一、介绍
1、简介
InnerInterceptor 接口是 MyBatis-Plus 提供的一个拦截器接口，用于实现一些常用的 SQL 处理逻辑。
二、API
InnerInterceptor 接口继承自 MyBatis 的 Interceptor 接口，并添加了一些新的方法，用于处理 MyBatis-Plus 的特定功能。
package com.baomidou.mybatisplus.extension.plugins.inner;import java.sql.Connection;
import java.sql.SQLException;
import java.util.Properties;
import org.apache.ibatis.executor.Executor;
import org.apache.ibatis.executor.statement.StatementHandler;
import org.apache.ibatis.mapping.BoundSql;
import org.apache.ibatis.mapping.MappedStatement;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;public interface InnerInterceptor {default boolean willDoQuery(Executor executor, MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {return true;}default void beforeQuery(Executor executor, MappedStatement ms, Object parameter, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) throws SQLException {}default boolean willDoUpdate(Executor executor, MappedStatement ms, Object parameter) throws SQLException {return true;}default void beforeUpdate(Executor executor, MappedStatement ms, Object parameter) throws SQLException {}default void beforePrepare(StatementHandler sh, Connection connection, Integer transactionTimeout) {}default void beforeGetBoundSql(StatementHandler sh) {}default void setProperties(Properties properties) {}
}
willDoQuery: 当执行查询操作时，MyBatis 会调用该方法，判断是否需要执行查询操作。默认返回true，表示继续执行查询操作，如果需要阻止查询操作，则可以在实现该方法时返回false。
beforeQuery: 在执行查询操作之前，MyBatis 会调用该方法。通过实现该方法，可以在查询之前进行一些必要的操作，例如设置数据范围、修改 SQL 等。
willDoUpdate: 当执行更新操作时，MyBatis 会调用该方法，判断是否需要执行更新操作。默认返回true，表示继续执行更新操作，如果需要阻止更新操作，则可以在实现该方法时返回false。
beforeUpdate: 在执行更新操作之前，MyBatis 会调用该方法。通过实现该方法，可以在更新之前进行一些必要的操作，例如设置更新时间、加密数据等。
beforePrepare: 在执行 SQL 之前，MyBatis 会调用该方法。通过实现该方法，可以在 SQL 执行之前进行一些必要的操作，例如设置事务隔离级别、设置查询超时时间等。
beforeGetBoundSql: 在获取 BoundSql 对象之前，MyBatis 会调用该方法。通过实现该方法，可以在获取 BoundSql 对象之前进行一些必要的操作，例如设置参数、修改 SQL 等。
setProperties: 设置拦截器属性。该方法在创建拦截器实例时调用，用于设置拦截器的属性。
pluginExecutor: 在创建 Executor 对象时调用，可以在这里对 Executor 对象进行包装或其他处理。
三、使用方法
1、自定义拦截类
implements Interceptor, InnerInterceptor （1）类头需要有@Intercepts注解；（2）需要重写setProperties方法（方法体为空即可），否则会报错：inherits unrelated defaults for setProperties(Properties) from types org.apache.ibatis.plugin.Interceptor and com.baomidou.mybatisplus.extension.plugins.inner.InnerInterceptor
2、注册
和spring的拦截器org.springframework.web.servlet.HandlerInterceptor 需要注册一样，mybatis的拦截器也需要注册
import com.baomidou.mybatisplus.annotation.DbType;
import com.baomidou.mybatisplus.extension.plugins.MybatisPlusInterceptor;
import com.baomidou.mybatisplus.extension.plugins.inner.BlockAttackInnerInterceptor;
import com.pluscache.demo.interceptor.SqlExplainInterceptor;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;@Configuration
public class MybatisPlusConfig {@Autowiredprivate SqlExplainInterceptor sqlExplainInterceptor;@Beanpublic MybatisPlusInterceptor mybatisPlusInterceptor() {MybatisPlusInterceptor interceptor = new MybatisPlusInterceptor();interceptor.addInnerInterceptor(sqlExplainInterceptor);//interceptor.addInnerInterceptor(xxx);return interceptor;}
}
四、demo
1、执行explain打印结果
@Data
public class ExplainResultVo {private String id;private String selectType;private String table;private String partitions;private String type;private String possibleKeys;private String key;private String keyLen;private String ref;private String rows;private String filtered;private String extra;
}import com.baomidou.mybatisplus.extension.plugins.inner.InnerInterceptor;
import com.pluscache.demo.dto.ExplainResultVo;
import io.micrometer.common.util.StringUtils;
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.Interceptor;
import org.apache.ibatis.plugin.Intercepts;
import org.apache.ibatis.plugin.Invocation;
import org.apache.ibatis.plugin.Signature;
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.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.List;
import java.util.Properties;
import java.util.regex.Matcher;@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 SqlExplainInterceptor implements Interceptor, InnerInterceptor {@Overridepublic void setProperties(Properties properties) {//无需改动}@Overridepublic Object intercept(Invocation invocation) throws Throwable {log.info("进入sql分析");try {Object target = invocation.getTarget();Object[] args = invocation.getArgs();if (target instanceof Executor) {final Executor executor = (Executor) target;Object parameter = args[1];log.info("参数,executor={},parameter={}", executor, parameter);boolean isUpdate = args.length == 2;MappedStatement ms = (MappedStatement) args[0];if (!isUpdate && ms.getSqlCommandType() == SqlCommandType.SELECT){BoundSql boundSql;if (args.length == 4) {boundSql = ms.getBoundSql(parameter);} else {boundSql = (BoundSql) args[5];}String sql = getSql(boundSql, ms);log.info("原来 sql 为 {}", sql);this.handleExplain(executor, sql);return invocation.proceed();}}return invocation.proceed();}catch (Exception e){return invocation.proceed();}}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 (ParameterMapping parameterMapping : parameterMappings) {if (parameterMapping.getMode() != ParameterMode.OUT) {Object value;String propertyName = parameterMapping.getProperty();if (boundSql.hasAdditionalParameter(propertyName)) {value = boundSql.getAdditionalParameter(propertyName);} else if (ms.getConfiguration().getTypeHandlerRegistry().hasTypeHandler(parameterObject.getClass())) {value = parameterObject;} else {MetaObject metaObject = ms.getConfiguration().newMetaObject(parameterObject);value = metaObject.getValue(propertyName);}sql = sql.replaceFirst("\\?", Matcher.quoteReplacement(getParameter(value)));}}}return sql;}public String getParameter(Object parameter) {if (parameter instanceof String) {return "'" + parameter + "'";}return parameter.toString();}private void handleExplain(Executor executor, String sql) throws SQLException {Statement stmt = executor.getTransaction().getConnection().createStatement();stmt.execute("EXPLAIN " + sql + " ;");ResultSet rs = stmt.getResultSet();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"));String rows = rs.getString("rows");explainResultVo.setRows(rows);explainResultVo.setFiltered(rs.getString("filtered"));explainResultVo.setExtra(rs.getString("Extra"));boolean isSimple = "SIMPLE".equals(rs.getString("select_type"));int rowsInt = 0;if (StringUtils.isNotBlank(rows)) {try {rowsInt = Integer.parseInt(rows);} catch (Exception e) {rowsInt = 0;}}log.info("explain语句: {}", explainResultVo);}}
}
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