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Mybatis攔截器如何實(shí)現(xiàn)數(shù)據(jù)權(quán)限過(guò)濾

更新時(shí)間：2024年12月31日 14:14:29 作者：CodeLemon·

本文介紹了MyBatis攔截器的使用,通過(guò)實(shí)現(xiàn)Interceptor接口對(duì)SQL進(jìn)行處理,實(shí)現(xiàn)數(shù)據(jù)權(quán)限過(guò)濾功能,通過(guò)在本地線程變量中存儲(chǔ)數(shù)據(jù)權(quán)限相關(guān)信息,并在攔截器的intercept方法中進(jìn)行SQL增強(qiáng)處理

背景

現(xiàn)在的項(xiàng)目負(fù)責(zé)人去年年底離職，導(dǎo)致前期規(guī)劃的數(shù)據(jù)過(guò)濾功能一直沒(méi)有去實(shí)現(xiàn)。

現(xiàn)在項(xiàng)目馬上進(jìn)入試運(yùn)行時(shí)期了，需要根據(jù)用戶數(shù)據(jù)權(quán)限的配置對(duì)數(shù)據(jù)進(jìn)行過(guò)濾處理。

如果一個(gè)個(gè)手動(dòng)去Mapper.xml文件中修改SQL工作量太大了，后面我考慮通過(guò)Mybatis對(duì)查詢的SQL進(jìn)行處理。

基礎(chǔ)知識(shí)

Mybatis 攔截器介紹

Interceptor接口源碼解析

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) {  
    }  
}

intercept 方法
這個(gè)方法是核心，當(dāng)攔截到調(diào)用時(shí)會(huì)執(zhí)行。Invocation 對(duì)象包含了被攔截方法的所有信息，包括方法本身、參數(shù)、目標(biāo)對(duì)象等。在這個(gè)方法中，你可以做任何預(yù)處理或后處理邏輯，然后通過(guò)調(diào)用 invocation.proceed() 來(lái)繼續(xù)執(zhí)行原方法，或者直接返回自定義的結(jié)果。
plugin方法
這個(gè)方法用于決定是否對(duì)某個(gè)對(duì)象應(yīng)用攔截器。如果返回 target，則表示不進(jìn)行攔截；如果返回一個(gè)新的對(duì)象，則表示將使用這個(gè)新對(duì)象替代原有的對(duì)象，通常是在這里返回一個(gè)代理對(duì)象。
setProperties 方法
用于設(shè)置攔截器的屬性，這些屬性可以在 MyBatis 的配置文件中定義。

Signature 注解源碼解析

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

	String method();

	Class<?>[] args();
}

type：表示目標(biāo)對(duì)象的類型，
method：表示要攔截的目標(biāo)方法的名字。
args：表示目標(biāo)方法的參數(shù)類型列表。不同的 @Signature 注解可能有不同的參數(shù)類型列表，這取決于具體的方法簽名。

代碼實(shí)戰(zhàn)

實(shí)現(xiàn)一個(gè)類似與PageHelper的一個(gè)工具類，在本地線程變量中存儲(chǔ)數(shù)據(jù)權(quán)限相關(guān)信息

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);  
    }  
}

實(shí)現(xiàn) Interceptor接口對(duì)SQL進(jìn)行增強(qiáng)處理

@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：{}， 數(shù)據(jù)權(quán)限替換后的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();  
    }  
  
    /**  
     * 判斷是否跳過(guò)  
     *  
     * @return 是否跳過(guò)  
     */  
    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;  
        }  
    }  
  
  
}