mybatis返回List

Mybatis返回如List

private int design_id;  
private String idCreator ;    
private String picName; 
private String picUrl;  
private String showText;        
private Timestamp releaseTime;  
private Timestamp endTime  ; 

}

public class FormData {

        private int data_id ;   
        private String design_id ;    
        private String user_id ;    
        private  Timestamp  createTime;  
        private int isDelete ;   
        private String field1;   
        private String field2;    
        private String field3;
        private String field4;
        private String field5;

}

---

Controller 类

---

public class JoinController extends BaseController{
@Resource(name=”joinService”)
private JoinManager joinManager;
@ResponseBody
@RequestMapping( value=”getList.do” , produces= “application/json;charset=UTF-8”)
public Object getList( @RequestParam (value=”rd_session”) String rd_session ){

            String openId = null ;
            try {
                openId =    joinManager.getOpenIdByRd(rd_session);
            } catch (Exception e) {
                e.printStackTrace();
            }
            System.out.println(openId);

            List<Map>  designMap = null;
            try {
                designMap  =  joinManager.findDesignListByOpenid( openId  );
            } catch (Exception e) {      
                e.printStackTrace();
            }
            System.out.println( "designMap:"+designMap);
                JSONArray jsa = new JSONArray();
            JSONObject js = null;
             for (Map<String,Object> mp : designMap) {
                js = new JSONObject();
                  for (String k : mp.keySet()  ){
                      if ( k.equals("url")){
                        js.put(k,  Const.WEBSITE+mp.get(k));                     
                      }else{
                        js.put(k,  mp.get(k));              
                      }
                  }  
                  jsa.add(js);
                  System.out.println(jsa);
            }
            return jsa ;
  }
}

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JoinManager 接口
————————————
public interface JoinManager {

    // 通过rd_session获取  openid
public String getOpenIdByRd(String rd_session) throws Exception;


    //  获取参与的  表单的 design_id  List
public List<Map>  findDesignListByOpenid(String openId) throws Exception;

}
——————————————————————————————————————————————————————————————
JoinService 实现类
——————————

@Service(“joinService”)
public class JoinService implements JoinManager {

@Resource(name = "daoSupport")
    private DaoSupport dao;

/**
 * 获取openid
 */
@Override
public String getOpenIdByRd(  String rd_session) {
       return   dao.getOpenIdByRd(  "com.jy.entity.system.Join.findOpenId" ,rd_session) ;

}

@Override
public List<Map>  findDesignListByOpenid(String openId) throws Exception {
            return   (List<Map>) dao.findForList("com.jy.entity.system.Join.findDesignListByOpenid",  openId );
}

}
——————————————————————————————————————————————————————————————
JoinMapper.xml
——————————

     <select id="findDesignListByOpenid"   parameterType="String"   resultType="java.util.HashMap"   >  
        select   
            dt.data_id  as sid, dg.design_id  as sid , dg.title as title , dg.showText  as text, dg.picUrl as url 
        from
             form_data  dt     INNER JOIN   form_design   dg    on   dt.design_id  = dg.design_id
        where   
            dt.user_id  = #{openId}     
    </select>

PS:
1. 返回map时select列中最好设置别名。(经验证，当不设置别名时，你需要这个来取数据map.get(“count(*)”))。
select
count(*) as amount ,dt.data_id as sid, dg.design_id as sid , dg.title as title , dg.showText as text, dg.picUrl as url
from

1. 在mybatis中，无论你指定还是不指定返回类型，mybatis都会默认的先将查询回的值放入一个hashMap中（如果返回的值不止一条就是一个包含hashMap的list）。这其中的区别在于，如果你指定了返回类型，mybatis将会根据返回类型的实体类来从hashMap中获取值并set到这个实体类中。如果不指定就默认返回一个HashMap