Hibernate学习总结一之单表CRUD操作

Hibernate的优/缺点

优点：1.Hibernate是一个没有侵入性的框架，没有侵入性的框架我们称为轻量级框架。

           2.更加对象化  3.移植性 4.Hibernate代码测试方便。  5.提高效率，提高生产力。

缺点： 1.使用数据库特性的语句，将很难调优 

            2.对大批量数据更新存在问题

            3.系统中存在大量的攻击查询功能

Hibernate六大核心接口

     1.Configuration接口:负责配置并启动Hibernate

     2.SessionFactory接口:负责初始化Hibernate

     3.Session接口:负责持久化对象的CRUD操作

     4.Transaction接口:负责事务

     5.Query接口和Criteria接口:负责执行各种数据库查询

注意：Configuration实例是一个启动期间的对象，一旦SessionFactory创建完成它就被丢弃了。

所需Hibernate包的链接：https://pan.baidu.com/s/10CQ_FvSkagqLG_JU0KBjHg 
提取码：sl72 

1.主映射文件hibernate.cfg.xml

<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE hibernate-configuration PUBLIC
          "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
          "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<!-- Generated by MyEclipse Hibernate Tools.                   -->
<hibernate-configuration>

	<session-factory>
		<property name="dialect">
			org.hibernate.dialect.MySQLDialect
		</property>
		<property name="connection.url">
			jdbc:mysql://localhost:3306/hibernate_emp1?characterEncoding=utf-8
		</property>
		<property name="connection.username">root</property>
		<property name="connection.password"></property>
		<property name="connection.driver_class">
			com.mysql.jdbc.Driver
		</property>
		<!-- 显示hql语句 -->
		<property name="show_sql">true</property>
		<property name="format_sql">true</property>
		<!-- 映射文件 -->
		<mapping resource="com/aiit/pojo/TblEmp.hbm.xml" />

	</session-factory>

</hibernate-configuration>

2.封装hibernate.cfg.xml

package com.aiit.utils;

import org.hibernate.HibernateException;
import org.hibernate.Session;
import org.hibernate.cfg.Configuration;


public class HibernateSessionFactory {

	private static final ThreadLocal<Session> threadLocal = new ThreadLocal<Session>();
    private static org.hibernate.SessionFactory sessionFactory;
	
    private static Configuration configuration = new Configuration();
    private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";
    private static String configFile = CONFIG_FILE_LOCATION;

	static {
    	try {
			configuration.configure(configFile);
			sessionFactory = configuration.buildSessionFactory();
		} catch (Exception e) {
			System.err.println("%%%% Error Creating SessionFactory %%%%");
			e.printStackTrace();
		}
    }
    private HibernateSessionFactory() {
    }
	

    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;
    }


	public static void rebuildSessionFactory() {
		try {
			configuration.configure(configFile);
			sessionFactory = configuration.buildSessionFactory();
		} catch (Exception e) {
			System.err.println("%%%% Error Creating SessionFactory %%%%");
			e.printStackTrace();
		}
	}


    public static void closeSession() throws HibernateException {
        Session session = (Session) threadLocal.get();
        threadLocal.set(null);

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


	public static org.hibernate.SessionFactory getSessionFactory() {
		return sessionFactory;
	}


	public static void setConfigFile(String configFile) {
		HibernateSessionFactory.configFile = configFile;
		sessionFactory = null;
	}

	public static Configuration getConfiguration() {
		return configuration;
	}

}

3.员工类TblEmp.java

package com.aiit.pojo;

public class TblEmp implements java.io.Serializable {

	// Fields

	private Integer empId;
	private String empName;

	// Constructors
	/** default constructor */
	public TblEmp() {
	}

	/** full constructor */
	public TblEmp(String empName) {
		this.empName = empName;
	}

	// Property accessors

	public Integer getEmpId() {
		return this.empId;
	}

	public void setEmpId(Integer empId) {
		this.empId = empId;
	}

	public String getEmpName() {
		return this.empName;
	}

	public void setEmpName(String empName) {
		this.empName = empName;
	}

}

4.类的映射文件TblEmp.hbm.xml

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<!-- 
    Mapping file autogenerated by MyEclipse Persistence Tools
-->
<hibernate-mapping>
    <class name="com.aiit.pojo.TblEmp" table="tbl_emp" catalog="hibernate_emp1">
       <!-- 类属性名和数据库表字段名进行映射 -->
       <!--id name指类的主属性名，type属性类型  -->
        <id name="empId" type="java.lang.Integer">
        <!--column name指对应的数据库表字段名  -->
            <column name="empId" />
            <!-- generator 主键 设置 -->
            <generator class="identity" />
        </id>
        <property name="empName" type="java.lang.String">
            <column name="empName" />
        </property>
    </class>
</hibernate-mapping>

5.单元测试类TestEmp.java

package com.aiit.test;

import java.util.List;

import org.hibernate.Session;
import org.hibernate.Transaction;
import org.junit.After;
import org.junit.AfterClass;
import org.junit.Before;
import org.junit.BeforeClass;
import org.junit.Test;

import com.aiit.pojo.TblEmp;
import com.aiit.utils.HibernateSessionFactory;



public class TestEmp {
	static Session session;
	static Transaction tx;
	@BeforeClass
	public static void setUpBeforeClass() throws Exception {
		session = HibernateSessionFactory.getSession();
		tx = (Transaction) session.beginTransaction();
	}

	@AfterClass
	public static void tearDownAfterClass() throws Exception {
		session.close();
	}

	@Before
	public void setUp() throws Exception {
	}

	@After
	public void tearDown() throws Exception {
	}

	@Test
	public void selectOne() {
		//查询
		TblEmp emp = (TblEmp) session.get(TblEmp.class, 1);
		System.out.println(emp.getEmpName());
	}
	@Test
	public void addEmp() {
		//添加
		TblEmp emp2=new TblEmp("ait1");		
		tx.begin();
		session.save(emp2);
		tx.commit();
	}
	@Test
	public void selectAll() {
		//查询所有
		String hql = "from TblEmp";//from 类名,这里不再使用sql，实现编码语言与后台数据库分离。
		List<TblEmp> emps = session.createQuery(hql).list();
		for(TblEmp emp :emps){
			System.out.println("工号"+emp.getEmpId()+"姓名"+emp.getEmpName());
		}
	}
	@Test
	public void selectWhere() {
		//条件查询
		String hql = "from TblEmp as emp where emp.empId>2";
		List<TblEmp> emps = session.createQuery(hql).list();
		for(TblEmp emp :emps){
			System.out.println("工号"+emp.getEmpId()+"姓名"+emp.getEmpName());
		}
	}
	@Test
	public void selectSql() {
		//sql语句查询
		String sql = "SELECT * FROM tbl_emp";
		List<Object> emps = session.createSQLQuery(sql).list();
		for(int i = 0;i<emps.size();i++){
			Object[] employee = (Object[]) emps.get(i);
			System.out.println(employee[0]+","+employee[1]);

		}	
	}
	@Test
	public void deleteOne() {
		//删除
		TblEmp emp = (TblEmp) session.get(TblEmp.class, 2);
		tx.begin();
		session.delete(emp);
		tx.commit();
	}
	@Test
	public void UpdateOne() {
		//修改
		TblEmp emp = (TblEmp) session.get(TblEmp.class, 2);
		emp.setEmpName("北方");
		tx.begin();
		session.update(emp);
		tx.commit();
	}
}

6.数据库SQL

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for tbl_emp
-- ----------------------------
DROP TABLE IF EXISTS `tbl_emp`;
CREATE TABLE `tbl_emp`  (
  `empId` int(11) NOT NULL AUTO_INCREMENT,
  `empName` varchar(255) CHARACTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT NULL,
  PRIMARY KEY (`empId`) USING BTREE
) ENGINE = InnoDB AUTO_INCREMENT = 5 CHARACTER SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

-- ----------------------------
-- Records of tbl_emp
-- ----------------------------
INSERT INTO `tbl_emp` VALUES (1, '北方');
INSERT INTO `tbl_emp` VALUES (2, '小明');
INSERT INTO `tbl_emp` VALUES (3, '小红');
INSERT INTO `tbl_emp` VALUES (4, 'AIIT');

SET FOREIGN_KEY_CHECKS = 1;