MyBatis结合Log4j实现SQL执行时间统计

要实现SQL执行时间统计，可以结合MyBatis和Log4j来实现。首先需要在MyBatis的配置文件中配置Log4j的日志输出，示例如下：

<configuration>    <settings>        <setting name="logImpl" value="LOG4J"/>    </settings>    <properties>        <property name="log4j.rootLogger" value="DEBUG, stdout"/>        <property name="log4j.appender.stdout" value="org.apache.log4j.ConsoleAppender"/>        <property name="log4j.appender.stdout.layout" value="org.apache.log4j.PatternLayout"/>        <property name="log4j.appender.stdout.layout.ConversionPattern" value="%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n"/>    </properties></configuration>

然后在Log4j的配置文件中配置输出格式和日志级别，示例如下：

log4j.rootLogger=DEBUG, stdoutlog4j.appender.stdout=org.apache.log4j.ConsoleAppenderlog4j.appender.stdout.layout=org.apache.log4j.PatternLayoutlog4j.appender.stdout.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss} %-5p %c{1}:%L - %m%n

接着在MyBatis的Mapper接口中使用@Intercepts注解和@Signature注解来实现对SQL执行时间的拦截和统计，示例如下：

@Intercepts({    @Signature(type = Executor.class, method = "update", args = {MappedStatement.class, Object.class}),    @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class})})public class SqlStatsInterceptor implements Interceptor {    @Override    public Object intercept(Invocation invocation) throws Throwable {        long startTime = System.currentTimeMillis();        Object result = invocation.proceed();        long endTime = System.currentTimeMillis();        long time = endTime - startTime;        MappedStatement mappedStatement = (MappedStatement) invocation.getArgs()[0];        String sqlId = mappedStatement.getId();        String sql = mappedStatement.getBoundSql(invocation.getArgs()[1]).getSql();        Logger logger = LoggerFactory.getLogger(SqlStatsInterceptor.class);        logger.info("Execute SQL [{}] cost {}ms", sqlId, time);        return result;    }    @Override    public Object plugin(Object target) {        return Plugin.wrap(target, this);    }    @Override    public void setProperties(Properties properties) {    }}

最后，在MyBatis的配置文件中注册拦截器，示例如下：

<plugins>    <plugin interceptor="com.example.interceptor.SqlStatsInterceptor"/></plugins>

通过以上步骤，就可以实现对SQL执行时间的统计并输出到Log4j日志中。