hiberante框架简单使用

一、下载相关jar

二、hibernate.cfg.xml

<!DOCTYPE hibernate-configuration PUBLIC      "-//Hibernate/Hibernate Configuration DTD 3.0//EN"      "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">    <hibernate-configuration>      <session-factory >          <!-- mysql数据库驱动 -->          <property name="hibernate.connection.driver_class">oracle.jdbc.OracleDriver</property>          <!-- mysql数据库名称 -->          <property name="hibernate.connection.url">jdbc:oracle:thin:@192.168.0.36:1521:orcl</property>          <!-- 数据库的登陆用户名 -->          <property name="hibernate.connection.username">nbis_data_ect_dev</property>          <!-- 数据库的登陆密码 -->          <property name="hibernate.connection.password">nbis_data_ect_dev</property>          <!-- 方言：为每一种数据库提供适配器，方便转换 -->          <property name="hibernate.dialect">org.hibernate.dialect.Oracle10gDialect</property>        <property name="hibernate.show_sql">true</property>                <mapping class="com.hibernate.model.Student"/>        <mapping class="com.hibernate.model.Teacher"/>

<span style="white-space:pre"></span><!-- 如果没有使用注解的情况 -->        <mapping resource="Student.hbm.xml"/>    </session-factory>      </hibernate-configuration>  

三、Student.java

package com.hibernate.model;import java.util.List;import java.util.Set;import javax.persistence.CascadeType;import javax.persistence.Column;import javax.persistence.Entity;import javax.persistence.FetchType;import javax.persistence.GeneratedValue;import javax.persistence.GenerationType;import javax.persistence.Id;import javax.persistence.OneToMany;import javax.persistence.SequenceGenerator;import javax.persistence.Table;@Entity@Table(name="t_student")public class Student {@SequenceGenerator(sequenceName="t_student_SEQ",name="idGen", allocationSize=1)@Id//@GeneratedValue(strategy=GenerationType.TABLE, generator="idGen")@GeneratedValue(strategy=GenerationType.SEQUENCE, generator="idGen")@Column(name="ID")private long id;@Column(name="NAME")private String name;@Column(name="AGE")private Integer age;@Column(name="PASSWORD")private String password;/*@OneToMany(mappedBy="std",cascade = CascadeType.ALL, fetch = FetchType.LAZY)private List<Teacher> teachers;*/public long getId() {return id;}public void setId(long id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}/*public List<Teacher> getTeachers() {return teachers;}public void setTeachers(List<Teacher> teachers) {this.teachers = teachers;}*/}

四、Teacher.java

package com.hibernate.model;import javax.persistence.*;@Entity@Table(name="t_teacher")public class Teacher {@SequenceGenerator(sequenceName="t_teacher_seq",name="idGen", allocationSize=1)@Id//@GeneratedValue(strategy=GenerationType.TABLE, generator="idGen")@GeneratedValue(strategy=GenerationType.SEQUENCE, generator="idGen")@Column(name="ID")private long id;@Column(name="NAME")private String name;@Column(name="AGE")private Integer age;@Column(name="PASSWORD")private String password;@Column(name="std_id", insertable = false, updatable = false)private long stdId;@ManyToOne(targetEntity = Student.class)@JoinColumn(name="std_id",referencedColumnName = "id")private Student std;public long getId() {return id;}public void setId(long id) {this.id = id;}public String getName() {return name;}public void setName(String name) {this.name = name;}public Integer getAge() {return age;}public void setAge(Integer age) {this.age = age;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public long getStdId() {return stdId;}public void setStdId(long stdId) {this.stdId = stdId;}public Student getStd() {return std;}public void setStd(Student std) {this.std = std;}}

五、测试类StudentTest.java

package com.hibernate.test;import java.util.ArrayList;import java.util.List;import java.util.Set;import javax.transaction.Transaction;import org.apache.commons.logging.Log;import org.hibernate.Query;import org.hibernate.Session;import org.hibernate.SessionFactory;import org.hibernate.cfg.AnnotationConfiguration;import org.hibernate.cfg.Configuration;import com.hibernate.model.Student;import com.hibernate.model.Teacher;public class StudentTest{/** * @param args * @throws Exception  */public static void main(String[] args) throws Exception {        Configuration config = new AnnotationConfiguration().configure();          SessionFactory factory = config.buildSessionFactory();                    Session session = factory.openSession();                            Student std = new Student();        std.setName("WangWu");        std.setAge(18);        std.setPassword("12345");                Teacher tea1 = new Teacher();          tea1.setName("LiPing");         tea1.setAge(45);        tea1.setPassword("12345");        tea1.setStd(std);                        try{              session.beginTransaction();             //session.save(std);              //session.save(tea1);                         Object obj = session.load(Student.class, 17l);            session.refresh(obj);            Object obj1 = session.load(Student.class, 17l);            System.out.println("load.....");                        String str= "from Teacher";            Query query = session.createQuery(str);            List<?> list = query.list();                        session.getTransaction().commit();          }catch(Exception e){          System.out.println(e);            session.getTransaction().rollback();          }finally{              session.close();              factory.close();          }  }}

使用反射模拟实现hibernate

一个对象要存进数据库中,一般需要通过JDBC连接数据库,创建SQL语句,执行execute或executeUpdate方法,

步骤很多,过程很繁琐,并且SQL语句不是面向对象的语言.

hibernate这种方式是面向对象的

.hibernate两端连接着对象和数据库,

是一种ORM对象关系映射,

通过操作对象与关系数据库建立关联,进行数据库的增删改查,

简化了编程,并且跨数据库平台,只要说明使用的方言,就会自动转换为各种数据库的操作.

模拟思路-------------

1.首先建立一个实体类.例如Student

Student.Java

 

public class Student {      private int id;      private String name;      private int age;      public int getId() {          return id;      }      public void setId(int id) {          this.id = id;      }      public String getName() {          return name;      }      public void setName(String name) {          this.name = name;      }      public int getAge() {          return age;      }      public void setAge(int age) {          this.age = age;      }        }  

 

2.建立数据库hibernate,建立表student,varchar _id primary key,varchar _name,int _age.Myeclipse中记得导入MySQL的jar包

略

3.建立一个Session类,调用save方法的时候,会根据配置文件读出对应类的内容,自动建立sql语句并执行.

建立映射,把数据库表的名字和类名对应,把数据库表的字段名和属性名对应.

Session.java

 

import java.lang.reflect.Method;  import java.sql.Connection;  import java.sql.DriverManager;  import java.sql.PreparedStatement;  import java.util.HashMap;  import java.util.Map;    public class Session {      //表名      String tableName = "_Student";      //字段名和属性名的Map集合,key为数据库中字段名,value为类中属性名,根据value可以得到所有get方法名      Map<String, String> columnsfields = new HashMap<String,String>();      String[] methodName;            //Session构造时初始化信息,如Student类初始化id,name,age属性,数据库字段为_id,_name,_age      public Session() {          columnsfields.put("_id", "id");          columnsfields.put("_name", "name");          columnsfields.put("_age", "age");          //methodName存储该类的所有get方法名.          methodName = new String[columnsfields.size()];      }      public void save(Student s) throws Exception{          String sql = createSQL();          Class.forName("com.mysql.jdbc.Driver");          Connection conn = DriverManager.getConnection("jdbc:mysql://localhost:3306/_Student","root","root");          PreparedStatement ps = conn.prepareStatement(sql);  //      ps.setXXX() = s.getXXX();           for(int i = 0 ;i<methodName.length;i++){          //根据方法名拿到方法原型.              Method m = s.getClass().getMethod(methodName[i]);              //根据返回值类型对象得到返回值类名,判断调用PrepareStatement的哪个set方法              Class returnType = m.getReturnType();              if("java.lang.String".equals(returnType.getName())){                  String v = (String) m.invoke(s);                  System.out.println(v);//zhangsan                  ps.setString(i+1,v);              }else if("int".equals(returnType.getName())){                  Integer v = (Integer) m.invoke(s);                  System.out.println(v);//1  18                  ps.setInt(i+1,v);              }              System.out.println(m.getName()+","+m.getReturnType());          }          ps.executeUpdate();      }      //拼SQL的insert语句      private String createSQL() {          //str1字段名,如_id,_age,_name          String str1 = "";          int index=0;                    for (String key : columnsfields.keySet()) {              //记录角标,得到key对应的value,截取第一个字符变为大写,前面加get,得到get方法名.              String v = columnsfields.get(key);              v = "get"+Character.toUpperCase(v.charAt(0))+v.substring(1);              methodName[index] = v;              str1 = str1 + key + ",";              index++;          }          str1 = str1.substring(0,str1.length()-1);          System.out.println(str1);//_id,_age,_name          //str2问号,如 ?,?,?          String str2 = "";          for (int i = 0; i < columnsfields.size(); i++) {              str2 = str2 + "?,";          }          str2 = str2.substring(0,str2.length()-1);          System.out.println(str2);//?,?,?          //拼出的SQL语句          String s = "insert into "+tableName+"("+str1+")"+ " values " +"("+str2+")";          System.out.println(s);//insert into _Student(_id,_age,_name) values (?,?,?)          return s;      }  }  

 

4.测试类,用于测试

TestHibernate.java

 

public class TestHibernate {            public static void main(String[] args) throws Exception {          Student s = new Student();          s.setAge(18);          s.setId(1);          s.setName("zhangsan");          Session session = new Session();          session.save(s);      }        }