mybatis自定义插件动态修改sql语句

step1:定义Interceptor实现org.apache.ibatis.plugin.Interceptor

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
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.mapping.SqlSource;
import org.apache.ibatis.plugin.*;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.RowBounds;
import org.springframework.beans.factory.annotation.Value;

import java.util.Properties;

/**
 * code by me
 * <p>
 * Data:2017/8/10 Time:11:28
 * User:lbh
 */
@Intercepts
        ({
                @Signature(type = Executor.class, method = "query", args = {MappedStatement.class, Object.class, RowBounds.class, ResultHandler.class}),
        })
public class FDNSqlInterceptor implements Interceptor {
    private static Log logger = LogFactory.getLog(FDNSqlInterceptor.class);

    @Value("${fdn.open}")
    private boolean fdnOpen;

    static int MAPPED_STATEMENT_INDEX = 0;// 这是对应上面的args的序号
    static int PARAMETER_INDEX = 1;
    static int ROWBOUNDS_INDEX = 2;
    static int RESULT_HANDLER_INDEX = 3;
    @Override
    public Object intercept(Invocation invocation) throws Throwable {
        if(!fdnOpen){
            return invocation.proceed();
        }
        final Object[] queryArgs = invocation.getArgs();
        final MappedStatement mappedStatement = (MappedStatement) queryArgs[MAPPED_STATEMENT_INDEX];
        final Object parameter = queryArgs[PARAMETER_INDEX];
        final BoundSql boundSql = mappedStatement.getBoundSql(parameter);

        String sql = boundSql.getSql();
        if(sql.contains("xx_pro")){
            sql = sql.replace("xx_pro","xx_pro_fdn");
        }

        // 重新new一个查询语句对像
        BoundSql newBoundSql = new BoundSql(mappedStatement.getConfiguration(), sql, boundSql.getParameterMappings(), boundSql.getParameterObject());
        // 把新的查询放到statement里
        MappedStatement newMs = copyFromMappedStatement(mappedStatement, new BoundSqlSqlSource(newBoundSql));
        for (ParameterMapping mapping : boundSql.getParameterMappings()) {
            String prop = mapping.getProperty();
            if (boundSql.hasAdditionalParameter(prop)) {
                newBoundSql.setAdditionalParameter(prop, boundSql.getAdditionalParameter(prop));
            }
        }
        queryArgs[MAPPED_STATEMENT_INDEX] = newMs;
        return invocation.proceed();
    }

    @Override
    public Object plugin(Object target) {
        return Plugin.wrap(target, this);
    }

    @Override
    public void setProperties(Properties properties) {

    }

    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());
        if (ms.getKeyProperties() != null && ms.getKeyProperties().length > 0) {
            builder.keyProperty(ms.getKeyProperties()[0]);
        }
        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();
    }

    public static class BoundSqlSqlSource implements SqlSource {
        private BoundSql boundSql;
        public BoundSqlSqlSource(BoundSql boundSql) {
            this.boundSql = boundSql;
        }
        public BoundSql getBoundSql(Object parameterObject) {
            return boundSql;
        }
    }
}

step2:在mybatis的配置文件中加入plugin

　　<plugins>
        <plugin interceptor="xx.interceptor.FDNSqlInterceptor"></plugin>
    </plugins>