Hibernate学习六----------CRUD

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实例

1.项目结构

2.pom.xml

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">

  	<modelVersion>4.0.0</modelVersion>

	<groupId>org.hibernate</groupId>
	<artifactId>Hibernate-CRUD</artifactId>
	<packaging>war</packaging>
	<version>0.0.1-SNAPSHOT</version>
	<name>Hibernate-CRUD Maven Webapp</name>
	<url>http://maven.apache.org</url>

	<properties>
		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
		<hibernate.version>5.1.6.Final</hibernate.version>
	</properties>

	<dependencies>
		<!-- Junit -->
		<dependency>
			<groupId>junit</groupId>
			<artifactId>junit</artifactId>
			<version>4.12</version>
			<scope>test</scope>
		</dependency>
		<!-- hibernate -->
		<dependency>
		    <groupId>org.hibernate</groupId>
		    <artifactId>hibernate-core</artifactId>
		    <version>${hibernate.version}</version>
		</dependency>
		<!-- MySQL -->
		<dependency>
		    <groupId>mysql</groupId>
		    <artifactId>mysql-connector-java</artifactId>
		    <version>5.1.42</version>
		</dependency>
	</dependencies>

	<build>
		<finalName>Hibernate-CRUD</finalName>
	</build>
</project>

3.Student.java

package org.hibernate.model;

import java.util.Date;

public class Student {

	private long sid;// 学号
	private String sname;// 姓名
	private String gender;// 性别
	private Date birthday;// 生日
	private String address;// 地址

	public Student() {
	}

	public Student(String sname, String gender, Date birthday, String address) {
		this.sname = sname;
		this.gender = gender;
		this.birthday = birthday;
		this.address = address;
	}

	public long getSid() {
		return sid;
	}

	public void setSid(long sid) {
		this.sid = sid;
	}

	public String getSname() {
		return sname;
	}

	public void setSname(String sname) {
		this.sname = sname;
	}

	public String getGender() {
		return gender;
	}

	public void setGender(String gender) {
		this.gender = gender;
	}

	public Date getBirthday() {
		return birthday;
	}

	public void setBirthday(Date birthday) {
		this.birthday = birthday;
	}

	public String getAddress() {
		return address;
	}

	public void setAddress(String address) {
		this.address = address;
	}

	@Override
	public String toString() {
		return "Student [sid=" + sid + ", sname=" + sname + ", gender=" + gender + ", birthday=" + birthday
				+ ", address=" + address + "]";
	}

}

4.Student.hbm.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
        "-//Hibernate/Hibernate Mapping DTD 3.0//EN"
        "http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>

	<class name="org.hibernate.model.Student" table="STUDENT">
		<id name="sid" type="java.lang.Long">
			<column name="SID"/>
			<generator class="native"/>
		</id>
		<property name="sname" type="java.lang.String">
			<column name="SNAME"/>
		</property>
		<property name="gender" type="java.lang.String">
			<column name="GENDER"/>
		</property>
		<property name="birthday" type="date">
			<column name="BIRTHDAY"/>
		</property>
		<property name="address" type="java.lang.String">
			<column name="ADDRESS"/>
		</property>
	</class>

</hibernate-mapping>

5.hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC
	"-//Hibernate/Hibernate Configuration DTD 3.0//EN"
	"http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd">
<hibernate-configuration>

	<!-- SessionFactory相关配置 -->
	<session-factory>
		<!-- 数据库连接相关配置 -->
		<property name="connection.username">root</property>
		<property name="connection.password">***</property>
		<property name="connection.driver_class">com.mysql.jdbc.Driver</property>
		<property name="connection.url">
			jdbc:mysql:///hibernate?useSSL=true&amp;characterEncoding=UTF-8
		</property>
		<!-- 常用配置 -->
		<property name="dialect">org.hibernate.dialect.MySQL5InnoDBDialect</property>
		<property name="hbm2ddl.auto">update</property>
		<property name="show_sql">true</property>
		<property name="format_sql">true</property>
		<!-- 引入映射文件 -->
		<mapping resource="hbm/Student.hbm.xml"/>
	</session-factory>

</hibernate-configuration>

6.TestCRUD.java

package org.hibernate.test;

import java.util.Date;

import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.model.Student;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;

public class TestCRUD {

	private SessionFactory sessionFactory;
	private Session session;
	private Transaction transaction;

	@Before
	public void before() {

		Configuration config = new Configuration().configure();// 加载配置信息
		sessionFactory = config.buildSessionFactory();// 创建SessionFactory对象
		session = sessionFactory.openSession();// 创建Session对象
		transaction = session.beginTransaction();// 开启事务

	}

	@After
	public void after() {

		transaction.commit();// 提交事务
		session.close();// 关闭Session
		sessionFactory.close();// 关闭SessionFactory

	}

	@Test
	public void testCreate() {

		Student student = new Student("张三", "男", new Date(), "北京市");// 创建Student对象
		session.save(student);// 保存对象

	}

	@Test
	public void testRetrieveByGet() {

		Student student = session.get(Student.class, 1L);// 通过get查询信息
		System.out.println(student);

	}

	@Test
	public void testRetrieveByLoad() {

		Student student = session.load(Student.class, 1L);// 通过load查询信息
		System.out.println(student);

	}

	@Test
	public void testUpdate() {

		Student student = session.load(Student.class, 1L);// 通过load查询信息
		student.setAddress("上海市");// 修改信息
		session.update(student);// 保存修改信息

	}

	@Test
	public void testDelete() {

		Student student = session.load(Student.class, 1L);// 通过load查询信息
		session.delete(student);// 删除信息

	}

}

7.效果预览

　　7.1 执行testCreate()方法

　　7.2 执行testRetrieveByGet()方法（带输出语句）

　　7.3 执行testRetrieveByGet()方法（不带输出语句）

　　7.4 执行testRetrieveByGet()方法（将主键由1L改为2L）

@Test
public void testRetrieveByGet() {

	Student student = session.get(Student.class, 2L);// 通过get查询信息
	System.out.println(student);

}

　　

　　7.5 执行testRetrieveByLoad()方法（带输出语句）

　　7.6 执行testRetrieveByLoad()方法（不带输出语句）

　　7.7 执行testRetrieveByLoad()方法（将主键由1L改为2L）

@Test
public void testRetrieveByLoad() {

	Student student = session.load(Student.class, 2L);// 通过load查询信息
	System.out.println(student);

}

　　7.8 执行testUpdate()方法

　　7.9 执行testDelete()方法

8.总结　

　　- get和load的区别

　　　　1.在不考虑缓存的情况下，get方法会在调用之后立即向数据库发出SQL语句，返回持久化对象；load方法会在调用后返回一个代理对象，该代理对象只保存了实体对象的id，直到使用对象的非主键属性时才会发出SQL语句

　　　　2. 查询数据不存在的数据时，get方法返回null，load方法抛出异常org.hibernate.ObjectNotFoundException

参考：http://www.imooc.com/video/7742