hibernate的报错信息a different object with the same identifier value was already associated with the session解决办法

废话不多说,直接说原因,这是在hibernate中,有2个相同类型的实体类具有同样的主键标识符,然后调用update或者调用saveorupdate,我朋友出这个错的由于他想要update一条数据时,获取主键时从数据库查询获取,此时接收的对象的主键id是12,吧这个值赋给要更新入参的对象,2个对象的主键就都是12了,所有会报错,

 1 @override
 2     public dto createexaminfo(dto dto) {
 3 
 4         integer examid = getparamutil.convertobject(dto.getparam("examid"));
 5         examinfo examinfo=new examinfo();
 6         examinfo examinfo = examinfolist.get(0);
 7         
 8         examinfo.setexamid(examid);
 9         integer exampaperid = getparamutil.convertobject(dto.getparam("exampaperid"));
10         examinfo.setexampaperid(exampaperid);
11         string title = getparamutil.converobject(dto.getparam("title"));
12         examinfo.settitle(title);
13         integer pattern = getparamutil.convertobject(dto.getparam("pattern"));
14         examinfo.setpattern(pattern);
15         integer type = getparamutil.convertobject(dto.getparam("type"));
16         examinfo.settype(type);
17         integer form = getparamutil.convertobject(dto.getparam("form"));
18         examinfo.setform(form);
19         integer monitor = getparamutil.convertobject(dto.getparam("monitor"));
20         examinfo.setmonitor(monitor);
21         string isperpetual = getparamutil.converobject(dto.getparam("isperpetual"));
22         examinfo.setisperpetual(isperpetual);
23         string starttime = getparamutil.converobject(dto.getparam("starttime"));
24         examinfo.setstarttime(starttime);
25         string endtime = getparamutil.converobject(dto.getparam("endtime"));
26         examinfo.setendtime(endtime);
27         string examcreatetime = getparamutil.converobject(dto.getparam("examcreatetime"));
28         examinfo.setexamcreatetime(examcreatetime);
29         string createdate = getparamutil.converobject(dto.getparam("createdate"));
30         examinfo.setcreatedate(createdate);
31         examinfo.setisused(0);
32         examinfo.setdelflg("0");
33         list<examinfo> examinfolist=examinfodao.findbyproperty("examid", examid);
34         if (examinfolist!=null&&examinfolist.size()>0) {
35             examinfo.setid(examinfolist.get(0).getid());
36             examinfodao.update(examinfo);
37         }else{
38             examinfodao.save(examinfo);
39         }
40         
41         return null;
42     }

第33行查出了这条数据,此时会话中包含一个id是12的对象(就是此时想要更新的那条数据的主键),然后35行又把id赋值给了另一个对象,执行update时就会报错,我给他改进了一下代码,如下:

 1 @override
 2     public dto createexaminfo(dto dto) {
 3 
 4         integer examid = getparamutil.convertobject(dto.getparam("examid"));
 5         list<examinfo> examinfolist=examinfodao.findbyproperty("examid", examid);
 6 //        examinfo examinfo=new examinfo();
 7         examinfo examinfo = examinfolist.get(0);
 8         
 9         examinfo.setexamid(examid);
10         integer exampaperid = getparamutil.convertobject(dto.getparam("exampaperid"));
11         examinfo.setexampaperid(exampaperid);
12         string title = getparamutil.converobject(dto.getparam("title"));
13         examinfo.settitle(title);
14         integer pattern = getparamutil.convertobject(dto.getparam("pattern"));
15         examinfo.setpattern(pattern);
16         integer type = getparamutil.convertobject(dto.getparam("type"));
17         examinfo.settype(type);
18         integer form = getparamutil.convertobject(dto.getparam("form"));
19         examinfo.setform(form);
20         integer monitor = getparamutil.convertobject(dto.getparam("monitor"));
21         examinfo.setmonitor(monitor);
22         string isperpetual = getparamutil.converobject(dto.getparam("isperpetual"));
23         examinfo.setisperpetual(isperpetual);
24         string starttime = getparamutil.converobject(dto.getparam("starttime"));
25         examinfo.setstarttime(starttime);
26         string endtime = getparamutil.converobject(dto.getparam("endtime"));
27         examinfo.setendtime(endtime);
28         string examcreatetime = getparamutil.converobject(dto.getparam("examcreatetime"));
29         examinfo.setexamcreatetime(examcreatetime);
30         string createdate = getparamutil.converobject(dto.getparam("createdate"));
31         examinfo.setcreatedate(createdate);
32         examinfo.setisused(0);
33         examinfo.setdelflg("0");
34         if (examinfolist!=null&&examinfolist.size()>0) {
35 //            examinfo.setid(examinfolist.get(0).getid());
36             examinfodao.update(examinfo);
37         }else{
38             examinfodao.save(examinfo);
39         }
40         
41         return null;
42     }

直接采用查出数据时接收的对象作为更新时的入参,在这期间给对象set参数,这样从始至终主键为12的对象就只有一个了