拦截器 - 【4】拦截器实例2 - 《Mybatis》

其中包含如下几个要点：获取mappedStatement、boundSql和重置mappedStatement。
/*
 *      Copyright (c) 2018-2028, Chill Zhuang All rights reserved.
 *
 *  Redistribution and use in source and binary forms, with or without
 *  modification, are permitted provided that the following conditions are met:
 *
 *  Redistributions of source code must retain the above copyright notice,
 *  this list of conditions and the following disclaimer.
 *  Redistributions in binary form must reproduce the above copyright
 *  notice, this list of conditions and the following disclaimer in the
 *  documentation and/or other materials provided with the distribution.
 *  Neither the name of the dreamlu.net developer nor the names of its
 *  contributors may be used to endorse or promote products derived from
 *  this software without specific prior written permission.
 *  Author: Chill 庄骞 (smallchill@163.com)
 */
package org.springblade.core.mp.plugins;
import com.baomidou.mybatisplus.extension.parser.JsqlParserSupport;
import lombok.extern.slf4j.Slf4j;
import net.sf.jsqlparser.expression.operators.relational.EqualsTo;
import net.sf.jsqlparser.parser.CCJSqlParserUtil;
import net.sf.jsqlparser.schema.Column;
import net.sf.jsqlparser.schema.Table;
import net.sf.jsqlparser.statement.Statement;
import net.sf.jsqlparser.statement.select.Join;
import net.sf.jsqlparser.statement.select.PlainSelect;
import net.sf.jsqlparser.statement.select.Select;
import net.sf.jsqlparser.statement.select.SelectBody;
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.SqlCommandType;
import org.apache.ibatis.mapping.SqlSource;
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.DefaultReflectorFactory;
import org.apache.ibatis.reflection.MetaObject;
import org.apache.ibatis.reflection.factory.DefaultObjectFactory;
import org.apache.ibatis.reflection.wrapper.DefaultObjectWrapperFactory;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
import org.springblade.core.mp.annotation.SqlAssets;
import org.springframework.stereotype.Component;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.sql.SQLException;
import java.util.Collections;
import java.util.Properties;
/**
 * 租户拦截器
 *
 * @author Chill
 */
@Slf4j
@Intercepts({
    @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class, CacheKey.class, BoundSql.class}),
    @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class})
})
@Component
public class CdosAssetInterceptor extends JsqlParserSupport implements Interceptor {
    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        // 获取拦截的参数
        Object[] args = invocation.getArgs();
        MappedStatement mappedStatement = (MappedStatement) args[0];
        // 如果不是select方法，则继续执行
        if (!SqlCommandType.SELECT.equals(mappedStatement.getSqlCommandType())) {
            return invocation.proceed();
        }
        // 获取执行方法的包名和方法名
        String namespace = mappedStatement.getId();
        String className = namespace.substring(0, namespace.lastIndexOf("."));
        String methodName = namespace.substring(namespace.lastIndexOf(".") + 1, namespace.length());
        Method[] methods = Class.forName(className).getMethods();
        SqlAssets annotation = null;
        for (Method method : methods) {
            if (method.getName().equals(methodName)) {
                //获取注解  来判断是不是要储存sql
                annotation = method.getAnnotation(SqlAssets.class);
                break;
            }
        }
        if (annotation != null) {
            // 获得关联的参数
            String tableName = annotation.tableName();
            String fieldName = annotation.fieldName();
            // 获取调用方法的参数列表
            Object parameter = null;
            if (args.length > 1) {
                parameter = args[1];
            }
            BoundSql boundSql = mappedStatement.getBoundSql(parameter);
//            PluginUtils.MPBoundSql mpBs = PluginUtils.mpBoundSql(boundSql);
            String originalSql = boundSql.getSql();
            Object parameterObject = boundSql.getParameterObject();
//            mpBs.sql(parserSingle(mpBs.sql(), null));
            log.info("");
            if (parameterObject != null) {
                // 解析Sql
                Statement statement = CCJSqlParserUtil.parse(originalSql);
                SelectBody selectBody = ((Select) statement).getSelectBody();
                PlainSelect plainSelect = (PlainSelect) selectBody;
                // todo: 字段冲突，新加的tb_asset表如果和旧表字段冲突怎么办
                // 修改joins
                Table assetTable = new Table("tb_asset");
                Table oldTable = new Table(tableName);
                Join join = new Join();
                join.setInner(true);
                join.setRightItem(assetTable);
                EqualsTo equalsTo = new EqualsTo();
                equalsTo.setLeftExpression(new Column(assetTable, "id"));
                equalsTo.setRightExpression(new Column(oldTable, fieldName));
                join.setOnExpression(equalsTo);
                if (plainSelect.getJoins() != null) {
                    plainSelect.getJoins().add(join);
                } else {
                    plainSelect.setJoins(Collections.singletonList(join));
                }
                String newSql = statement.toString();
                resetSql2Invocation(invocation, newSql);
            }
        }
//        List<ParameterMapping> parameterMappings = boundSql.getParameterMappings();
//        Class<?>[] parameterClasses = parameterMappings.parallelStream().map(ParameterMapping::getJavaType).toArray(Class<?>[]::new);
//        // 获取方法
//        Class<?> aClass = Class.forName(className);
//        Method method = aClass.getMethod(methodName, parameterClasses);
        return invocation.proceed();
    }
    @Override
    public Object plugin(Object target) {
        return Interceptor.super.plugin(target);
    }
    @Override
    public void setProperties(Properties properties) {
        Interceptor.super.setProperties(properties);
    }
    /**
     * 包装sql后，重置到invocation中
     *
     * @param invocation
     * @param sql
     * @throws SQLException
     */
    private void resetSql2Invocation(Invocation invocation, String sql) throws SQLException {
        final Object[] args = invocation.getArgs();
        MappedStatement statement = (MappedStatement) args[0];
        Object parameterObject = args[1];
        BoundSql boundSql = statement.getBoundSql(parameterObject);
        MappedStatement newStatement = newMappedStatement(statement, new BoundSqlSqlSource(boundSql));
        MetaObject msObject = MetaObject.forObject(newStatement, new DefaultObjectFactory(), new DefaultObjectWrapperFactory(), new DefaultReflectorFactory());
        msObject.setValue("sqlSource.boundSql.sql", sql);
        args[0] = newStatement;
    }
    private MappedStatement newMappedStatement(MappedStatement ms, SqlSource newSqlSource) {
        MappedStatement.Builder builder =
            new MappedStatement.Builder(ms.getConfiguration(), ms.getId(), newSqlSource, ms.getSqlCommandType());
        builder.resource(ms.getResource());
        builder.fetchSize(ms.getFetchSize());
        builder.statementType(ms.getStatementType());
        builder.keyGenerator(ms.getKeyGenerator());
        if (ms.getKeyProperties() != null && ms.getKeyProperties().length != 0) {
            StringBuilder keyProperties = new StringBuilder();
            for (String keyProperty : ms.getKeyProperties()) {
                keyProperties.append(keyProperty).append(",");
            }
            keyProperties.delete(keyProperties.length() - 1, keyProperties.length());
            builder.keyProperty(keyProperties.toString());
        }
        builder.timeout(ms.getTimeout());
        builder.parameterMap(ms.getParameterMap());
        builder.resultMaps(ms.getResultMaps());
        builder.resultSetType(ms.getResultSetType());
        builder.cache(ms.getCache());
        builder.flushCacheRequired(ms.isFlushCacheRequired());
        builder.useCache(ms.isUseCache());
        return builder.build();
    }
    // 定义一个内部辅助类，作用是包装sql
    class BoundSqlSqlSource implements SqlSource {
        private BoundSql boundSql;
        public BoundSqlSqlSource(BoundSql boundSql) {
            this.boundSql = boundSql;
        }
        @Override
        public BoundSql getBoundSql(Object parameterObject) {
            return boundSql;
        }
    }
}