作者：京东科技 李俊龙

一、使用方式

数据权限控制需要对查询出的数据进行筛选，对业务入侵最少的方式就是利用mybatis或者数据库连接池的切片对已有业务的sql进行修改。切片逻辑完成后，仅需要在业务中加入少量标记代码，就可以实现对数据权限的控制。这种修改方式，对老业务的逻辑没有入侵或只有少量入侵，基本不影响老业务的逻辑和可读性；对新业务，业务开发人员无需过多关注权限问题，可以集中精力处理业务逻辑。

由于部门代码中使用的数据库连接池种类较多，不利于切片控制逻辑的快速完成，而sql拼接的部分基本只有mybatis和java字符串直接拼接两种方式，因此使用mybatis切片的方式来完成数据权限控制逻辑。在mybatis的mapper文件的接口上添加注解，注解中写明需要控制的权限种类、要控制的表名、列名即可控制接口的数据权限。

由于mybatis的mapper文件中的同一接口在多个地方被调用，有的需要控制数据权限，有的不需要，因此增加一种权限控制方式：通过ThreadLocal传递权限控制规则来控制当前sql执行时控制数据权限。

权限控制规则格式如下：

限权规则code1(表名1.字段名1,表名2.字段名2);限权规则code2(表名3.字段名3,表名4.字段名4)

例如：enterprise(channel.enterprise_code);account(table.column);channel(table3.id)

上下文传递工具类如下所示，使用回调的方式传递ThreadLocal可以防止使用者忘记清除上下文。

public class DataAuthContextUtil {
    /**
     * 不方便使用注解的地方，可以直接使用上下文设置数据规则
     */
    private static ThreadLocal<String> useDataAuth = new ThreadLocal<>();

    /**
     * 有的sql只在部分情况下需要使用数据权限限制

     * 上下文和注解中均可设置数据权限规则，都设置时，上下文中的优先
     *
     * @param supplier
     */
    public static <T> T executeSqlWithDataAuthRule(String rule, Supplier<T> supplier) {
        try {
            useDataAuth.set(rule);
            return supplier.get();
        } finally {
            useDataAuth.remove();
        }
    }

    /**
     * 获取数据权限标志
     *
     * @return
     */
    public static String getUseDataAuthRule() {
        return useDataAuth.get();
    }
}
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二、切片实现流程

三、其他技术细节

（1）在切面中获取原始sql

import lombok.extern.slf4j.Slf4j;
import org.apache.commons.collections4.CollectionUtils;
import org.apache.commons.lang3.StringUtils;
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.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.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;
import reactor.util.function.Tuple2;

import java.lang.reflect.Method;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
import java.util.Set;

@Component
@Intercepts({
//        @Signature(type = Executor.class, method = "update", args = {MappedStatement.class, Object.class}),
        @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})
})
@Slf4j
public class DataAuthInterceptor implements Interceptor {

    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        try {
            MappedStatement mappedStatement = (MappedStatement) invocation.getArgs()[0];
            BoundSql boundSql = mappedStatement.getBoundSql(invocation.getArgs()[1]);
            String sql = boundSql.getSql();
        } catch (Exception e) {
            log.error("数据权限添加出错,当前sql未加数据权限限制！", e);
            throw e;
        }
        return invocation.proceed();
    }
}
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（2）将权限项加入原始sql中

使用druid附带的ast解析功能修改sql，代码如下

/**
     * 权限限制写入sql
     *
     * @param sql
     * @param tableAuthMap key:table value1:column value2:values权限项
     * @return
     */
    public static StringBuilder addAuthLimitToSql(String sql, Map<String, Tuple2<String, Set<String>>> tableAuthMap) {
        List<SQLStatement> stmtList = SQLUtils.parseStatements(sql, "mysql");
        StringBuilder authSql = new StringBuilder();
        for (SQLStatement stmt : stmtList) {
            stmt.accept(new MySqlASTVisitorAdapter() {
                @Override
                public boolean visit(MySqlSelectQueryBlock x) {
                    SQLTableSource from = x.getFrom();
                    Set<String> tableList = new HashSet<>();
                    getTableList(from, tableList);
                    for (String tableName : tableList) {
                        if (tableAuthMap.containsKey(tableName)) {
                            x.addCondition(tableName + "in (...略)");
                        }
                    }
                    return true;
                }
            });
            authSql.append(stmt);
        }
        return authSql;
    }
    
    private static void getTableList(SQLTableSource from, Set<String> tableList) {
        if (from instanceof SQLExprTableSource) {
            SQLExprTableSource tableSource = (SQLExprTableSource) from;
            String name = tableSource.getTableName().replace("`", "");
            tableList.add(name);
            String alias = tableSource.getAlias();
            if (StringUtils.isNotBlank(alias)) {
                tableList.add(alias.replace("`", ""));
            }
        } else if (from instanceof SQLJoinTableSource) {
            SQLJoinTableSource joinTableSource = (SQLJoinTableSource) from;
            getTableList(joinTableSource.getLeft(), tableList);
            getTableList(joinTableSource.getRight(), tableList);
        } else if (from instanceof SQLSubqueryTableSource) {
            SQLSubqueryTableSource tableSource = (SQLSubqueryTableSource) from;
            tableList.add(tableSource.getAlias().replace("`", ""));
        } else if (from instanceof SQLLateralViewTableSource) {
            log.warn("SQLLateralView不用处理");
        } else if (from instanceof SQLUnionQueryTableSource) {
            //union 不需要处理
            log.warn("union不用处理");
        } else if (from instanceof SQLUnnestTableSource) {
            log.warn("Unnest不用处理");
        } else if (from instanceof SQLValuesTableSource) {
            log.warn("Values不用处理");
        } else if (from instanceof SQLWithSubqueryClause) {
            log.warn("子查询不用处理");
        } else if (from instanceof SQLTableSourceImpl) {
            log.warn("Impl不用处理");
        }
    }
}
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（3）将修改过后的sql写回mybatis

        MappedStatement ms = (MappedStatement) invocation.getArgs()[0];
        BoundSql boundSql = ms.getBoundSql(invocation.getArgs()[1]);
        // 组装 MappedStatement
        MappedStatement.Builder builder = new MappedStatement.Builder(ms.getConfiguration(), ms.getId(), new MySqlSource(boundSql), 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());
        MappedStatement newMappedStatement = builder.build();
        MetaObject metaObject = MetaObject.forObject(newMappedStatement, new DefaultObjectFactory(), new DefaultObjectWrapperFactory(), new DefaultReflectorFactory());
        metaObject.setValue("sqlSource.boundSql.sql", newSql);
        invocation.getArgs()[0] = newMappedStatement;
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参考文章： https://blog.csdn.net/e_anjing/article/details/79102693