Mybatis拦截器如何实现数据权限过滤

package org.apache.ibatis.plugin;  
  
import java.util.Properties;  
  
public interface Interceptor {  
	
    Object intercept(Invocation invocation) throws Throwable;  

    default Object plugin(Object target) {  
        return Plugin.wrap(target, this);  
    }  
    
    default void setProperties(Properties properties) {  
    }  
}

@Documented  
@Retention(RetentionPolicy.RUNTIME)  
@Target({})  
public @interface Signature {  
	Class<?> type();

	String method();

	Class<?>[] args();
}

public class DataAccessMethod {  
    private static final ThreadLocal<DataAccessType[]> ACCESS_LOCAL = new ThreadLocal<>();  
  
  
    public DataAccessMethod() {  
  
    }  
    public static void setLocalAccess(DataAccessType... accessType) {  
        ACCESS_LOCAL.set(accessType);  
    }  
  
    public static DataAccessType[] getLocalAccess() {  
        return ACCESS_LOCAL.get();  
    }  
  
    public static void clearLocalAccess() {  
        ACCESS_LOCAL.remove();  
    }  
  
    public static void accessData(DataAccessType... accessType) {  
        setLocalAccess(accessType);  
    }  
}

@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}  
)})  
@Slf4j  
@Component  
public class DataAccessFilterInterceptor implements Interceptor {  
  
  
    @Override  
    public Object intercept(Invocation invocation) throws Throwable {  
        if (skip()) {  
            return invocation.proceed();  
        }  
        MappedStatement statement = (MappedStatement) invocation.getArgs()[0];  
        Object parameter = invocation.getArgs()[1];  
        BoundSql boundSql = statement.getBoundSql(parameter);  
        String originalSql = boundSql.getSql();  
        Object parameterObject = boundSql.getParameterObject();  
        String sql = addTenantCondition(originalSql, "1", "222");  
        log.info("原SQL：{}， 数据权限替换后的SQL：{}", originalSql, sql);  
  
        BoundSql newBoundSql = new BoundSql(statement.getConfiguration(), sql, boundSql.getParameterMappings(), parameterObject);  
        MappedStatement newStatement = copyFromMappedStatement(statement, new BoundSqlSqlSource(newBoundSql));  
        invocation.getArgs()[0] = newStatement;  
        return invocation.proceed();  
    }  
  
    /**  
     * 判断是否跳过  
     *  
     * @return 是否跳过  
     */  
    private boolean skip() {  
        DataAccessType[] localAccess = DataAccessMethod.getLocalAccess();  
        return localAccess == null;  
    }  
  
    private String addTenantCondition(String originalSql, String depId, String alias) {  
        String field = "id";  
        if (StringUtils.hasText(alias)) {  
            field = alias + "." + field;  
        }  
  
        StringBuilder sb = new StringBuilder(originalSql.toLowerCase());  
        int index = sb.indexOf("where");  
        sb = new StringBuilder(originalSql);  
        if (index < 0) {  
            sb.append(" where ").append(field).append(" = ").append(depId);  
        } else {  
            sb.insert(index + 5, " " + field + " = " + depId + " and ");  
        }  
        return sb.toString();  
    }  
  
    private MappedStatement copyFromMappedStatement(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());  
        builder.timeout(ms.getTimeout());  
        builder.parameterMap(ms.getParameterMap());  
        builder.resultMaps(ms.getResultMaps());  
        builder.cache(ms.getCache());  
        builder.useCache(ms.isUseCache());  
        return builder.build();  
    }  
  
    public static class BoundSqlSqlSource implements SqlSource {  
        private final BoundSql boundSql;  
  
        public BoundSqlSqlSource(BoundSql boundSql) {  
            this.boundSql = boundSql;  
        }  
  
        @Override  
        public BoundSql getBoundSql(Object parameterObject) {  
            return boundSql;  
        }  
    }  
  
  
}