在宁静的Web服务中使用没有主键的Hibernate从MySQL检索数据

Question

我正在使用restful web service开发Web应用程序。 我已经使用了hibernate和POJO进行mysql communication 。

我有具有用户表的数据库，主要数据库是empid 。 为了获得单行，我将empid从html页面传递到了Web服务，并将json对象返回到html页面（使用javascript进行解析）。

我已经使用这一行从数据库where empid=277;获得单行， where empid=277; //在这里硬编码

new_user =（用户）session.get（User.class，（long）277）;

我想从employeeid的其他列中检索记录（NOT empid，empid是主键）

select * user where employeeid="XX-123XD"

我已经从html页面（字符串）传递了employeeid 。

我写过像

    @POST
    @Path("/getjson")
    @Produces("application/json")
    public JSONObject sendjson(String employeeid) {

            Gson gsonobj = new Gson();
            JSONObject jsonobj = null;

            SessionFactory fact;
            fact = new Configuration().configure().buildSessionFactory();
            User new_user = null;

            Session session = fact.getCurrentSession();
            Transaction tx =  session.beginTransaction();
            Query query = session.createQuery("from user where employeeid= :employee");
            query.setParameter("employee", employeeid);
            //new_user = (User) session.get(User.class, (long)277);
            new_user = (User) query.list();

        try {    
            String jsonstr = gsonobj.toJson(new_user);
            jsonobj = new JSONObject(jsonstr);
        } catch (JSONException ex) {
            Logger.getLogger(Authneticate.class.getName()).log(Level.SEVERE, null, ex);
        }
        return jsonobj;
    }

但是我得到这样的错误，

type Exception report

message com.sun.jersey.api.client.ClientHandlerException: A message body reader for Java class org.codehaus.jettison.json.JSONObject, and Java type class org.codehaus.jettison.json.JSONObject, and MIME media type text/html; charset=utf-8 was not found

description The server encountered an internal error that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: com.sun.jersey.api.client.ClientHandlerException: A message body reader for Java class org.codehaus.jettison.json.JSONObject, and Java type class org.codehaus.jettison.json.JSONObject, and MIME media type text/html; charset=utf-8 was not found
    org.apache.jasper.servlet.JspServletWrapper.handleJspException(JspServletWrapper.java:549)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:470)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
root cause

com.sun.jersey.api.client.ClientHandlerException: A message body reader for Java class org.codehaus.jettison.json.JSONObject, and Java type class org.codehaus.jettison.json.JSONObject, and MIME media type text/html; charset=utf-8 was not found
    com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:561)
    com.sun.jersey.api.client.ClientResponse.getEntity(ClientResponse.java:517)
    org.apache.jsp.HomeUser_jsp._jspService(HomeUser_jsp.java:91)
    org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
    org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:432)
    org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:390)
    org.apache.jasper.servlet.JspServlet.service(JspServlet.java:334)
    javax.servlet.http.HttpServlet.service(HttpServlet.java:728)

如果我删除了Query语句，并取消注释代码，则该块为

    Session session = fact.getCurrentSession();
    Transaction tx =  session.beginTransaction();
    //Query query = session.createQuery("from user where employeeid= :employee");
    //query.setParameter("employee", employeeid);
    new_user = (User) session.get(User.class, (long)277);
    //new_user = (User) query.list();

然后它可以工作并给出empid=277的预期结果，这是主键。

我在做错查询。 还有休眠是否有其他方法可以在没有主键的情况下获取数据，例如

`new_user = (User) session.get(User.class, employeeid);`
                                                  |
                                          String(Not the primary key)

我的JSON对象的jsp文件是

<%

Client client = Client.create();
WebResource service = client.resource("http://localhost:8080/ITHelpdesk/webresources/hello/getjson");
String input = request.getParameter("username");
ClientResponse cliresponse = service.type("text/html").post(ClientResponse.class,input);
JSONObject jsonobj = cliresponse.getEntity(JSONObject.class);

%>

我试过使用new_user = (User) query.uniqueResult(); 然后也发生了相同的错误JSONObject jsonobj = cliresponse.getEntity(JSONObject.class);

谢谢

Answer 1

请使用查询方法uniqueResult（）。

 Query query = session.createQuery("from user where employeeid= :employee");
 query.setParameter("employee", employeeid);
 new_user = (User) query. uniqueResult();

Answer 2

您发布的客户端异常无济于事，可以提供服务器端异常stacktrace吗？ 我们必须知道什么冬眠的抱怨

Answer 3

解决，

代替

Query query = session.createQuery("from user where employeeid= :employee");
query.setParameter("employee", employeeid);

我已经添加了，

Query query = session.createQuery("from user where employeeid='" + employeeid + "'");

而且效果很好