IllegalArgumentException：为TypedQuery [model.User]指定的类型与查询返回类型[class model.User]不兼容

问题描述

我在创建泛型类型的TypedQuery时遇到了这个间歇性错误。我的方法如下：

  public List< T> findByEmail（Class type，String email_id）{
 String query =SELECT t FROM+ type.getSimpleName（）+t WHERE t.email =：+ email_id; 
 TypedQuery< T> typedQuery = em.createQuery（query，type）; 
 return（List< T>）typedQuery.getResultList（）; 
} 
  

如果我重新启动服务器，错误不会再出现，取结果。

  play.api.Application $$ anon $ 1：执行异常[[IllegalArgumentException：为TypedQuery [model.User]指定的类型是与查询返回类型不兼容[class model.User]]] 
 at play.api.Application $ class.handleError（Application.scala：296）〜[play_2.11-2.3.7.jar：2.3.7] 
 at play.api.DefaultApplication.handleError（Application.scala：402）[play_2.11-2.3.7.jar：2.3.7] 
 at play.core.server.netty.PlayDefaultUpstreamHandler $$ anonfun $ 3 $$ anonfun 
 $ applyOrElse $ 4.apply（PlayDefaultUpstreamHandler.scala：320）[play_2.11-2.3.7.jar：
 2.3.7] 
 at play.core.server .netty.PlayDefaultUpstreamHandler $$ anonfun $ 3 $$ anonfun 
 $ applyOrElse $ 4.apply（PlayDefaultUpstreamHandler.scala：320）[play_2.11-2.3.7.jar：2.3.7] 
 at scala.Option .map（Option.scala：145）[scala-library-2.11.1.jar：na] 
引起：java.lang.IllegalArgumentException：为TypedQuery [model.User]指定的类型是i与org.hibernate.jpa.spi.AbstractEntityManagerImpl.resultClassChecking（AbstractEntityManagerImpl.java:387）〜[hibernate-entitymanager-4.3.6.Final.jar：4.3。 6.Final] 
 at org.hibernate.jpa.spi.AbstractEntityManagerImpl.createQuery（AbstractE 
 ntityManagerImpl.java:344）〜[hibernate-entitymanager-4.3.6.Final.jar：4.3.6。最终
] 
 at sun.reflect.NativeMethodAccessorImpl.invoke0（Native Method）〜[na：1.8。 
 0_25] 
 at sun.reflect.NativeMethodAccessorImpl.invoke（NativeMethodAccessorImpl。
 java：62）〜[na：1.8.0_25] 
 at sun.reflect.DelegatingMethodAccessorImpl.invoke（ DelegatingMethodAcces 
 sorImpl.java:43）〜[na：1.8.0_25] 
  

解决方案

问题是

  TypedQuery< T> typedQuery = em.createQuery（query.toString（），type）; 
  

这里var type是一个Class对象而不是User类，你需要这样做。 / p>

  TypedQuery< T> typedQuery = em.createQuery（query.toString（），Class.forName（type.getSimpleName（）））; 
  

这将返回一个Class并且TypedQuery将在运行时变为TypedQuery

I am getting this intermittent error while creating a TypedQuery for Generic type. My method is as:

    public List<T> findByEmail(Class type, String email_id){
        String query = "SELECT t FROM " + type.getSimpleName() + " t WHERE t.email =:"+email_id;
        TypedQuery<T> typedQuery =em.createQuery(query, type);
        return (List<T>) typedQuery.getResultList();
   }

While if I restart the server, the error doesn't reappear and it correctly fetch result.

play.api.Application$$anon$1: Execution exception[[IllegalArgumentException: Type specified for TypedQuery [model.User] is incompatible with query return type [class model.User]]]
            at play.api.Application$class.handleError(Application.scala:296) ~[play_2.11-2.3.7.jar:2.3.7]
            at play.api.DefaultApplication.handleError(Application.scala:402) [play_2.11-2.3.7.jar:2.3.7]
            at play.core.server.netty.PlayDefaultUpstreamHandler$$anonfun$3$$anonfun
    $applyOrElse$4.apply(PlayDefaultUpstreamHandler.scala:320) [play_2.11-2.3.7.jar:
    2.3.7]
            at play.core.server.netty.PlayDefaultUpstreamHandler$$anonfun$3$$anonfun
    $applyOrElse$4.apply(PlayDefaultUpstreamHandler.scala:320) [play_2.11-2.3.7.jar:2.3.7]
            at scala.Option.map(Option.scala:145) [scala-library-2.11.1.jar:na]
    Caused by: java.lang.IllegalArgumentException: Type specified for TypedQuery [model.User] is incompatible with query return type [class model.User]
            at org.hibernate.jpa.spi.AbstractEntityManagerImpl.resultClassChecking(AbstractEntityManagerImpl.java:387) ~[hibernate-entitymanager-4.3.6.Final.jar:4.3.6.Final]
            at org.hibernate.jpa.spi.AbstractEntityManagerImpl.createQuery(AbstractE
    ntityManagerImpl.java:344) ~[hibernate-entitymanager-4.3.6.Final.jar:4.3.6.Final
    ]
            at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:1.8.
    0_25]
            at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
    java:62) ~[na:1.8.0_25]
            at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
    sorImpl.java:43) ~[na:1.8.0_25]

解决方案

The problem is

TypedQuery<T> typedQuery =em.createQuery(query.toString(), type);

Here var type is a Class Object not the User class, you need to do something like this.

TypedQuery<T> typedQuery =em.createQuery(query.toString(), Class.forName(type.getSimpleName()));

this will return a Class and TypedQuery will become TypedQuery in runtime

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