Mybatis Interceptor接口的使用
关于Mybatis中插件的声明需要在configuration的配置文件中进行配置，配置文件的位置使用configLocation属性指定。
测试中使用的config文件内容如下
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<?xml version="1.0" encoding="UTF-8" ?><!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"><configuration> <!--plugins插件之 分页拦截器 --> <plugins> <plugin interceptor="com.interceptors.LogInterceptor" ></plugin> </plugins></configuration> |
在配置文件中配置了一个Interceptor的实现类
LogInterceptor的代码如下：
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public class LogInterceptor implements Interceptor{ @Override public Object intercept(Invocation invocation) throws Throwable { System.out.println("LogInterceptor : intercept"); return null; } @Override public Object plugin(Object target) { if(target instanceof StatementHandler){ RoutingStatementHandler handler = (RoutingStatementHandler)target; //打印出当前执行的sql语句 System.out.println(handler.getBoundSql().getSql()); } return target; } @Override public void setProperties(Properties properties) { System.out.println("LogInterceptor : setProperties"); }} |
在工程的配置文件中，在配置SqlSessionFactoryBean时需要指明config配置文件的位置，配置文件如下：
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<?xml version="1.0" encoding="UTF-8"?><beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd"> <bean id="user1" class="com.beans.User"> <property name="userName" value="zhuyuqiang"/> </bean> <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource"> <property name="name" value="mysql"/> <property name="url" value="jdbc:mysql://127.0.0.1:3306/world"/> <property name="username" value="root"/> <property name="password" value="zh4y4q5ang"/> <property name="driverClassName" value="com.mysql.jdbc.Driver"/> </bean> <bean id="sqlSessionFactory" class="org.mybatis.spring.SqlSessionFactoryBean"> <property name="dataSource" ref="dataSource"/> <property name="mapperLocations" value="classpath:mybatis/*.xml"/> <property name="typeAliasesPackage" value="com.entities"/> <property name="configLocation" value="classpath:config/configuration.xml"/> </bean> <bean id="mapperScannerConfigurer" class="org.mybatis.spring.mapper.MapperScannerConfigurer"> <property name="basePackage" value="com.interfaces"/> </bean> <bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager"> <property name="dataSource" ref="dataSource"/> </bean> <context:component-scan base-package="com"/></beans> |
基本上这样配置以后，在工程中声明的plugin就已经生效了，实际中打印出来的log如下：
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SELECT * FROM city WHERE ID=? |
执行的CityMapper如下：
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<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd"><mapper namespace="com.interfaces.CityMapper"><resultMap id="BaseResultMap" type="com.entities.City"> <id column="ID" jdbcType="INTEGER" property="id"/> <result column="Name" jdbcType="CHAR" property="name"/> <result column="CountryCode" jdbcType="CHAR" property="countrycode"/> <result column="District" jdbcType="CHAR" property="district"/> <result column="Population" jdbcType="INTEGER" property="population"/></resultMap><select id="selectCityById" parameterType="int" resultType="com.entities.City"> SELECT * FROM city WHERE ID=#{id,jdbcType=INTEGER}</select></mapper> |
简单的测试了一下，可以打印出sql语句。在使用mybatis提供的plugin接口时需要注意，在构建ParameterHandler 、ResultSetHandler 、StatementHandler 和Executor 的时候都会调用在项目中实现的插件接口，一般情况下，如果只是为了打印显示当前执行的sql语句，可以只在当target为StatementHandler类型的时候再进行处理即可。
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public ParameterHandler newParameterHandler(MappedStatement mappedStatement, Object parameterObject, BoundSql boundSql) { ParameterHandler parameterHandler = mappedStatement.getLang().createParameterHandler(mappedStatement, parameterObject, boundSql); parameterHandler = (ParameterHandler) interceptorChain.pluginAll(parameterHandler); return parameterHandler;}public ResultSetHandler newResultSetHandler(Executor executor, MappedStatement mappedStatement, RowBounds rowBounds, ParameterHandler parameterHandler, ResultHandler resultHandler, BoundSql boundSql) { ResultSetHandler resultSetHandler = new DefaultResultSetHandler(executor, mappedStatement, parameterHandler, resultHandler, boundSql, rowBounds); resultSetHandler = (ResultSetHandler) interceptorChain.pluginAll(resultSetHandler); return resultSetHandler;}public StatementHandler newStatementHandler(Executor executor, MappedStatement mappedStatement, Object parameterObject, RowBounds rowBounds, ResultHandler resultHandler, BoundSql boundSql) { System.out.println("newStatementHandler......"); StatementHandler statementHandler = new RoutingStatementHandler(executor, mappedStatement, parameterObject, rowBounds, resultHandler, boundSql); statementHandler = (StatementHandler) interceptorChain.pluginAll(statementHandler); return statementHandler;}public Executor newExecutor(Transaction transaction) { return newExecutor(transaction, defaultExecutorType);}public Executor newExecutor(Transaction transaction, ExecutorType executorType) { executorType = executorType == null ? defaultExecutorType : executorType; executorType = executorType == null ? ExecutorType.SIMPLE : executorType; Executor executor; if (ExecutorType.BATCH == executorType) { executor = new BatchExecutor(this, transaction); } else if (ExecutorType.REUSE == executorType) { executor = new ReuseExecutor(this, transaction); } else { executor = new SimpleExecutor(this, transaction); } if (cacheEnabled) { executor = new CachingExecutor(executor); } executor = (Executor) interceptorChain.pluginAll(executor); return executor;} |
在实际测操作中，在项目中定义实现的plugin都会被添加保存到interceptorChain对象的一个集合中，在内部会对集合里的对象进行遍历，分别调用每个插件的plugin方法。
其中target就是在调用pluginAll传入的具体对象。。。
Interceptor修改执行sql及传入参数
项目中途遇到业务需求更改，在查询某张表时需要增加条件，由于涉及的sql语句多而且依赖其他服务的jar，逐个修改sql语句和接口太繁杂。项目使用mybatis框架，因此借鉴PageHelper插件尝试使用mybatis的Interceptor来实现改需求。
总体思路
- 从BoundSql中获取sql，通过正则匹配替换表名为子查询REPLACE_TXT
- 添加子查询REPLACE_TXT 中需要用到的参数到mybatis参数列表中
- 添加参数与占位符映射，即添加ParameterMapping对象到ParameterMappings中，由于statement在执行时是按照ParameterMappings的元素索引定位占位符封装参数（即ParameterMappings中的第一个参数会封装到第一个占位符上），因此ParameterMappings中的参数顺序需要和占位符保持一致。其次ParameterMappings的元素个数需要和占位符个数保持一致。
- 为了保证该intercept在最后执行，使用AutoConfiguration将intercept添加到SqlSessionFactory的Configuration中，并在spring.factories文件中添加AutoConfiguration
- 未测试性能以及是否存在未知缺陷
1、Interceptor 代码实现
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package org.cnbi.project.other.sql.intercept;import cn.hutool.core.util.NumberUtil;import com.cnbi.cloud.common.core.exception.ServiceException;import com.github.pagehelper.Page;import com.github.pagehelper.util.ExecutorUtil;import com.github.pagehelper.util.MetaObjectUtil;import org.apache.ibatis.builder.annotation.ProviderSqlSource;import org.apache.ibatis.cache.CacheKey;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.plugin.*;import org.apache.ibatis.reflection.MetaObject;import org.apache.ibatis.session.ResultHandler;import org.apache.ibatis.session.RowBounds;import org.cnbi.project.other.sql.aop.PeriodHolder;import java.util.*;import java.util.regex.Matcher;import java.util.regex.Pattern;/** * @ClassName ParamInterceptor * @Description 修改接口太繁琐，直接用mybatis拦截器对查询sql进行拦截，将期间参数注入sql * @Author Wangjunkai * @Date 2019/10/23 11:36 **/@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 ParamInterceptor implements Interceptor { private final static Pattern DW_DIMCOMPANY = Pattern.compile("dw_dimcompany", Pattern.CASE_INSENSITIVE); private final static String REPLACE_TXT = "(select * from dw_dimcompany where cisdel = '0' and START_PERIOD <= ? and END_PERIOD > ?)"; @Override public Object intercept(Invocation invocation) throws Throwable { Object[] args = invocation.getArgs(); MappedStatement ms = (MappedStatement) args[0]; Object parameter = args[1]; RowBounds rowBounds = (RowBounds) args[2]; ResultHandler resultHandler = (ResultHandler) args[3]; Executor executor = (Executor) invocation.getTarget(); CacheKey cacheKey; BoundSql boundSql; if(args.length == 4){ boundSql = ms.getBoundSql(parameter); } else { boundSql = (BoundSql) args[5]; } //获取sql语句，使用正则忽略大小写匹配 String sql = boundSql.getSql(); Matcher matcher = DW_DIMCOMPANY.matcher(sql); //没有需要替换的表名则放行 if(!matcher.find()){ return invocation.proceed(); } //收集占位符个数（即paramIndex 的size）以及占位符次序（slot：即参数在ParameterMappings中的顺序） int index = 0; ArrayList<Integer> paramIndex = new ArrayList<>(); while(matcher.find(index)){ index = matcher.end(); String sqlPart = sql.substring(0, index); int slot = index - sqlPart.replace("?", "").length() + paramIndex.size() ; paramIndex.add(slot); paramIndex.add(slot + 1); } //替换子查询 String companyPeriodSql = matcher.replaceAll(REPLACE_TXT); cacheKey = args.length == 4 ? executor.createCacheKey(ms, parameter, rowBounds, boundSql) : (CacheKey) args[4]; //处理参数 Object parameterObject = processParameterObject(ms, parameter, boundSql, cacheKey, paramIndex); BoundSql companyPeriodBoundSql = new BoundSql(ms.getConfiguration(), companyPeriodSql, boundSql.getParameterMappings(), parameterObject); Map<String, Object> additionalParameters = ExecutorUtil.getAdditionalParameter(boundSql); //设置动态参数 for (String key : additionalParameters.keySet()) { companyPeriodBoundSql.setAdditionalParameter(key, additionalParameters.get(key)); } return executor.query(ms, parameterObject, RowBounds.DEFAULT, resultHandler, cacheKey, companyPeriodBoundSql); } public Object processParameterObject(MappedStatement ms, Object parameterObject, BoundSql boundSql, CacheKey pageKey, ArrayList<Integer> paramIndex) { //处理参数 Map<String, Object> paramMap = null; if (parameterObject == null) { paramMap = new HashMap<>(); } else if (parameterObject instanceof Map) { //解决不可变Map的情况 paramMap = new HashMap<>(); paramMap.putAll((Map) parameterObject); } else { paramMap = new HashMap<>(); // sqlSource为ProviderSqlSource时，处理只有1个参数的情况 if (ms.getSqlSource() instanceof ProviderSqlSource) { String[] providerMethodArgumentNames = ExecutorUtil.getProviderMethodArgumentNames((ProviderSqlSource) ms.getSqlSource()); if (providerMethodArgumentNames != null && providerMethodArgumentNames.length == 1) { paramMap.put(providerMethodArgumentNames[0], parameterObject); paramMap.put("param1", parameterObject); } } //动态sql时的判断条件不会出现在ParameterMapping中，但是必须有，所以这里需要收集所有的getter属性 //TypeHandlerRegistry可以直接处理的会作为一个直接使用的对象进行处理 boolean hasTypeHandler = ms.getConfiguration().getTypeHandlerRegistry().hasTypeHandler(parameterObject.getClass()); MetaObject metaObject = MetaObjectUtil.forObject(parameterObject); //需要针对注解形式的MyProviderSqlSource保存原值 if (!hasTypeHandler) { for (String name : metaObject.getGetterNames()) { paramMap.put(name, metaObject.getValue(name)); } } //下面这段方法，主要解决一个常见类型的参数时的问题 if (boundSql.getParameterMappings() != null && boundSql.getParameterMappings().size() > 0) { for (ParameterMapping parameterMapping : boundSql.getParameterMappings()) { String name = parameterMapping.getProperty(); if (!name.equals(GLOBALPERIOD) && paramMap.get(name) == null) { if (hasTypeHandler || parameterMapping.getJavaType().equals(parameterObject.getClass())) { paramMap.put(name, parameterObject); break; } } } } } return processPageParameter(ms, paramMap, boundSql, pageKey, paramIndex); } private final static String GLOBALPERIOD = "globalPeriod"; public Object processPageParameter(MappedStatement ms, Map<String, Object> paramMap, BoundSql boundSql, CacheKey pageKey, ArrayList<Integer> paramIndex) { paramMap.put(GLOBALPERIOD, getPeriod()); //处理pageKey pageKey.update(getPeriod()); //处理参数配置 handleParameter(boundSql, ms, paramIndex); return paramMap; } protected void handleParameter(BoundSql boundSql, MappedStatement ms, ArrayList<Integer> paramIndex) { if (boundSql.getParameterMappings() != null) { List<ParameterMapping> newParameterMappings = new ArrayList<>(boundSql.getParameterMappings()); for (Integer index : paramIndex) { if(index < newParameterMappings.size()) { newParameterMappings.add(index, new ParameterMapping.Builder(ms.getConfiguration(), GLOBALPERIOD, String.class).build()); }else{ newParameterMappings.add(new ParameterMapping.Builder(ms.getConfiguration(), GLOBALPERIOD, String.class).build()); } } MetaObject metaObject = MetaObjectUtil.forObject(boundSql); metaObject.setValue("parameterMappings", newParameterMappings); } } private final static String Q = "Q"; private final static String H = "H"; private String getPeriod(){ //使用threadlocal保存从request中获取的参数，此处不再描述 String period = PeriodHolder.getPeriod(); if(NumberUtil.isNumber(period)){ return period; }else if(period.contains(Q)){ return period.substring(0, 4) + Integer.parseInt(period.substring(5)) * 3; }else if(period.contains(H)){ return period.substring(0, 4) + Integer.parseInt(period.substring(5)) * 6; }else{ throw new ServiceException("非法期间:" + period); } } @Override public Object plugin(Object target) { return Plugin.wrap(target, this); } @Override public void setProperties(Properties properties) { //nothing to do... }} |
2、AutoConfiguration代码实现
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package org.cnbi.project.autoconfig;import com.github.pagehelper.autoconfigure.PageHelperAutoConfiguration;import org.apache.ibatis.session.SqlSessionFactory;import org.cnbi.project.other.sql.intercept.ParamInterceptor;import org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.autoconfigure.AutoConfigureAfter;import org.springframework.context.annotation.Configuration;import javax.annotation.PostConstruct;import java.util.Iterator;import java.util.List;/** * @ClassName ParamIntecepterAutoConfiguration * @Description * @Author Wangjunkai * @Date 2019/10/23 15:41 **/@AutoConfigureAfter({MybatisAutoConfiguration.class, PageHelperAutoConfiguration.class})@Configurationpublic class ParamIntecepterAutoConfiguration { @Autowired private List<SqlSessionFactory> sqlSessionFactoryList; public ParamIntecepterAutoConfiguration() { } @PostConstruct public void addParamInterceptor() { ParamInterceptor interceptor = new ParamInterceptor(); Iterator var3 = this.sqlSessionFactoryList.iterator(); while(var3.hasNext()) { SqlSessionFactory sqlSessionFactory = (SqlSessionFactory)var3.next(); sqlSessionFactory.getConfiguration().addInterceptor(interceptor); } }} |
以上为个人经验，希望能给大家一个参考，也希望大家多多支持服务器之家。
原文链接：https://blog.csdn.net/u011043551/article/details/80625167
