接下來我們就可以來進行我們的實體開發了:
User.java
<span style="font-size:14px;">package toone.com.cn.bo;
import java.util.Date;
public class User {
private int id;//必須有主鍵,因爲hibernate很多方法都需要用到主鍵id
private String name;
private Date birthday;//必須提供默認的構造方法,這裏沒有,但是所有類都帶有默認的構造方法;</span></span>
<pre name="code" class="java"><span style="font-size:14px;"><span style="font-size:14px;"> 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 Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
}</span>
<span style="font-size:14px;"><span style="font-family: Arial; line-height: 26px;">User.hbm.xml(映射文件)</span>
</span>
<span style="font-family: Arial; line-height: 26px;"><span style="font-size:14px;"></span></span><pre name="code" class="html"><span style="font-size:14px;"><hibernate-mapping package="toone.com.cn.bo.domain">
<class name="User" table="user"><!--這裏的table值對應數據庫中的表名;如果沒有table值,默認等於類名小寫 -->
<id name="id" column="id">
<span style="white-space:pre"> </span><generator class="native"></generator><!--採用主鍵自增長方式-->
</id>
<property name="name" column="name"/><!-- 這裏的column值對應數據庫中的屬性名;如果沒有column值,默認等於屬性名 -->
<property name="birthday" column="birthday"/>
</class>
</hibernate-mapping></span>
<span style="font-family: Arial; line-height: 26px; white-space: pre;">Main.java</span>
<span style="font-family: Arial; line-height: 26px; white-space: pre;"></span><pre name="code" class="html"><span style="font-size:14px;">package toone.com.cn;
import java.util.Date;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import toone.com.cn.bo.User;
public class Main {
public static void main(String[] args){
//這裏千萬注意,不能寫成Configuration cfg = new Configuration();否則會報Hibernate Dialect must be explicitly set 錯誤信息將我們誤導
//;實際上前面我們已經配置了mysql的方言;
Configuration cfg = new Configuration().configure();//對於configure()方法,我們可以引入其源代碼進行查看,其會在類路
//徑下自動去加載一個默認的hibernate.cfg.xml文件;如果我們想換其他名字,可以使用其重載方法,具體可以查看其源代碼(下載的壓縮包中有)
SessionFactory factory = cfg.buildSessionFactory();
User user = new User();
user.setName("Kobi");
user.setBirthday(new Date());
Session session = null;
Transaction tx = null;
try {
session = factory.openSession();
tx = session.beginTransaction();//開啓事務
session.save(user);//進行保存
tx.commit();//提交事務
} catch (HibernateException e) {
if(tx!=null){
tx.rollback();//回滾事務
}
throw e;//必須拋出異常
}finally{
if(session!=null){
session.close();//關閉session
}
}
}
}</span>
<span style="font-family: Arial; line-height: 26px; white-space: pre;">HibernateUtils.java</span>
<span style="font-family: Arial; line-height: 26px; white-space: pre;"></span><pre name="code" class="html"><span style="font-size:14px;">package toone.com.cn.util;
import java.io.Serializable;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
public class HibernateUtils {
private static SessionFactory sessionfactory;
private HibernateUtils(){}
static{
Configuration cfg = new Configuration().configure();
sessionfactory = cfg.buildSessionFactory();
}
public static Session getSession(){
return sessionfactory.openSession();
}
//添加
public static void add(Object obj){
Session session = null;
Transaction tx = null;
try {
session = HibernateUtils.getSession();
tx = session.beginTransaction();
session.save(obj);//區別:save()方法如果沒有開啓事務,它會執行一條插入語句,但之後由於沒有提交事務,它又進行
//session.persist(obj);//回滾了,而persist()方法在沒有開啓事務的時候,它根本不會去執行,即沒有那條插入語句
tx.commit();
}finally{
if(session!=null){
session.close();
}
}
}
//修改
public static void update(Object obj){
Session session = null;
Transaction tx = null;
try {
session = HibernateUtils.getSession();
tx = session.beginTransaction();
session.update(obj);
tx.commit();
}finally{
if(session!=null){
session.close();
}
}
}
//刪除
public static void delete(Object obj){
Session session = null;
Transaction tx = null;
try {
session = HibernateUtils.getSession();
tx = session.beginTransaction();
session.delete(obj);
tx.commit();
}finally{
if(session!=null){
session.close();
}
}
}
//查找 不需要開啓事務
public static Object findById(Class clazz,Serializable id){
Session session = null;
try {
session = HibernateUtils.getSession();
//這裏需要區分一下get()與load()的區別,load()不會立即//去訪問數據庫只有在第一次使用的時候纔會去加載(懶加載);
//load方法永遠不可能返回空對象(如果不存在,其會產生一個user的子類)具體可以去查資料區別這兩個方法
//Object obj = session.load(clazz, id);
Object obj = session.get(clazz, id);return obj;}finally{if(session!=null){session.close();}}}}
</span>
<p style="margin-top: 0px; margin-bottom: 0px; padding-top: 0px; padding-bottom: 0px; font-family: Arial; line-height: 26px;"><span style="white-space: pre;">最後,一個實體的增刪改查操作就完成了,下面我們可以重寫Main.java文件來使用HibernateUtils工具類來對實體進行操作了:</span></p><p style="margin-top: 0px; margin-bottom: 0px; padding-top: 0px; padding-bottom: 0px; font-family: Arial; line-height: 26px;"><span style="white-space: pre;">Main.java</span></p><p style="margin-top: 0px; margin-bottom: 0px; padding-top: 0px; padding-bottom: 0px; font-family: Arial; line-height: 26px;"><span style="white-space: pre;"></span><pre name="code" class="html"><span style="font-size:14px;">package toone.com.cn;
import java.util.Date;
import toone.com.cn.bo.User;
import toone.com.cn.util.HibernateUtils;
public class Main {
public static void main(String[] args){
User user = new User();
user.setName("Kobi");
user.setBirthday(new Date());
HibernateUtils.add(user);//添加
user.setName("Jams");
HibernateUtils.update(user);//修改
HibernateUtils.delete(user);//刪除
User user1 = (User) HibernateUtils.findById(User.class, user.getId());//查找
System.out.println(user1.getName());
}
}</span>
總結:瞭解了Hibernate的基本作用,學會了使用其來進行增刪改查操作,算是工作之餘的一點收穫吧,以後還得繼續堅持發帖,不斷學習!