自定义Mybatis返回类型及注意事项

一、自定义返回拦截器
package com.yaoex.crm.service.util;

import org.apache.ibatis.session.ResultContext;
import org.apache.ibatis.session.ResultHandler;
import org.apache.ibatis.session.SqlSessionFactory;
import org.mybatis.spring.SqlSessionTemplate;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Component;

import java.util.HashMap;
import java.util.Map;

/**
 * @Title: MapResultHandler
 * @Package: com.yaoex.crm.service.util
 * @description:
 **/

@Component
public class MapResultHandler implements ResultHandler {
    private static final Logger log = LoggerFactory.getLogger(MapResultHandler.class);

    private static SqlSessionTemplate sqlSessionTemplate;

    @Autowired
    public void setSqlSessionTemplate(SqlSessionFactory sqlSessionFactory) {
        MapResultHandler.sqlSessionTemplate = new SqlSessionTemplate(sqlSessionFactory);
    }

    @SuppressWarnings("rawtypes")
    private final Map mappedResults = new HashMap();

    @SuppressWarnings("unchecked")
    @Override
    public void handleResult(ResultContext context) {
        @SuppressWarnings("rawtypes")
        Map map = (Map) context.getResultObject();
        if(map.get("key") != null && map.get("value") != null ){
            // xml配置里面的property的值，对应的列
            mappedResults.put(map.get("key"), map.get("value"));
        }
    }

    @SuppressWarnings("rawtypes")
    public Map getMappedResults() {
        return mappedResults;
    }

    public static Map getMapResults(String statementId,Map<String,Object> param){
        MapResultHandler handler = new MapResultHandler();
        sqlSessionTemplate.select(statementId,param,handler);
        return handler.getMappedResults();
    }
}

二、mybatis配置

<resultMap id="levelCountMap" type="java.util.Map" >
  <result column="cust_level" property="key" jdbcType="INTEGER" />
  <result column="count" property="value" jdbcType="INTEGER" />
</resultMap>

<select id="selectCountByLevel" resultMap="levelCountMap">
  SELECT l.cust_level,COUNT(l.cust_level) as count from t_crm_customer_level l
  GROUP BY l.cust_level
</select>

三、调用方式

Map<Integer,Long> results = MapResultHandler.getMapResults("com.yaoex.crm.dao.customerdata.CrmCustomerLevelDao.selectCountByLevel", null);