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這篇文章給大家介紹在Java應(yīng)用中使用Hibernate的示例分析,內(nèi)容非常詳細(xì),感興趣的小伙伴們可以參考借鑒,希望對(duì)大家能有所幫助。
一、在Java應(yīng)用中使用Hibernate的步驟
創(chuàng)建Hibernate的配置文件
創(chuàng)建持久化類
創(chuàng)建對(duì)象-關(guān)系映射文件
通過Hibernate API編寫訪問數(shù)據(jù)庫的代碼
二、Helloapp應(yīng)用的結(jié)構(gòu)
三、Hibernate的配置文件(hibernate.properties)
hibernate.dialect=org.hibernate.dialect.MySQLDialect hibernate.connection.driver_class=com.mysql.jdbc.Driver hibernate.connection.url=jdbc:mysql://localhost:3306/SAMPLEDB hibernate.connection.username=root hibernate.connection.password=1234 hibernate.show_sql=true
四、創(chuàng)建持久化類Customer
持久化類符合JavaBean的規(guī)范,包含一些屬性,以及與之對(duì)應(yīng)的getXXX()和setXXX()方法。
持久化類有一個(gè)id屬性,用來惟一標(biāo)識(shí)Customer類的每個(gè)對(duì)象。在面向?qū)ο笮g(shù)語中,這個(gè)id屬性被稱為對(duì)象標(biāo)識(shí)符(OID,Object Identifier),通常它都用整數(shù)表示
Hibernate要求持久化類必須提供一個(gè)不帶參數(shù)的默認(rèn)構(gòu)造方法
package mypack; import java.io.Serializable; import java.sql.Date; import java.sql.Timestamp; public class Customer implements Serializable { private Long id; private String name; private String email; private String password; private int phone; private String address; private char sex; private boolean married; private String description; private byte[] image; private Date birthday; private Timestamp registeredTime; public Customer(){} public Long getId(){ return id; } private void setId(Long id){ this.id = id; } public String getName(){ return name; } public void setName(String name){ this.name=name; } public String getEmail(){ return email; } public void setEmail(String email){ this.email =email ; } public String getPassword(){ return password; } public void setPassword(String password){ this.password =password ; } public int getPhone(){ return phone; } public void setPhone(int phone){ this.phone =phone ; } public String getAddress(){ return address; } public void setAddress(String address){ this.address =address ; } public char getSex(){ return sex; } public void setSex(char sex){ this.sex =sex ; } public boolean isMarried(){ return married; } public void setMarried(boolean married){ this.married =married ; } public String getDescription(){ return description; } public void setDescription(String description){ this.description =description ; } public byte[] getImage() { return this.image; } public void setImage(byte[] image) { this.image = image; } public Date getBirthday() { return this.birthday; } public void setBirthday(Date birthday) { this.birthday = birthday; } public Timestamp getRegisteredTime() { return this.registeredTime; } public void setRegisteredTime(Timestamp registeredTime) { this.registeredTime = registeredTime; } }
注意:
getXXX()和setXXX()方法可以采用任意的訪問級(jí)別,他的命名規(guī)則必須符合特定的命名規(guī)則,“get”和“set”后面緊跟屬性的名字,并且屬性名的首字母為大寫,如name屬性的get方法為getName()。
如果持久化類的屬性為boolean類型,那么它的get方法名可以用get做前綴也可以用is做前綴。
五、創(chuàng)建數(shù)據(jù)庫Schema
drop database if exists SAMPLEDB; create database SAMPLEDB; use SAMPLEDB; create table CUSTOMERS ( ID bigint not null primary key, NAME varchar(15) not null, EMAIL varchar(128) not null, PASSWORD varchar(8) not null, PHONE int , ADDRESS varchar(255), SEX char(1) , IS_MARRIED bit, DESCRIPTION text, IMAGE blob, BIRTHDAY date, REGISTERED_TIME timestamp );
六、創(chuàng)建對(duì)象-關(guān)系映射文件Customer.hbm.xml
<?xml version="1.0"?> <!DOCTYPE hibernate-mapping PUBLIC"-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd"> <hibernate-mapping> <class name="mypack.Customer" table="CUSTOMERS"> <id name="id" column="ID" type="long"> <generator class="increment"/> </id> <property name="name" column="NAME" type="string" not-null="true" /> <property name="email" column="EMAIL" type="string" not-null="true" /> <property name="password" column="PASSWORD" type="string" not-null="true"/> <property name="phone" column="PHONE" type="int" /> <property name="address" column="ADDRESS" type="string" /> <property name="sex" column="SEX" type="character"/> <property name="married" column="IS_MARRIED" type="boolean"/> <property name="description" column="DESCRIPTION" type="text"/> <property name="image" column="IMAGE" type="binary"/> <property name="birthday" column="BIRTHDAY" type="date"/> <property name="registeredTime" column="REGISTERED_TIME" type="timestamp"/> </class> </hibernate-mapping>
<id>元素映射OID
<generator>子元素用來設(shè)定標(biāo)識(shí)符生成器。Hibernate提供了提供了多種內(nèi)置的實(shí)現(xiàn)。
<property>元素映射值類型屬性
name屬性:指定持久化類的屬性的名字。
column屬性:指定與類的屬性映射的表的字段名。
type屬性:指定Hibernate映射類型。Hibernate映射類型是Java類型與SQL類型的橋梁。
采用XML文件來配置對(duì)象-關(guān)系映射的優(yōu)點(diǎn):
Hibernate既不會(huì)滲透到上層域模型中,也不會(huì)滲透到下層數(shù)據(jù)模型中。
軟件開發(fā)人員可以獨(dú)立設(shè)計(jì)域模型,不必強(qiáng)迫遵守任何規(guī)范。
數(shù)據(jù)庫設(shè)計(jì)人員可以獨(dú)立設(shè)計(jì)數(shù)據(jù)模型,不必強(qiáng)迫遵守任何規(guī)范。
對(duì)象-關(guān)系映射不依賴于任何程序代碼,如果需要修改對(duì)象-關(guān)系映射,只需修改XML文件,不需要修改任何程序,提高了軟件的靈活性,并且使維護(hù)更加方便。
七、創(chuàng)建BusinessService類
package mypack; import javax.servlet.*; import org.hibernate.*; import org.hibernate.cfg.Configuration; import java.io.*; import java.sql.Date; import java.sql.Timestamp; import java.util.*; public class BusinessService{ public static SessionFactory sessionFactory; /** 初始化Hibernate,創(chuàng)建SessionFactory實(shí)例 */ static{ try{ // 根據(jù)默認(rèn)位置的Hibernate配置文件的配置信息,創(chuàng)建一個(gè)Configuration實(shí)例 Configuration config = new Configuration(); //加載Customer類的對(duì)象-關(guān)系映射文件 config.addClass(Customer.class); // 創(chuàng)建SessionFactory實(shí)例 */ sessionFactory = config.buildSessionFactory(); }catch(RuntimeException e){e.printStackTrace();throw e;} } /** 查詢所有的Customer對(duì)象,然后調(diào)用printCustomer()方法打印Customer對(duì)象信息 */ public void findAllCustomers(ServletContext context,PrintWriter out) throws Exception{ Session session = sessionFactory.openSession(); //創(chuàng)建一個(gè)會(huì)話 Transaction tx = null; try { tx = session.beginTransaction(); //開始一個(gè)事務(wù) Query query=session.createQuery("from Customer as c order by c.name asc"); List customers=query.list(); for (Iterator it = customers.iterator(); it.hasNext();) { printCustomer(context,out,(Customer) it.next()); } tx.commit(); //提交事務(wù) }catch (RuntimeException e) { if (tx != null) { tx.rollback(); } throw e; } finally { session.close(); } } /** 持久化一個(gè)Customer對(duì)象 */ public void saveCustomer(Customer customer){ Session session = sessionFactory.openSession(); Transaction tx = null; try { tx = session.beginTransaction(); session.save(customer); tx.commit(); }catch (RuntimeException e) { if (tx != null) { tx.rollback(); } throw e; } finally { session.close(); } } /** 按照OID加載一個(gè)Customer對(duì)象,然后修改它的屬性 */ public void loadAndUpdateCustomer(Long customer_id,String address){ Session session = sessionFactory.openSession(); Transaction tx = null; try { tx = session.beginTransaction(); Customer c=(Customer)session.get(Customer.class,customer_id); c.setAddress(address); tx.commit(); }catch (RuntimeException e) { if (tx != null) { tx.rollback(); } throw e; } finally { session.close(); } } /**刪除Customer對(duì)象 */ public void deleteCustomer(Customer customer){ Session session = sessionFactory.openSession(); Transaction tx = null; try { tx = session.beginTransaction(); session.delete(customer); tx.commit(); }catch (RuntimeException e) { if (tx != null) { tx.rollback(); } throw e; } finally { session.close(); } } /** 選擇向控制臺(tái)還是Web網(wǎng)頁輸出Customer對(duì)象的信息 */ private void printCustomer(ServletContext context,PrintWriter out,Customer customer)throws Exception{ if(context!=null) printCustomerInWeb(context,out,customer); else printCustomer( out,customer); } /** 把Customer對(duì)象的信息輸出到控制臺(tái),如DOS 控制臺(tái)*/ private void printCustomer(PrintWriter out,Customer customer)throws Exception{ byte[] buffer=customer.getImage(); FileOutputStream fout=new FileOutputStream("photo_copy.gif"); fout.write(buffer); fout.close(); out.println("------以下是"+customer.getName()+"的個(gè)人信息------"); out.println("ID: "+customer.getId()); out.println("口令: "+customer.getPassword()); out.println("E-Mail: "+customer.getEmail()); out.println("電話: "+customer.getPhone()); out.println("地址: "+customer.getAddress()); String sex=customer.getSex()=='M'? "男":"女"; out.println("性別: "+sex); String marriedStatus=customer.isMarried()? "已婚":"未婚"; out.println("婚姻狀況: "+marriedStatus); out.println("生日: "+customer.getBirthday()); out.println("注冊(cè)時(shí)間: "+customer.getRegisteredTime()); out.println("自我介紹: "+customer.getDescription()); } /** 把Customer對(duì)象的信息輸出到動(dòng)態(tài)網(wǎng)頁 */ private void printCustomerInWeb(ServletContext context,PrintWriter out,Customer customer)throws Exception{ //保存照片 byte[] buffer=customer.getImage(); String path=context.getRealPath("/"); FileOutputStream fout=new FileOutputStream(path+"photo_copy.gif"); fout.write(buffer); fout.close(); out.println("------以下是"+customer.getName()+"的個(gè)人信息------"+"<br>"); out.println("ID: "+customer.getId()+"<br>"); out.println("口令: "+customer.getPassword()+"<br>"); out.println("E-Mail: "+customer.getEmail()+"<br>"); out.println("電話: "+customer.getPhone()+"<br>"); out.println("地址: "+customer.getAddress()+"<br>"); String sex=customer.getSex()=='M'? "男":"女"; out.println("性別: "+sex+"<br>"); String marriedStatus=customer.isMarried()? "已婚":"未婚"; out.println("婚姻狀況: "+marriedStatus+"<br>"); out.println("生日: "+customer.getBirthday()+"<br>"); out.println("注冊(cè)時(shí)間: "+customer.getRegisteredTime()+"<br>"); out.println("自我介紹: "+customer.getDescription()+"<br>"); out.println("<img src='photo_copy.gif' border=0><p>"); } public void test(ServletContext context,PrintWriter out) throws Exception{ Customer customer=new Customer(); customer.setName("Tom"); customer.setEmail("tom@yahoo.com"); customer.setPassword("1234"); customer.setPhone(55556666); customer.setAddress("Shanghai"); customer.setSex('M'); customer.setDescription("I am very honest."); //設(shè)置Customer對(duì)象的image屬性,它是字節(jié)數(shù)組,存放photo.gif文件中的二進(jìn)制數(shù)據(jù) //photo.gif文件和BusinessService.class文件位于同一個(gè)目錄下 InputStream in=this.getClass().getResourceAsStream("photo.gif"); byte[] buffer = new byte[in.available()]; in.read(buffer); customer.setImage(buffer); //設(shè)置Customer對(duì)象的birthday屬性,它是java.sql.Date類型 customer.setBirthday(Date.valueOf("1980-05-06")); saveCustomer(customer); findAllCustomers(context,out); loadAndUpdateCustomer(customer.getId(),"Beijing"); findAllCustomers(context,out); deleteCustomer(customer); } public static void main(String args[]) throws Exception { new BusinessService().test(null,new PrintWriter(System.out,true)); sessionFactory.close(); } }
saveCustomer()方法
該方法調(diào)用Session的save()方法,把Customer對(duì)象持久化到數(shù)據(jù)庫中。
tx = session.beginTransaction(); session.save(customer); tx.commit();
當(dāng)運(yùn)行session.save()方法時(shí),Hibernate執(zhí)行以下SQL語句:
insert into CUSTOMERS (ID, NAME, EMAIL, PASSWORD, PHONE, ADDRESS, SEX, IS_MARRIED,DESCRIPTION, IMAGE, BIRTHDAY, REGISTERED_TIME) values(1,'Tom','tom@yahoo.com','1234',55556666,'Shanghai','M',0,'I am very honest.', ?,'1980-05-06',null)
在test()方法中并沒有設(shè)置Customer對(duì)象的id屬性,Hibernate會(huì)根據(jù)映射文件的配置,采用increment標(biāo)識(shí)符生成器自動(dòng)以遞增的方式為OID賦值。在Customer.hbm.xml文件中相關(guān)的映射代碼如下:
<id name="id" column="ID" type="long"> <generator class="increment"/> </id>
findAllCustomers()方法
該方法通過Query接口查詢所有的Customer對(duì)象。
tx = session.beginTransaction(); //開始一個(gè)事務(wù) Query query=session.createQuery("from Customer as c order by c.name asc"); List customers=query.list(); for (Iterator it = customers.iterator(); it.hasNext();) { printCustomer(context,out,(Customer) it.next()); } tx.commit(); //提交事務(wù)
Session的createQuery()方法的參數(shù)“from Customer as c order by c.name asc”使用的是Hibernate查詢語言。運(yùn)行Query.list()方法時(shí), Hibernate執(zhí)行以下SQL語句:
select * from CUSTOMERS order by NAME asc;
loadAndUpdateCustomer ()方法
該方法調(diào)用Session的get()方法,加載Customer對(duì)象,然后再修改Customer對(duì)象的屬性。
tx = session.beginTransaction(); Customer c=(Customer)session.get(Customer.class,customer_id); c.setAddress(address); //修改內(nèi)存中Customer對(duì)象的address屬性 tx.commit();
以上代碼先調(diào)用Session的get()方法,它按照參數(shù)指定的OID從數(shù)據(jù)庫中檢索出匹配的Customer對(duì)象,Hibernate會(huì)執(zhí)行以下SQL語句:
select * from CUSTOMERS where ID=1;
loadAndUpdateCustomer()方法接著修改Customer對(duì)象的address屬性。那么,Hibernate會(huì)不會(huì)同步更新數(shù)據(jù)庫中相應(yīng)的CUSTOMERS表的記錄呢?答案是肯定的。Hibernate采用臟檢查機(jī)制,按照內(nèi)存中的Customer對(duì)象的狀態(tài)的變化,來同步更新數(shù)據(jù)庫中相關(guān)的數(shù)據(jù),Hibernate會(huì)執(zhí)行以下SQL語句:
update CUSTOMERS set NAME="Tom",EMAIL="Tom@yahoo.com"…ADDRESS="Beijing"… where ID=1;
盡管只有Customer對(duì)象的address屬性發(fā)生了變化,但是Hibernate執(zhí)行的update語句中會(huì)包含所有的字段。
deleteCustomer()方法
該方法調(diào)用Session的delete()方法,刪除特定的Customer對(duì)象:
tx = session.beginTransaction(); session.delete(customer); tx.commit();
運(yùn)行session.delete()方法時(shí),Hibernate根據(jù)Customer對(duì)象的OID,執(zhí)行以下SQL delete語句:
delete from CUSTOMERS where ID=1;
八、效果圖
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