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背景

MyBatis Plus 通过配置文件中设置 log-impl 属性来指定日志实现，以打印 SQL 语句。

mybatis-plus:
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

logging:
  level:
    org.ylzl.eden.demo.mapper: DEBUG

打印出来的 SQL 内容如下：

==>  Preparing: SELECT id,login,email,activated,locked,lang_key,activation_key,reset_key,reset_date,created_by,created_date,last_modified_by,last_modified_date FROM demo_user WHERE id=?
==> Parameters: 1(Long)
<==  Columns: ID, LOGIN, EMAIL, ACTIVATED, LOCKED, LANG_KEY, ACTIVATION_KEY, RESET_KEY, RESET_DATE, CREATED_BY, CREATED_DATE, LAST_MODIFIED_BY, LAST_MODIFIED_DATE
<==  Row: 1, admin, 1813986321@qq.com, TRUE, FALSE, zh-cn, null, null, null, system, 2025-02-10 22:31:03.818, system, null
<==  Total: 1

然而，默认的日志输出格式存在以下不足：

缺少日志时间，无法快速定位 SQL 执行时间。
SQL 语句可读性差，复杂的 SQL 语句难以阅读。
日志存储成本高：SQL 模板占用较多字符，增加了日志存储成本。

目标

通过 MyBatis 的拦截器实现 SQL 原始语句的打印。

实现

首先，自定义 MyBatis 拦截器，实现 org.apache.ibatis.plugin.Interceptor 接口。

@Intercepts({
@Signature(method = "query", type = Executor.class, args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class}),
 @Signature(method = "query", type = Executor.class, args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class, CacheKey.class, BoundSql.class}),
 @Signature(method = "update", type = Executor.class, args = {MappedStatement.class, Object.class})
})
public class MybatisSqlLogInterceptor implements Interceptor {

privatestaticfinal Logger log = LoggerFactory.getLogger("MybatisSqlLog");

private Duration slownessThreshold = Duration.ofMillis(1000);

@Override
public Object intercept(Invocation invocation) throws Throwable {
  MappedStatement mappedStatement = (MappedStatement) invocation.getArgs()[0];
  String mapperId = mappedStatement.getId();

  String originalSql = MybatisUtils.getSql(mappedStatement, invocation);

long start = SystemClock.now();
  Object result = invocation.proceed();
long duration = SystemClock.now() - start;
        // 当 SQL 执行超过我们设置的阈值，转为 WARN 级别 
if (Duration.ofMillis(duration).compareTo(slownessThreshold) < 0) {
   log.info("{} execute sql: {} ({} ms)", mapperId, originalSql, duration);
  } else {
   log.warn("{} execute sql took more than {} ms: {} ({} ms)", mapperId, slownessThreshold.toMillis(), originalSql, duration);
  }
return result;
 }

@Override
public Object plugin(Object target) {
if (target instanceof Executor) {
   return Plugin.wrap(target, this);
  }
return target;
 }

    // 设置慢 SQL 阈值，单位为秒
public void setSlownessThreshold(Duration slownessThreshold) {
this.slownessThreshold = slownessThreshold;
 }
}

笔者编写了一个工具类负责解析 MyBatis 执行语句，还原为可执行的 SQL 内容。

@UtilityClass
publicclass MybatisUtils {

    privatestaticfinal Pattern PARAMETER_PATTERN = Pattern.compile("\\?");

public String getSql(MappedStatement mappedStatement, Invocation invocation) {
  Object parameter = null;
if (invocation.getArgs().length > 1) {
   parameter = invocation.getArgs()[1];
  }
  BoundSql boundSql = mappedStatement.getBoundSql(parameter);
  Configuration configuration = mappedStatement.getConfiguration();
return resolveSql(configuration, boundSql);
 }

private static String resolveSql(Configuration configuration, BoundSql boundSql) {
  Object parameterObject = boundSql.getParameterObject();
  List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();
  String sql = boundSql.getSql().replaceAll("[\\s]+", " ");
if (!parameterMappings.isEmpty() && parameterObject != null) {
   TypeHandlerRegistry typeHandlerRegistry = configuration.getTypeHandlerRegistry();
   if (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass())) {
    sql = sql.replaceFirst("\\?", Matcher.quoteReplacement(resolveParameterValue(parameterObject)));

   } else {
    MetaObject metaObject = configuration.newMetaObject(parameterObject);
    Matcher matcher = PARAMETER_PATTERN.matcher(sql);
    StringBuffer sqlBuffer = new StringBuffer();
    for (ParameterMapping parameterMapping : parameterMappings) {
     String propertyName = parameterMapping.getProperty();
     Object obj = null;
     if (metaObject.hasGetter(propertyName)) {
      obj = metaObject.getValue(propertyName);
     } elseif (boundSql.hasAdditionalParameter(propertyName)) {
      obj = boundSql.getAdditionalParameter(propertyName);
     }
     if (matcher.find()) {
      matcher.appendReplacement(sqlBuffer, Matcher.quoteReplacement(resolveParameterValue(obj)));
     }
    }
    matcher.appendTail(sqlBuffer);
    sql = sqlBuffer.toString();
   }
  }
return sql;
 }

private static String resolveParameterValue(Object obj) {
if (obj instanceof CharSequence) {
   return"'" + obj + "'";
  }
if (obj instanceof Date) {
   DateFormat formatter = DateFormat.getDateTimeInstance(DateFormat.DEFAULT, DateFormat.DEFAULT, Locale.CHINA);
   return"'" + formatter.format(obj) + "'";
  }
return obj == null ? "" : String.valueOf(obj);
 }
}

将 MyBatis 拦截器设置为 Spring 自动装配。

@AutoConfigureAfter(DataSourceAutoConfiguration.class)
@ConditionalOnBean(SqlSessionFactory.class)
@ConditionalOnProperty(name = "mybatis.plugin.sql-log.enabled")
@EnableConfigurationProperties({MybatisPluginProperties.class})
@RequiredArgsConstructor
@Slf4j
@Role(BeanDefinition.ROLE_INFRASTRUCTURE)
@Configuration(proxyBeanMethods = false)
publicclass MybatisPluginAutoConfiguration {

privatefinal MybatisPluginProperties mybatisPluginProperties;

@Bean
public MybatisSqlLogInterceptor mybatisSqlLogInterceptor() {
  MybatisSqlLogInterceptor interceptor = new MybatisSqlLogInterceptor();
  interceptor.setSlownessThreshold(mybatisPluginProperties.getSqlLog().getSlownessThreshold());
return interceptor;
 }
}

@Data
@ConfigurationProperties(prefix = "mybatis.plugin")
publicclass MybatisPluginProperties {

privatefinal SqlLog sqlLog = new SqlLog();

@Data
publicstaticclass SqlLog {

privateboolean enabled = true;

private Duration slownessThreshold = Duration.ofMillis(1000);
 }
}

当项目配置了属性 mybatis.plugin.sql-log.enabled=true 时，SQL 拦截将生效，打印的内容如下：

2024-02-10 23:03:01.845 INFO  [dev] [XNIO-1 task-1] org.ylzl.eden.demo.infrastructure.user.database.UserMapper.selectById execute sql: SELECT id,login,email,activated,locked,lang_key,activation_key,reset_key,reset_date,created_by,created_date,last_modified_by,last_modified_date FROM demo_user WHERE id=1 (10 ms)

这种日志格式比较符合我们实际的生产要求：提供日志时间、可运行的 SQL、执行耗时。

产出

团队引入这个组件后，在定位生产 SQL 问题时，比原来清晰多了，并且，日志文件缩减了 30% 存储成本。

本文涉及的代码完全开源，感兴趣的伙伴可以查阅：

https://github.com/shiyindaxiaojie/eden-architect/tree/main/eden-components/eden-spring-boot-starters/eden-mybatis-spring-boot-starter

芋道源码 —— 纯源码解析博客

一招搞定！自定义MyBatis拦截器，SQL日志存储成本直降30%

背景

目标

实现

产出