Mybatis select返回值为map时,选取表字段的两列作为key,value

最近需要用到Mybatis中查询结果集为Map的功能,查了好多资料,最终搞定。其实只需要重写ResultHandler接口,,然后用SqlSession 的select方法,将xml里面的映射文件的返回值配置成 HashMap 就可以了。具体过程如下

1、先看看xml文件怎么配置

<resultMap id="getAllSetDaysResult"   type="HashMap">
    <result property="key" column="SP_FPARAMEKEY" />
    <result property="value" column="SP_FPARAMEVALUE" />
</resultMap>

2、sql

<select id="getAllSetDays" resultMap="getAllSetDaysResult">
SELECT SP.FPARAMEKEY SP_FPARAMEKEY, SP.FPARAMEVALUE SP_FPARAMEVALUE
  FROM T_SERVER_PARAMETER SP
 WHERE SP.FPARAMEKEY IN ('XXX')
</select> 

3、重写org.apache.ibatis.session 中ResultHandler接口:

public class FblMapResultHandler implements ResultHandler {
    @SuppressWarnings("rawtypes")
    private final Map mappedResults = new HashMap();
 
    @SuppressWarnings("unchecked")
    @Override
    public void handleResult(ResultContext context) {
        @SuppressWarnings("rawtypes")
        Map map = (Map) context.getResultObject();
        mappedResults.put(map.get("key"), map.get("value"));  // xml 配置里面的property的值,对应的列
    }
    public Map getMappedResults() { 
        return mappedResults; 
    } 
}
 

4、调用select方法:

FblMapResultHandler fbl = new FblMapResultHandler();
getSqlSession().select(NAMESPACE +"getAllSetDays",fbl);
@SuppressWarnings("rawtypes")
Map map =fbl.getMappedResults();
return map;