write the log into the database with the help of log4j. I hope the above content can be of some help to you. If you still have a lot of doubts to be solved, you can follow the industry information channel for more related knowledge.

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