由于最近在学习Hibernate时,特别是在Mac+idea16+Mysql网上的环境搭建教程比较少,另一个原因也是为了记录自己在建立Hibernate项目时所遇到的一系列问题,特此写下该文档来记录,方便自己和他人日后遇到同样的问题,能少走弯路。
由于Maven有良好的仓库管理的优点,方便导入必要Jar包,也便于用户管理本地的Jar文件,因此此次简单项目的建立如图 新建Maven项目。
由于只是简单的项目演示,不必选相应的模板,直接点Next
建立好项目后,打开Maven配置文件pom.xml
并如图,添加相应的Jar包依赖。junit 有较好的分部调试的功能,可以方便我们对部分方法的调试;其中,hibernate-core的Jar包才是该项目的核心文件。如果,本地仓库中没有,则idea会自动从远程仓库中下载相应的文件到本地仓库。(出现下不动的情况很正常,具体原因你懂得)
导入成功后。如图,在项目包,鼠标右键打开Add Framework Support为项目添加相应的框架。
打开后如图选中Hibernate,由于已从Maven中导入了相关的库,idea会自动识别。如果未识别,请手动匹配相关的库。
以上有两个可选项:
Create default hibernate configuration and main class
第一个是创建一个系统默认的hibernate的测试类(初学Hibernate时建议勾选,因为它会 给你提供相应的一些建立session的方法及帮助),勾选后会生成如下调试代码:
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| public class Main { private static final SessionFactory ourSessionFactory;
static { try { Configuration configuration = new Configuration(); configuration.configure();
ourSessionFactory = configuration.buildSessionFactory(); } catch (Throwable ex) { throw new ExceptionInInitializerError(ex); } }
public static Session getSession() throws HibernateException { return ourSessionFactory.openSession(); }
public static void main(final String[] args) throws Exception { final Session session = getSession(); try { System.out.println("querying all the managed entities..."); final Metamodel metamodel = session.getSessionFactory().getMetamodel(); for (EntityType<?> entityType : metamodel.getEntities()) { final String entityName = entityType.getName(); final Query query = session.createQuery("from " + entityName); System.out.println("executing: " + query.getQueryString()); for (Object o : query.list()) { System.out.println(" " + o); } } } finally { session.close(); } } }
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在这里为了演示,这两个都不勾选。
添加完成后,打开右上角的项目架构图标
打开后如图选中Modules —>Hibernate —> + hibernate.cfg.xml ,来添加相应的配置文件,一路ok。
由于Idea不像Eclipse可以根据写好的映射类来自动生成相应的hbm映射文件,但Idea可以根据已有的表来生成相应的hbm映射文件。
因此我们先建立数据库。
如下图设置
建立连接后,可以如图会显示该数据库中的表项目。
接下来根据相应的表来建立相应的映射类及hbm映射配置文件。
如图 ,一路OK。
并将默认生成的hbm文件手动移动到resources中,默认位置与生成的类位置相同,如果未移动,则会报错 找不到映射文件
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| org.hibernate.boot.MappingNotFoundException: Mapping (RESOURCE) not found : htest/StudentEntity.hbm.xml : origin(htest/StudentEntity.hbm.xml)
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打开生成相应的StudentEntity类,并作相应修改
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| @Entity @Table(name = "STUDENT", schema = "test_db") public class StudentEntity { private int sid; private String name; private String gender; private String address; private String phone; private Date birthday;
public StudentEntity() { }
public StudentEntity(int sid, String name, String gender, String address, String phone, Date birthday) { this.sid = sid; this.name = name; this.gender = gender; this.address = address; this.phone = phone; this.birthday = birthday; }
@Id @Column(name = "SID", nullable = false) public int getSid() { return sid; }
public void setSid(int sid) { this.sid = sid; }
@Basic @Column(name = "NAME", nullable = false, length = 45) public String getName() { return name; }
public void setName(String name) { this.name = name; }
@Basic @Column(name = "GENDER", nullable = false, length = 45) public String getGender() { return gender; }
public void setGender(String gender) { this.gender = gender; }
@Basic @Column(name = "ADDRESS", nullable = false, length = 45) public String getAddress() { return address; }
public void setAddress(String address) { this.address = address; }
@Basic @Column(name = "PHONE", nullable = false, length = 45) public String getPhone() { return phone; }
public void setPhone(String phone) { this.phone = phone; }
@Basic @Column(name = "BIRTHDAY", nullable = false) public Date getBirthday() { return birthday; }
public void setBirthday(Date birthday) { this.birthday = birthday; }
@Override public boolean equals(Object o) { if (this == o) return true; if (o == null || getClass() != o.getClass()) return false;
StudentEntity that = (StudentEntity) o;
if (sid != that.sid) return false; if (name != null ? !name.equals(that.name) : that.name != null) return false; if (gender != null ? !gender.equals(that.gender) : that.gender != null) return false; if (address != null ? !address.equals(that.address) : that.address != null) return false; if (phone != null ? !phone.equals(that.phone) : that.phone != null) return false; if (birthday != null ? !birthday.equals(that.birthday) : that.birthday != null) return false;
return true; }
@Override public int hashCode() { int result = sid; result = 31 * result + (name != null ? name.hashCode() : 0); result = 31 * result + (gender != null ? gender.hashCode() : 0); result = 31 * result + (address != null ? address.hashCode() : 0); result = 31 * result + (phone != null ? phone.hashCode() : 0); result = 31 * result + (birthday != null ? birthday.hashCode() : 0); return result; }
@Override public String toString() { return "StudentEntity{" + "sid=" + sid + ", name='" + name + '\'' + ", gender='" + gender + '\'' + ", address='" + address + '\'' + ", phone='" + phone + '\'' + ", birthday=" + birthday + '}'; } }
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同时生成相应的SrudentEntity.hbm.xml文件
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| <?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="htest.StudentEntity" table="STUDENT" schema="test_db"> <id name="sid"> <column name="SID" sql-type="int(11)"/> </id> <property name="name"> <column name="NAME" sql-type="varchar(45)" length="45"/> </property> <property name="gender"> <column name="GENDER" sql-type="varchar(45)" length="45"/> </property> <property name="address"> <column name="ADDRESS" sql-type="varchar(45)" length="45"/> </property> <property name="phone"> <column name="PHONE" sql-type="varchar(45)" length="45"/> </property> <property name="birthday"> <column name="BIRTHDAY" sql-type="date"/> </property> </class> </hibernate-mapping>
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然后修改相应的hibernate.cfg.xml文件
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| <?xml version='1.0' encoding='utf-8'?> <!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD//EN" "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> <hibernate-configuration> <session-factory>
<property name="connection.url">jdbc:mysql://127.0.0.1:3306/test_db?useSSL=false&useUnicode=true&characterEncoding=utf-8</property>
<property name="connection.driver_class">com.mysql.jdbc.Driver</property> <property name="connection.username">root</property> <property name="connection.password"></property>
<property name="hbm2ddl.auto">update</property> <property name="format_sql">true</property> <property name="show_sql">true</property> <property name="dialect">org.hibernate.dialect.MySQLDialect</property>
<mapping class="htest.StudentEntity"/> <mapping resource="StudentEntity.hbm.xml"/>
</session-factory> </hibernate-configuration>
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然后,创建测试类
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| public class StudentTest {
private SessionFactory sessionFactory; private Session session; private Transaction transaction;
@Before public void Init() { Configuration configuration = new Configuration().configure();
sessionFactory = configuration.buildSessionFactory(); session = sessionFactory.openSession(); transaction = session.beginTransaction();
}
@Test public void test() { StudentEntity student1 = new StudentEntity(20, "张三", "男", "北京", "188888888", Date.valueOf("2008-08-08"));
session.save(student1); }
@After public void destroy() { transaction.commit(); session.close(); sessionFactory.close(); } }
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运行测试类代码后,查看数据库,并更新,若写入了相应的数据则代表配置成功
有关Hibernate写入数据 中文问题
当写入中文时,报错如下
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| Dec 02, 2016 11:46:02 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions WARN: SQL Error: 1366, SQLState: HY000 Dec 02, 2016 11:46:02 PM org.hibernate.engine.jdbc.spi.SqlExceptionHelper logExceptions ERROR: Incorrect string value: '\xE5\xBC\xA0\xE4\xB8\x89' for column 'NAME' at row 1 Dec 02, 2016 11:46:02 PM org.hibernate.engine.jdbc.batch.internal.AbstractBatchImpl release INFO: HHH000010: On release of batch it still contained JDBC statements Dec 02, 2016 11:46:02 PM org.hibernate.internal.ExceptionMapperStandardImpl mapManagedFlushFailure ERROR: HHH000346: Error during managed flush [org.hibernate.exception.GenericJDBCException: could not execute statement]
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博主是通过MySQLWorkbench来建的表,如果出现下面的错误,主要有2个原因
1.检查hibernate.cfg.xml中url是否强调为utf-8
2.检查MySQL默认的编码是否为utf-8
解决办法:
原因1:在相应的URL中添加useUnicode=true&characterEncoding=utf-8 。
原因2:如图在MySQLWorkbench中修改(或在创建表时 明确为UTF-8)