实现一个执行 Explain 命令的 Mybatis 插件

package com.lieve.tx.config;
import lombok.extern.slf4j.Slf4j;import org.apache.ibatis.cache.CacheKey;import org.apache.ibatis.executor.Executor;import org.apache.ibatis.mapping.*;import org.apache.ibatis.plugin.*;import org.apache.ibatis.reflection.MetaObject;import org.apache.ibatis.session.ResultHandler;import org.apache.ibatis.session.RowBounds;import org.springframework.stereotype.Component;import org.springframework.util.CollectionUtils;
import java.lang.reflect.Method;import java.sql.ResultSet;import java.sql.Statement;import java.util.ArrayList;import java.util.List;import java.util.Properties;import java.util.regex.Matcher;
/** * @author sunyoboy * 2021/6/13 */@Slf4j@Component@Intercepts({        @Signature(type = Executor.class, method = "query",                args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class}),        @Signature(type = Executor.class, method = "query",                args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class, CacheKey.class, BoundSql.class})})public class MysqlExplainInterceptor implements Interceptor {    @Override    public Object plugin(Object target) {        return Plugin.wrap(target, this);    }
    @Override    public void setProperties(Properties properties) {        // do nothing    }
    @Override    public Object intercept(Invocation invocation) throws Throwable {        Object target = invocation.getTarget();        Object[] args = invocation.getArgs();        if (target instanceof Executor) {            final Executor executor = (Executor) target;            Object parameter = args[1];            boolean isUpdate = args.length == 2;            MappedStatement ms = (MappedStatement) args[0];            if (!isUpdate && ms.getSqlCommandType() == SqlCommandType.SELECT) {                RowBounds rowBounds = (RowBounds) args[2];                ResultHandler resultHandler = (ResultHandler) args[3];                BoundSql boundSql;                if (args.length == 4) {                    boundSql = ms.getBoundSql(parameter);                } else {                    // 几乎不可能走进这里面,除非使用Executor的代理对象调用query[args[6]]                    boundSql = (BoundSql) args[5];                }                String sql = getSql(boundSql, ms);                log.info("sql = {}", sql);                Statement stmt = executor.getTransaction().getConnection().createStatement();                stmt.execute("EXPLAIN " + sql + " ;");                ResultSet rs = stmt.getResultSet();
                List<ExplainResultVo> explainResultList = new ArrayList<>();                while (rs.next()) {                    ExplainResultVo explainResultVo = new ExplainResultVo();                    explainResultVo.setId(rs.getString("id"));                    explainResultVo.setSelectType(rs.getString("select_type"));                    explainResultVo.setTable(rs.getString("table"));                    explainResultVo.setPartitions(rs.getString("partitions"));                    explainResultVo.setType(rs.getString("type"));                    explainResultVo.setPossibleKeys(rs.getString("possible_keys"));                    explainResultVo.setKey(rs.getString("key"));                    explainResultVo.setKeyLen(rs.getString("key_len"));                    explainResultVo.setRef(rs.getString("ref"));                    explainResultVo.setRows(rs.getString("rows"));                    explainResultVo.setFiltered(rs.getString("filtered"));                    explainResultVo.setExtra(rs.getString("Extra"));                    explainResultList.add(explainResultVo);                }
                log.info("*************************** 1. row ***************************");                for (ExplainResultVo resultVo : explainResultList) {                    Method[] methods = resultVo.getClass().getDeclaredMethods();                    for (Method method : methods) {                        if (!method.getName().startsWith("get")) {                            continue;                        }                        Object result = method.invoke(resultVo);                        if (result instanceof String) {                            log.info(method.getName() + " : " + result);                        }                    }                }                log.info("*************************** end ***************************");            }        }        return invocation.proceed();    }
    /**     * 生成要执行的SQL命令     * @param boundSql     * @param ms     * @return     */    private String getSql(BoundSql boundSql, MappedStatement ms) {        String sql = boundSql.getSql();        Object parameterObject = boundSql.getParameterObject();        List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();        if (!CollectionUtils.isEmpty(parameterMappings) && parameterObject != null) {            for (int i = 0; i < parameterMappings.size(); i++) {                ParameterMapping parameterMapping = parameterMappings.get(i);                if (parameterMapping.getMode() != ParameterMode.OUT) {                    //参数值                    Object value;                    //获取参数名称                    String propertyName = parameterMapping.getProperty();                    if (boundSql.hasAdditionalParameter(propertyName)) {                        //获取参数值                        value = boundSql.getAdditionalParameter(propertyName);                    } else if (parameterObject == null) {                        value = null;                    } else if (ms.getConfiguration().getTypeHandlerRegistry().hasTypeHandler(parameterObject.getClass())) {                        //如果是单个值则直接赋值                        value = parameterObject;                    } else {                        MetaObject metaObject = ms.getConfiguration().newMetaObject(parameterObject);                        value = metaObject.getValue(propertyName);                    }                    log.info("value = {}", value);                    sql = sql.replaceFirst("\\?", Matcher.quoteReplacement(getParameter(value)));                }            }
        }        return sql;    }
    public String getParameter(Object parameter) {        if (parameter instanceof String) {            return "'" + parameter.toString() + "'";        }        return parameter.toString();    }}