Mybatis中的插件允许你针对核心组件接口Executor 、StatementHandler、ParameterHandler、ResultSetHandler中任何一个方法进行拦截调用。而每个Interceptor（拦截的接口）其实是通过JDK的动态代理技术生成的代理类，每当执行这4种接口中的方法时，就会进入拦截方法（具体就是InvocationHandler的invoke()方法）。
所以我们要做的就是实现 Interceptor 接口，并指定想要拦截的方法签名。如下示例，拦截的是query和update方法。
/* * MyBatis 将mybatis要执行的sql拦截打印出来 */ @Intercepts ({ @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class}), @Signature(type = Executor.class, method = "update", args = {MappedStatement.class, Object.class}) }) public class SqlPrintInterceptor implements Interceptor {关键是要打印出完整的带参数的SQL。
import java.text.DateFormat; import java.text.SimpleDateFormat; import java.util.Date; import java.util.List; import java.util.Properties; import java.util.regex.Matcher; import org.apache.ibatis.executor.Executor; import org.apache.ibatis.mapping.BoundSql; import org.apache.ibatis.mapping.MappedStatement; import org.apache.ibatis.mapping.ParameterMapping; import org.apache.ibatis.mapping.ParameterMode; import org.apache.ibatis.plugin.Interceptor; import org.apache.ibatis.plugin.Intercepts; import org.apache.ibatis.plugin.Invocation; import org.apache.ibatis.plugin.Plugin; import org.apache.ibatis.plugin.Signature; import org.apache.ibatis.reflection.MetaObject; import org.apache.ibatis.session.Configuration; import org.apache.ibatis.session.ResultHandler; import org.apache.ibatis.session.RowBounds; import org.apache.ibatis.type.TypeHandlerRegistry; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /* * MyBatis 将mybatis要执行的sql拦截打印出来 */ @Intercepts ({ @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class}), @Signature(type = Executor.class, method = "update", args = {MappedStatement.class, Object.class}) }) public class SqlPrintInterceptor implements Interceptor { private static final Logger log = LoggerFactory.getLogger(SqlPrintInterceptor.class); private static final DateFormat DATE_FORMAT = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss"); @Override public Object intercept(Invocation invocation) throws Throwable { MappedStatement mappedStatement = (MappedStatement) invocation.getArgs()[0]; Object parameterObject = null; if (invocation.getArgs().length > 1) { parameterObject = invocation.getArgs()[1]; } long start = System.currentTimeMillis(); Object result = invocation.proceed(); String statementId = mappedStatement.getId(); BoundSql boundSql = mappedStatement.getBoundSql(parameterObject); Configuration configuration = mappedStatement.getConfiguration(); String sql = getSql(boundSql, parameterObject, configuration); long end = System.currentTimeMillis(); long timing = end - start; //根据个人喜好看需要打印怎么sql,本人是打印打印 1s的 if (log.isInfoEnabled() && timing > 1000) { log.info("execl sql spend time:{} ms. dao methods id:{},execl sql is: {}", timing, statementId, sql); } return result; } @Override public Object plugin(Object target) { if (target instanceof Executor) { return Plugin.wrap(target, this); } return target; } @Override public void setProperties(Properties properties) { } private String getSql(BoundSql boundSql, Object parameterObject, Configuration configuration) { String sql = boundSql.getSql().replaceAll("[\\s]+", " "); List<ParameterMapping> parameterMappings = boundSql.getParameterMappings(); TypeHandlerRegistry typeHandlerRegistry = configuration.getTypeHandlerRegistry(); if (parameterMappings != null) { for (int i = 0; i < parameterMappings.size(); i++) { ParameterMapping parameterMapping = parameterMappings.get(i); if (parameterMapping.getMode() != ParameterMode.OUT) { Object value; String propertyName = parameterMapping.getProperty(); if (boundSql.hasAdditionalParameter(propertyName)) { value = boundSql.getAdditionalParameter(propertyName); } else if (parameterObject == null) { value = null; } else if (typeHandlerRegistry.hasTypeHandler(parameterObject.getClass())) { value = parameterObject; } else { MetaObject metaObject = configuration.newMetaObject(parameterObject); value = metaObject.getValue(propertyName); } sql = replacePlaceholder(sql, value); } } } return sql; } private String replacePlaceholder(String sql, Object propertyValue) { String result; if (propertyValue != null) { if (propertyValue instanceof String) { result = "'" + propertyValue + "'"; } else if (propertyValue instanceof Date) { result = "'" + DATE_FORMAT.format(propertyValue) + "'"; } else { result = propertyValue.toString(); } } else { result = "null"; } return sql.replaceFirst("\\?", Matcher.quoteReplacement(result)); } }