Mybatis框架中Interceptor接口的使用说明 Mybatis框架中Interceptor接口的使

Mybatis Interceptor接口的使用

测试中使用的config文件内容如下
在配置文件中配置了一个Interceptor的实现类

Interceptor修改执行sql及传入参数

总体思路
1、Interceptor 代码实现
2、AutoConfiguration代码实现

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

在配置文件中配置了一个Interceptor的实现类
LogInterceptor的代码如下：

public class LogInterceptor implements Interceptor{@Overridepublic Object intercept(Invocation invocation) throws Throwable {System.out.println("LogInterceptor : intercept"); return null; }@Overridepublic 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; }@Overridepublic 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：

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：

SELECT * FROM city WHERE ID=?

执行的CityMapper如下：

SELECT * FROM city WHERE ID=#{id,jdbcType=INTEGER}

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。

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

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 > ?)"; @Overridepublic 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 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 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 paramIndex) {//处理参数Map 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 paramMap, BoundSql boundSql, CacheKey pageKey, ArrayList paramIndex) {paramMap.put(GLOBALPERIOD, getPeriod()); //处理pageKeypageKey.update(getPeriod()); //处理参数配置handleParameter(boundSql, ms, paramIndex); return paramMap; }protected void handleParameter(BoundSql boundSql, MappedStatement ms,ArrayList paramIndex) {if (boundSql.getParameterMappings() != null) {List 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); }}@Overridepublic Object plugin(Object target) {return Plugin.wrap(target, this); }@Overridepublic void setProperties(Properties properties) {//nothing to do...}}

2、AutoConfiguration代码实现

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 {@Autowiredprivate List sqlSessionFactoryList; public ParamIntecepterAutoConfiguration() {}@PostConstructpublic void addParamInterceptor() {ParamInterceptor interceptor = new ParamInterceptor(); Iterator var3 = this.sqlSessionFactoryList.iterator(); while(var3.hasNext()) {SqlSessionFactory sqlSessionFactory = (SqlSessionFactory)var3.next(); sqlSessionFactory.getConfiguration().addInterceptor(interceptor); }}}

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