hibernate的常见错误

出现 org.hibernate.HibernateException:No CurrentSessionContext configured! 这个错误

一般这个报错都是hibernate.cfg.xml的配置出现了问题

例如：

<property name="hibernate_current_session_context_class">thread</property>

看似没有错误

正确的写法：

<property name="hibernate.current_session_context_class">thread</property>

有些人非常容易忽视这个错误，比如我！！

这个hibernate 其他的核心写法

×　Ｕsers映射代码

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- Generated 2016-11-26 15:34:57 by Hibernate Tools 3.4.0.CR1 -->
<hibernate-mapping>
    <class name="entity.Users" table="USERS">

    <id name="uid" type="int">
        <generator class="native" />
    </id>

    <property name="username" type="java.lang.String" />
    <property name="password" type="java.lang.String" />
    </class>

</hibernate-mapping>

实体类代码

package entity;
public class Users {
     private int uid;
     private String username;
     private String password;

    public Users(int uid, String username, String password) {
        super();
        this.uid = uid;
        this.username = username;
        this.password = password;
    }
    public Users() {
        super();
        // TODO Auto-generated constructor stub
    }
    public int getUid() {
        return uid;
    }
    public void setUid(int uid) {
        this.uid = uid;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }

}

hibernate.cfg.xml的配置

<!DOCTYPE hibernate-configuration PUBLIC
    "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
    "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
    <session-factory>
        <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property>
        <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/test</property>
        <property name="hibernate.connection.username">root</property>
        <property name="hibernate.connection.password">123456</property>
        <!-- hibernate配置数据库方言 -->
        <property name="hibernate.dialect">org.hibernate.dialect.MySQLDialect</property>
        <!-- 2. 其他相关配置 -->
        <!-- 2.1 显示hibernate在运行时候执行的sql语句 -->
        <property name="show_sql">true</property>
        <!-- 2.2 格式化sql -->
        <property name="format_sql">true</property>
        <!-- 2.3 自动建表 -->
        <property name="hbm2ddl.auto">update</property>
        <property name="hibernate.current_session_context_class">thread</property>

        <mapping resource="entity/Students.hbm.xml" />
        <mapping resource="entity/Users.hbm.xml" />
    </session-factory>
</hibernate-configuration>

测试Ｕsers和Studenss映射到数据库的代码
package test;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.tool.hbm2ddl.SchemaExport;
import org.junit.Test;

    public class TestStudents{
    @Test
        public void TestSchemaExport(){

        //创建配置对象
            Configuration config=new Configuration().configure();
        //创建服务对象
            //ServiceRegistry serviceRegistry= new ServiceRegistryBuilder().applySettings(config.getProperties()).buildServiceRegistry();
        //创建session Factory
            SessionFactory sessionFactory=config.buildSessionFactory();
        //创建session对象
//            Session session =sessionFactory.openSession();
        //shemaExport要重构Hibernate-core使用hibernate4以下的版本，5的不行
            SchemaExport export=new SchemaExport(config);
        export.create(true,true);
        }
}

单例模式设置

package db;
import org.hibernate.SessionFactory;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.service.ServiceRegistryBuilder;
public class MyHibernateSessionFaction {
    private  static SessionFactory sessionFactory; //会话工厂属性
    //构造方法私有化。保证单例模式
    private MyHibernateSessionFaction(){

    }

    //公有的静态方法，获得会话工厂对象
    public static SessionFactory getSessionFactory(){
        if(sessionFactory==null){
            Configuration config=new Configuration().configure();

            ServiceRegistry serviceRegistry=new ServiceRegistryBuilder().applySettings(config.getProperties()).build();
            sessionFactory=config.buildSessionFactory(serviceRegistry);
            return sessionFactory;
        }else{
            return sessionFactory;
        }
    }

}

登录的实现方法

package service.impl;

import java.util.List;


import org.hibernate.Query;
import org.hibernate.Session;
import org.hibernate.Transaction;

import service.UsersDAO;
import db.MyHibernateSessionFaction;
import entity.Users;

public class UsersDAOImpl implements UsersDAO{

    @Override
    public boolean usersLogiin(Users u) {
        // TODO Auto-generated method stub
        Transaction tx=null;
        String hql="";
        try{
            Session session=MyHibernateSessionFaction.getSessionFactory().getCurrentSession();
            tx=session.beginTransaction();
            hql= "from Users where username=? and password=? ";
            Query query=session.createQuery(hql);
            query.setParameter(0, u.getUsername());
            query.setParameter(1, u.getPassword());
            List list=query.list();
            tx.commit();
            if(list.size()>0){
                return true;
            }else{
                return false;
            }
        }
        catch(Exception ex){
            ex.printStackTrace();
            return false;
        }
        finally{
            if(tx!=null){

                    //tx.commit();
                    tx=null;
            }
        }
    }

}

*　测试代码

package service.impl;


import junit.framework.Assert;

import org.junit.Test;

import service.UsersDAO;
import entity.Users;

public class TestUserDAOImpl {

    @Test
    public void testUserLogin(){

        Users u=new Users(1,"zhangsan","123456");
        UsersDAO udao=new UsersDAOImpl();
        Assert.assertEquals(true, udao.usersLogiin(u));

    }
}