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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&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