Real-time monitoring of SQL output in the MyBatis console

MyBatis is a popular persistence layer framework that provides convenient SQL mapping and database operation functions, allowing developers to interact with the database more efficiently. In the actual development process, we sometimes need to print out the SQL statements executed by MyBatis on the console in real time to better debug and optimize SQL queries. This article will introduce how to realize real-time printing of SQL on the console in MyBatis and provide specific code examples.

First, we need to enable the log printing function in the MyBatis configuration file (usually mybatis-config.xml). Add the following configuration to the configuration file:

<configuration>
    <settings>
        <setting name="logImpl" value="STDOUT_LOGGING" />
    </settings>
</configuration>

This configuration item specifies that the log is implemented as a standard output stream (STDOUT_LOGGING), so that the log can be printed to the console.

Next, we need to use the logging framework to capture the SQL statements printed by MyBatis. Here, we will use Log4j as the logging framework. First, add Log4j related dependencies to the project's dependencies:

<dependency>
    <groupId>org.apache.logging.log4j</groupId>
    <artifactId>log4j-core</artifactId>
    <version>2.14.1</version>
</dependency>

Then, create the log4j2.xml configuration file in the project's resource directory, with the following configuration:

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="WARN">
    <Appenders>
        <Console name="Console" target="SYSTEM_OUT">
            <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
        </Console>
    </Appenders>
    <Loggers>
        <Root level="debug">
            <AppenderRef ref="Console" />
        </Root>
    </Loggers>
</Configuration>

An output is configured here Appender to the console and specify the output format.

Finally, we need to intercept and obtain the SQL statement in the MyBatis log, and then print it to the console. Here we can customize a class that implements the org.apache.ibatis.logging.Log interface and implement the logic of printing SQL in it. An example is as follows:

import org.apache.ibatis.logging.Log;
import org.apache.ibatis.logging.LogFactory;

public class ConsoleLogger implements Log {

    private static final Log log = LogFactory.getLog(ConsoleLogger.class);

    @Override
    public boolean isDebugEnabled() {
        return true;
    }

    @Override
    public void error(String s, Throwable e) {
        log.error(s, e);
    }

    @Override
    public void error(String s) {
        log.error(s);
    }

    @Override
    public void debug(String s) {
        log.debug(s);
    }

    @Override
    public void trace(String s) {
        log.trace(s);

        // 打印 SQL 语句到控制台
        System.out.println("SQL: " + s);
    }
}

In this class, we override the methods in the Log interface. When MyBatis prints debug and trace level logs, we extract the SQL statements and print them to the console.

Finally, call the following code to register our custom Logger when the program starts:

import org.apache.ibatis.logging.LogFactory;

public class Main {
    public static void main(String[] args) {
        LogFactory.useCustomLogging(ConsoleLogger.class);
        // Your MyBatis code here
    }
}

Through the above steps, we can print out the SQL statements executed by MyBatis in real time on the console. This is very helpful for debugging and optimizing SQL queries during development. I hope this article will give you the specific implementation of real-time printing of SQL on the MyBatis console, making you more efficient in development!

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