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。
yaml
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。
sql
==> 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。
java
@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 {
private static final 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。
java
@UtilityClass
public class MybatisUtils {
private static final 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);
} else if (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。
java
@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)
public class MybatisPluginAutoConfiguration {
private final MybatisPluginProperties mybatisPluginProperties;
@Bean
public MybatisSqlLogInterceptor mybatisSqlLogInterceptor() {
MybatisSqlLogInterceptor interceptor = new MybatisSqlLogInterceptor();
interceptor.setSlownessThreshold(mybatisPluginProperties.getSqlLog().getSlownessThreshold());
return interceptor;
}
}
@Data
@ConfigurationProperties(prefix = "mybatis.plugin")
public class MybatisPluginProperties {
private final SqlLog sqlLog = new SqlLog();
@Data
public static class SqlLog {
private boolean 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。
sql
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 eden-mybatis-spring-boot-starter。