hibernate注解步骤

Hibernate注解的作用是不要另外再写与实体类关联的映射xml文件

第一步：导入Hibernate 和 数据库 的Jar包至项目中WebRoot/WEB-INF/lib

第二步：在项目中的src目录写hibernate.cfg.xml(与数据库创建连接在这实现)

<?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">

<hibernate-configuration>

<session-factory>
<property name="dialect">
org.hibernate.dialect.MySQLDialect
</property>
<property name="connection.url">
jdbc:mysql://localhost:3306/chose?characterEncoding=utf-8
</property>
<property name="connection.username">root</property>
<property name="connection.password">123456</property>
<property name="connection.driver_class">
com.mysql.jdbc.Driver
</property>
<property name="show_sql">true</property><!--后台显示sql语句,fail为不显示sql语句-->
<mapping resource="com/hib/test/Course.xml" /><!-- 映射与实体类关联的xml文件 -->
<mapping class="com.hib.test.User" /><!--   映射注解的实体类--> </session-factory>
</hibernate-configuration>


第三步：创建实体类
与数据库关联的类叫做实体类

package com.hib.test;


public class User {

private Long id;

private String username;

private String password;


public Long getId() {
return id;
}

public void setId(Long id) {
this.id = id;
}

public String getUsername() {
return username;
}

public void setUsername(String username) {
this.username = username;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}

}

第四步：在创建的实体类中使用hibernate注解
package com.hib.test;

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Table;

//hibernate注解
@Entity
@Table(name = "t_user")

public class User {

private Long id;

private String username;

private String password;

@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)  //主键自增的方式                                                              
public Long getId() {
return id;
}

public void setId(Long id) {
this.id = id;
}

@Column(name = "username")                                                         
         public String getUsername() {
return username;
}

public void setUsername(String username) {
this.username = username;
}

@Column(name = "password")
public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}

}
注意：
1、如果在实体类的类名和关联的数据库表名相同，注解可写成：
@Entity
@Table
2、如果在实体类声明的属性与所要关联数据库表的字段相同，注解可写成：
@Column
第五步：在hibernate.cfg.xml中映射实体类

<?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">

<hibernate-configuration>

<session-factory>
<property name="dialect">
org.hibernate.dialect.MySQLDialect
</property>
<property name="connection.url">
jdbc:mysql://localhost:3306/chose?characterEncoding=utf-8
</property>
<property name="connection.username">root</property>
<property name="connection.password">123456</property>
<property name="connection.driver_class">
com.mysql.jdbc.Driver
</property>
<property name="show_sql">true</property><!--后台显示sql语句,fail为不显示sql语句-->
                     
  <mapping resource="com/hib/test/Course.xml" /><!-- 映射与实体类关联的xml文件 -->

<mapping class="com.hib.test.User" /><!--- 映射注解的实体类--> </session-factory>
</hibernate-configuration>