Question

我尝试使用MySql和Hibernate创建简单的JPA应用程序，我想从表学生中加载4条记录 db table

但是我收到了这个错误：

Exception in thread "main" javax.ejb.EJBTransactionRolledbackException: Named query not found: findAll

这是我的实体类

package entity;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.NamedQueries;
import javax.persistence.NamedQuery;
import javax.persistence.Table;

@Entity
@Table(name="student")
@NamedQueries({
    @NamedQuery(name = "findAll", query = "select st from student st")
    })
public class student{

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int id;

    @Column(name="name")
    private String name;

    @Column(name="surname")
    private String surname;

    @Column(name="sex")
    private String sex;

    public student(String name, String surname, String sex) {
        this.name = name;
        this.surname = surname;
        this.sex = sex;
    }

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public String getSurname() {
        return surname;
    }

    public void setSurname(String surname) {
        this.surname = surname;
    }

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    @Override
    public String toString() {
        return "student [id=" + id + ", name=" + name + ", surname=" + surname + ", sex=" + sex + "]";

}

DAO

package dao;

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.Query;
import javax.persistence.TypedQuery;

import entity.student;

public class StudentDAO {

    public List<student> getAllStd(EntityManager em){
        TypedQuery<student> q = em.createNamedQuery("findAll", student.class);
        return q.getResultList();       
    }       
}

最后调用DAO方法的bean

package test;

import java.util.List;

import javax.ejb.Stateless;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.TypedQuery;

import dao.StudentDAO;
import entity.student;

@Stateless
public class Test2Bean {

    @PersistenceContext()
    private EntityManager em;       

     public void getAllStudents(){
         StudentDAO stdDAO = new StudentDAO();
         List<student> students = stdDAO.getAllStd(em);
         System.out.println(students.size());
     }      
}

的persistence.xml

<?xml version="1.0" encoding="UTF-8"?>
<persistence version="2.0"
 xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xsi:schemaLocation="
 http://java.sun.com/xml/ns/persistence
 http://java.sun.com/xml/ns/persistence/persistence_2_0.xsd">
 <persistence-unit name="mysql">
 <provider>org.hibernate.ejb.HibernatePersistence</provider>
 <jta-data-source>java:jboss/mysqlds</jta-data-source>
 <exclude-unlisted-classes>false</exclude-unlisted-classes>
 <properties>

 <property name="hibernate.show_sql" value="true" />
 <property name="hibernate.hbm2ddl.auto" value="update" />
 <property name="hibernate.use_sql_comments" value="true" />
 <property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
</properties>

</persistence-unit>

</persistence>

我不知道为什么DAO方法无法访问查询，我在实体类中做了很少的测试方法，DAO方法可以访问实体学生。

我添加了完整的错误消息http://pastebin.com/agBxHg7K

感谢所有答案

Answer 1

...试

@Entity
@Table(name="student")
@NamedQueries({
@NamedQuery(name = "Student.findAll", query = "select st from student st")
})
public class student{

添加学生。在“findAll”之前

不确定是不是这样，但我的命名查询通常都有。

javax.ejb.EJBTransactionRolledbackException：找不到命名查询：findAll

1 个答案: