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Mybatis框架中Interceptor接口的使用说明

顺亿
顺亿
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目录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{@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：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：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 > ?)";@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 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pageKey pageKey.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);}}@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

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})@Configuration public class ParamIntecepterAutoConfiguration {@Autowired private List 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脚本之家。

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