Hibernate的注解和检索

Posted 2020-10-12

Hibernate是一个开放源代码的对象关系映射框架，它对JDBC进行了非常轻量级的对象封装，它将POJO与数据库表建立映射关系，是一个全自动的orm框架，hibernate可以自动生成SQL语句，自动执行，使得Java程序员可以随心所欲的使用对象编程思维来操纵数据库。 Hibernate可以应用在任何使用JDBC的场合，既可以在Java的客户端程序使用，也可以在Servlet/JSP的Web应用中使用，最具革命意义的是，Hibernate可以在应用EJB的J2EE架构中取代CMP，完成数据持久化的重任。

注解：新闻表和评论表

comment.java

package com.cn.pojo;

import java.io.Serializable;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
import javax.persistence.Table;
@Entity
@Table(name="t_comment")
public class Comment implements Serializable{
    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer id;
    private String commentContent;
    @ManyToOne(cascade=CascadeType.ALL,fetch=FetchType.LAZY,targetEntity=News.class)
    @JoinColumn(name="news_id",nullable=false)
    private News news;
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getCommentContent() {
        return commentContent;
    }
    public void setCommentContent(String commentContent) {
        this.commentContent = commentContent;
    }
    public News getNews() {
        return news;
    }
    public void setNews(News news) {
        this.news = news;
    }
    public Comment() {
        super();
    }
    public Comment(String commentContent) {
        super();
        this.commentContent = commentContent;
    }
    
    
}

News.java

package com.cn.pojo;

import java.io.Serializable;
import java.util.HashSet;
import java.util.Set;

import javax.persistence.CascadeType;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.OneToMany;
import javax.persistence.Table;

@Entity
@Table(name="t_news")
public class News implements Serializable{

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Integer id;
    private String title;
    private String content;
    @OneToMany(cascade=CascadeType.ALL,fetch=FetchType.LAZY,targetEntity=Comment.class,mappedBy="news")
    private Set<Comment> comments=new HashSet<Comment>();
    public Integer getId() {
        return id;
    }
    public void setId(Integer id) {
        this.id = id;
    }
    public String getTitle() {
        return title;
    }
    public void setTitle(String title) {
        this.title = title;
    }
    public String getContent() {
        return content;
    }
    public void setContent(String content) {
        this.content = content;
    }
    public News() {
        super();
    }
    public News(String title, String content) {
        super();
        this.title = title;
        this.content = content;
    }
    public Set<Comment> getComments() {
        return comments;
    }
    public void setComments(Set<Comment> comments) {
        this.comments = comments;
    }
    
    
}

HibernateSessionFactory.java

package com.cn.utilts;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;
import org.hibernate.service.ServiceRegistry;
import org.hibernate.boot.MetadataSources;
import org.hibernate.boot.registry.StandardServiceRegistryBuilder;

/**
 * Configures and provides access to Hibernate sessions, tied to the
 * current thread of execution.  Follows the Thread Local Session
 * pattern, see {@link http://hibernate.org/42.html }.
 */
public class HibernateSessionFactory {

    /** 
     * Location of hibernate.cfg.xml file.
     * Location should be on the classpath as Hibernate uses  
     * #resourceAsStream style lookup for its configuration file. 
     * The default classpath location of the hibernate config file is 
     * in the default package. Use #setConfigFile() to update 
     * the location of the configuration file for the current session.   
     */
    private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
    private static org.hibernate.SessionFactory sessionFactory;
    
    private static Configuration configuration = new Configuration();
    private static ServiceRegistry serviceRegistry; 

    static {
        try {
            configuration.configure();
            serviceRegistry = new StandardServiceRegistryBuilder().configure().build();
            try {
                sessionFactory = new MetadataSources(serviceRegistry).buildMetadata().buildSessionFactory();
            } catch (Exception e) {
                StandardServiceRegistryBuilder.destroy(serviceRegistry);
                e.printStackTrace();
            }
        } catch (Exception e) {
            System.err.println("%%%% Error Creating SessionFactory %%%%");
            e.printStackTrace();
        }
    }
    private HibernateSessionFactory() {
    }
    
    /**
     * Returns the ThreadLocal Session instance.  Lazy initialize
     * the <code>SessionFactory</code> if needed.
     *
     *  @return Session
     *  @throws HibernateException
     */
    public static Session getSession() throws HibernateException {
        Session session = (Session) threadLocal.get();

        if (session == null || !session.isOpen()) {
            if (sessionFactory == null) {
                rebuildSessionFactory();
            }
            session = (sessionFactory != null) ? sessionFactory.openSession()
                    : null;
            threadLocal.set(session);
        }

        return session;
    }

    /**
     *  Rebuild hibernate session factory
     *
     */
    public static void rebuildSessionFactory() {
        try {
            configuration.configure();
            serviceRegistry = new StandardServiceRegistryBuilder().configure().build();
            try {
                sessionFactory = new MetadataSources(serviceRegistry).buildMetadata().buildSessionFactory();
            } catch (Exception e) {
                StandardServiceRegistryBuilder.destroy(serviceRegistry);
                e.printStackTrace();
            }
        } catch (Exception e) {
            System.err.println("%%%% Error Creating SessionFactory %%%%");
            e.printStackTrace();
        }
    }

    /**
     *  Close the single hibernate session instance.
     *
     *  @throws HibernateException
     */
    public static void closeSession() throws HibernateException {
        Session session = (Session) threadLocal.get();
        threadLocal.set(null);

        if (session != null) {
            session.close();
        }
    }

    /**
     *  return session factory
     *
     */
    public static org.hibernate.SessionFactory getSessionFactory() {
        return sessionFactory;
    }
    /**
     *  return hibernate configuration
     *
     */
    public static Configuration getConfiguration() {
        return configuration;
    }

}

测试类Test.java

package com.cn.test;

import javax.persistence.Entity;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.AnnotationConfiguration;
import org.hibernate.cfg.Configuration;

import com.cn.pojo.Comment;
import com.cn.pojo.News;


@Entity
public class Test {
    @org.junit.Test
    public void test1(){
        Configuration configuration = new AnnotationConfiguration().configure();
        SessionFactory sessionFactory = configuration.buildSessionFactory();
        Session session = sessionFactory.openSession();
        Transaction tx = session.beginTransaction();
        try {
            News news = new News("鍐滆锤鏍囬","鍐滆锤鍐呭");
            Comment comment1 = new Comment("璇勮1銆傘?傘??");
            Comment comment2 = new Comment("璇勮2銆傘?傘??");
            comment1.setNews(news);
            comment2.setNews(news);
            session.save(comment1);
            session.save(comment2);

            tx.commit();
        } catch (Exception e) {
            tx.rollback();
            e.printStackTrace();
        }finally{
            session.close();    
        }
    }
}

检索：HQL

@org.junit.Test
    public void test1(){
        Configuration configuration = new AnnotationConfiguration().configure();
        SessionFactory sessionFactory = configuration.buildSessionFactory();
        //获取session对象
        Session session = sessionFactory.openSession();
        
        Transaction transaction = session.beginTransaction();
        
        try {
            //编写hql语句
            String hql = "from Customer c where c.name=? and c.password=?";
            //获取query对象
            Query query = session.createQuery(hql).setString(0, "xxx").setString(1, "123456");
            //动态绑定参数
            /*query.setString(0, "xxx");
            query.setString(1, "123456");*/
            //操作query
            List<Customer> customers = query.list();
            
            for(Customer customer:customers){
                System.out.println("name="+customer.getName());
            }
            
            transaction.commit();
        } catch (Exception e) {
            e.printStackTrace();
            transaction.rollback();
        } finally{
            session.close();
        }
        
    }

QBC

    @org.junit.Test
    public void test7(){
        Configuration configuration = new AnnotationConfiguration().configure();
        SessionFactory sessionFactory = configuration.buildSessionFactory();
        //获取session对象
        Session session = sessionFactory.openSession();
        
        Transaction transaction = session.beginTransaction();
        
        try {
            //select * from tb_customer
            Criteria criteria = session.createCriteria(Customer.class).add(Restrictions.like("name", "%杰")).add(Restrictions.eq("password", "123456"));
            
            //创建条件
            //name like "%杰"
            //password = "123456"
            //Criterion c1 = Restrictions.like("name", "%杰");
            //Criterion c2 = Restrictions.eq("password", "123456");
            
            //将条件添加到sql语句里
            //criteria.add(c1);
            //criteria.add(c2);
            
            List<Customer> customers = criteria.list();
            for(Customer customer:customers){
                System.out.println("name="+customer.getName());
            }
            
            transaction.commit();
        } catch (Exception e) {
            e.printStackTrace();
            transaction.rollback();
        } finally{
            session.close();
        }
        
    }