Hibernate学习(第一天)--CURD
Hibernate实现对象的增删改查
Hibernate是一个面向Java环境的对象/关系数据库映射工具，用来把对象模型表示的对象映射到基于SQL的关系模型数据结构中去。
Hibernate的优势:开源免费;轻量级封装;可拓展性;稳定发展。
使用步骤:
1,新建Java/WEB工程.
new-->Web Project -->填写工程名.
2,在工程上右键-->myEclipse-->Add Hibernate Capabilities --> 选择Hibernate版本号 --> Next --> 选择数据库类型 --> Next --> 选择JavaPackage --> Finish.(生成两个与Hibernate相关的文件:hibernate.cfg.xml,HibernateSessionFactory.java)
3,生成映射类和映射文件:
切换到DB,选择表,右键 --> Hibernate Reverse Engineering.. --> 选择需要生成的文件(实体类,映射文件,dao) --> Generation Id 选择native-->Finish.
4,自己写Dao方法.
代码如下,
接口类:BaseDao
package com.justplay.dao;
import java.util.List;
public interface BaseDao {
public void save(Object o);
public void update(Object o);
public void delete(Object o);
public Object get(Class<?> clazz, long id);
public List<?> list(String hql);
}
实现类:BaseDaoImpl
package com.justplay.dao.impl;
import java.util.List;
import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.Transaction;
import com.justplay.dao.BaseDao;
import com.justplay.util.HibernateSessionFactory;
public class BaseDaoImpl implements BaseDao {
public void save(Object o) {
Session session = HibernateSessionFactory.getSession();
Transaction tr = session.beginTransaction();
try {
session.save(o);
tr.commit();
} catch (HibernateException e) {
e.printStackTrace();
}finally{
HibernateSessionFactory.closeSession();
}
}
public void update(Object o) {
Session session = HibernateSessionFactory.getSession();
Transaction tr = session.beginTransaction();
try {
session.update(o);
tr.commit();
} catch (HibernateException e) {
e.printStackTrace();
}finally{
HibernateSessionFactory.closeSession();
}
}
public void delete(Object o) {
Session session = HibernateSessionFactory.getSession();
Transaction tr = session.beginTransaction();
try {
session.delete(o);
tr.commit();
} catch (HibernateException e) {
e.printStackTrace();
}finally{
HibernateSessionFactory.closeSession();
}
}
public Object get(Class<?> clazz, long id) {
Session session = HibernateSessionFactory.getSession();
try {
return session.get(clazz, id);
} catch (HibernateException e) {
e.printStackTrace();
}finally{
HibernateSessionFactory.closeSession();
}
return null;
}
public List<?> list(String hql) {
Session session = HibernateSessionFactory.getSession();
try {
return session.createQuery(hql).list();
} catch (HibernateException e) {
e.printStackTrace();
}finally{
HibernateSessionFactory.closeSession();
}
return null;
}
}
测试类TestBaseDaoImpl:
package test;
import java.util.List;
import junit.framework.TestCase;
import com.justplay.dao.BaseDao;
import com.justplay.po.User;
public class TestBaseDaoImpl extends TestCase {
BaseDao dao;
protected void setUp() throws Exception {
dao = new com.justplay.dao.impl.BaseDaoImpl();
}
protected void tearDown() throws Exception {
super.tearDown();
}
public void testSave() {
User u = new User();
u.setUsername("Tom");
u.setPassword("1234");
dao.save(u);
}
public void testUpdate() {
User u = (User) dao.get(User.class, 2);
u.setUsername("Lucy");
u.setPassword("2345");
dao.update(u);
}
public void testDelete() {
}
public void testGet() {
System.out.println(dao.get(User.class, 1));
}
public void testList() {
List<?> list = dao.list("from User");
System.out.println(list.size());
}
}
给出实体类吧:
User
package com.justplay.po;
/**
* User entity. @author MyEclipse Persistence Tools
*/
public class User implements java.io.Serializable {
// Fields
private static final long serialVersionUID = 1L;
private Long id;
private String password;
private String username;
// Constructors
/** default constructor */
public User() {
}
/** full constructor */
public User(String password, String username) {
this.password = password;
this.username = username;
}
// Property accessors
public Long getId() {
return this.id;
}
public void setId(Long id) {
this.id = id;
}
public String getPassword() {
return this.password;
}
public void setPassword(String password) {
this.password = password;
}
public String getUsername() {
return this.username;
}
public void setUsername(String username) {
this.username = username;
}
@Override
public String toString() {// 方便测试
return "User [id=" + id + ", password=" + password + ", username="
+ username + "]";
}
}
如果觉得 BaseDao中的方法太多,可以换种方式: UserDaoImpl
package com.justplay.dao.impl;
import com.justplay.dao.UserDao;
import com.justplay.po.User;
// 继承BaseDaoImpl(可以不用继续写实现方法了),实现UserDao
public class UserDaoImpl extends BaseDaoImpl implements UserDao {
public void save(User u) {
super.save(u);
}
}
UserDao
package com.justplay.dao;
import com.justplay.po.User;
public interface UserDao {
public void save(User u);
}
测试类TestUserDaoImpl:
package test;
import junit.framework.TestCase;
import com.justplay.dao.UserDao;
import com.justplay.dao.impl.UserDaoImpl;
import com.justplay.po.User;
public class TestUserDaoImpl extends TestCase {
UserDao dao;
protected void setUp() throws Exception {
dao = new UserDaoImpl();
}
protected void tearDown() throws Exception {
super.tearDown();
}
public void testSaveUser() {
User u = new User();
u.setPassword("1234");
u.setUsername("Jack");
dao.save(u);
}
}