Mybatis返回Map<code,name>

总结下Mybatis返回类型为Map<String,String>，且是Map<userCode,userName>这种类型的。

一、创建SessionMapper类，在UserServiceImpl中引入后，调用session.queryUserNameByUserCode()

@Service
public class SessionMapper extends SqlSessionDaoSupport {

   @Override
   @Resource
   public void setSqlSessionFactory(SqlSessionFactory sqlSessionFactory) {
      super.setSqlSessionFactory(sqlSessionFactory);
   }
/**
 * SQL中无传参，写RowBounds.DEFAULT,
 * 说明：UserMapper为Mapper的类名， queryUserNameByUserCode为mapper中的接口名（mapper.xml中的SQL的id）
 **/
 @SuppressWarnings("unchecked")
 public Map<String,String> queryUserNameByUserCode() {
    MapResultHandler handler = new MapResultHandler();
    this.getSqlSession().select(UserMapper.class.getName()+ ".queryUserNameByUserCode", RowBounds.DEFAULT, handler);
    Map<String, String> map = handler.getMappedResults();
    return map;
}
 /**
  * SQL中有传参
  **/

 @SuppressWarnings("unchecked")
 public Map<String,String> queryUserNameByUserCode2(List userCodeList) {
    MapResultHandler handler = new MapResultHandler();
    this.getSqlSession().select(UserMapper.class.getName()+ ".queryUserNameByUserCode2", userCodeList, handler);
    Map<String, String> map = handler.getMappedResults();
    return map;
}

}

 二、创建MapResultHandler

import org.apache.ibatis.session.ResultContext;
import org.apache.ibatis.session.ResultHandler;

public class MapResultHandler 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();
          //xml配置里面的property的值，对应的列
          mappedResults.put(map.get("key"), map.get("value"));

    }
     
    public Map getMappedResults() {
       return mappedResults;
       
    }
}

三、UserMapper.class

Map<String, String> queryUserInfo();

四、UserMapper.xml加上：

<resultMap id = "codeNameMap" type = "java.util.HashMap" >
   <result property="key" column = "userCode"/>
   <result property="value" column = "userName"/>
</resultMap>
  

SQL语句：

<select id= "queryUserInfo" resultMap="codeNameMap">
  select user_code,user_name from user
</select>

这样返回的Map就是以code为key，以name为value的形式了。