初學Hibernate心得/
阿新 • • 發佈：2018-03-27
nfa 分享圖片 記錄 使用 利用 {} 所有 item 語句
看了幾天的心得記錄一下
1、配置hibernate
1 <?xml version="1.0" encoding="UTF-8"?> 2 <!DOCTYPE hibernate-configuration PUBLIC 3 "-//Hibernate/Hibernate Configuration DTD 3.0//EN" 4 "http://www.hibernate.org/dtd/hibernate-configuration-3.0.dtd"> 5 <!--Hibernate的配置信息 --> 6 <hibernate-configuration> 7 <!--配置工廠信息，全局信息 --> 8 <session-factory> 9 <!--1、設置四本一言 --> 10 <!--四本一言 四大基本項： 1、驅動類名 2、指明需要連接的url 3、用戶名 4、密碼 Hibernate支持不同的數據庫，但是每種數據庫語法可能有區別，可以使用方言,註意版本 --> 11 <!--數據庫驅動類全稱 --> 12 <property name="hibernate.connection.driver_class">com.mysql.jdbc.Driver</property> 13 <!--數據庫url地址 --> 14 <property name="hibernate.connection.url">jdbc:mysql://localhost:3306/text?characterEncoding=UTF-8</property> 15 <!--用戶名 --> 16 <property name="hibernate.connection.username">root</property> 17 <!--密碼 --> 18 <property name="hibernate.connection.password">1111</property> 19 <!--方言 --> 20 <property name="hibernate.dialect">org.hibernate.dialect.MySQL5Dialect</property> 21 <!--2、全局配置信息 --> 22 <!--執行DDL的類別： 23 create:每次都刪除新建 24 update:存在就修改，不存在就新建 --> 25 <property name="hibernate.hbm2ddl.auto">update</property> 26 <!--是否顯示SQL語句 --> 27 <property name="hibernate.show_sql">true</property> 28 <!--是否格式化SQL語句 --> 29 <property name="hibernate.format_sql">true</property> 30 <!-- 啟用getCurrentSession，默認未啟用 --> 31 <property name="hibernate.current_session_context_class">thread</property> 32 <!--3、加載配置文件 --> 33 <mapping resource="com/Student.hbm.xml"></mapping> 34 <mapping resource="com/Classes.hbm.xml"></mapping> 35 36 </session-factory> 37 </hibernate-configuration>
2、建立實體類
課程類
1 package com; 2 3 import java.util.HashSet; 4 import java.util.Set; 5 6 public class Classes { 7 /** 8 * @param cid 9 * @param name 10 */ 11 public Classes() {} 12 public Classes(int cid, String name) { 13 this.cid = cid; 14 this.name = name; 15 } 16 private int cid; //標示符屬性 17 private String name; //一般屬性 18 private String description; 19 private Set<Student> student = new HashSet<Student>(); 20 public Set<Student> getStudent() { 21 return student; 22 } 23 public void setStudent(Set<Student> student) { 24 this.student = student; 25 } 26 27 public int getCid() { 28 return cid; 29 } 30 public void setCid(int cid) { 31 this.cid = cid; 32 } 33 public String getName() { 34 return name; 35 } 36 public void setName(String name) { 37 this.name = name; 38 } 39 public String getDescription() { 40 return description; 41 } 42 public void setDescription(String description) { 43 this.description = description; 44 } 45 46 }
學生類
1 package com; 2 3 public class Student { 4 public Student(int sid, String name, String description, Classes classes) { 5 this.sid = sid; 6 this.name = name; 7 this.description = description; 8 this.classes = classes; 9 } 10 public Student(int sid, String name, Classes classes) { 11 this.sid = sid; 12 this.name = name; 13 this.classes = classes; 14 } 15 public Student() 16 {} 17 private int sid; 18 private String name; 19 private String description; 20 private Classes classes; 21 public Classes getClasses() { 22 return classes; 23 } 24 public void setClasses(Classes classes) { 25 this.classes = classes; 26 } 27 28 public int getSid() { 29 return sid; 30 } 31 public void setSid(int sid) { 32 this.sid = sid; 33 } 34 public String getName() { 35 return name; 36 } 37 public void setName(String name) { 38 this.name = name; 39 } 40 public String getDescription() { 41 return description; 42 } 43 public void setDescription(String description) { 44 this.description = description; 45 } 46 47 }
3、配置實例類
<?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> <!-- name：實體, table:表名 --> <class name="com.Classes" table="m2o_cla"> <!-- name:主鍵的名字,column:主鍵數據庫表列,identity自增 --> <id name="cid"> <!-- Hibernate使用generator類來生成主鍵 --> <generator class="identity" /> </id> <!-- name：實體中的屬性名，length:長度 ,column:表中的字段(實體屬性和字段一致可省略)，type:類型(可不寫由hiberbate自動匹配) --> <property name="name" /> <property name="description"/> <!-- inverse:這個屬性（stus） 是否為關系的維護方，默認值為false 如果inverse設置為true，表示將由對方維護兩者之間的關聯關系 --> <!--cascade（級聯）意思是指定兩個對象之間的操作聯動關系，對一個對象執行了操作之後，對其指定的級聯對象也需要執行相同的操作 all-代表在所有的情況下都執行級聯操作 none-在所有情況下都不執行級聯操作 save-update-在保存和更新的時候執行級聯操作 delete-在刪除的時候執行級聯操作 --> <!--lazy:延遲加載，默認true,如學生實體不調用班級實體信息，可以不用加載 --> <set name="student" inverse="false" cascade="all" lazy="true"> <!-- 關系維護方的外鍵列 --> <key column="cid"></key> <one-to-many class="com.Student" /> </set> </class> </hibernate-mapping>
<?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> <!-- name：實體, table:表名 --> <class name="com.Student" table="m2o_stu"> <!-- name:主鍵的名字,column:主鍵數據庫表列,identity自增 --> <id name="sid"> <!-- Hibernate使用generator類來生成主鍵 --> <generator class="identity" /> </id> <!-- name：實體中的屬性名，length:長度 ,column:表中的字段(實體屬性和字段一致可省略)，type:類型(可不寫由hiberbate自動匹配) --> <property name="name" /> <property name="description"/> <!-- 對應班級配置中的cid --> <many-to-one name="classes" column="cid" cascade="save-update"></many-to-one> </class> </hibernate-mapping>
4、幫助類，因Configuration中運行會生成大量sql語句，用static限定/
1 package com; 2 import org.hibernate.Session; 3 import org.hibernate.SessionFactory; 4 import org.hibernate.Transaction; 5 import org.hibernate.cfg.Configuration; 6 7 public class project_text { 8 public static Configuration cfg; 9 public static SessionFactory sessionFactory; 10 static { 11 cfg = new Configuration().configure("hibernate.cfg.xml"); 12 sessionFactory = cfg.buildSessionFactory(); 13 } 14 public static Session openSesson() 15 { 16 return sessionFactory.openSession(); 17 } 18 public static Transaction beginTransaction(Session session) 19 { 20 return session.beginTransaction(); 21 } 22 }
5、通過對實體類的操作實現對數據庫的操作/
沒copy出text實體類/原理同上/
1 package com; 2 3 import java.util.List; 4 5 import org.hibernate.Query; 6 import org.hibernate.Session; 7 import org.hibernate.SessionFactory; 8 import org.hibernate.Transaction; 9 import org.hibernate.cfg.Configuration; 10 public class pro_text { 11 12 public static void main(String[] args) { 13 project_text text_hibernate = new project_text(); 14 Session textSession = text_hibernate.openSesson(); 15 Transaction textTransaction = text_hibernate.beginTransaction(textSession); 16 text text1 =new text(2,"quanmina","123"); 17 job job1 =new job(2,"adress","1111"); 18 19 textSession.save(text1); 20 21 text text2 = new text(); 22 text2.setId(1); 23 text2.setName("updatename"); 24 text2.setPassword("123123"); 25 textSession.update(text2); 26 27 // text text3 = new text(); 28 // text3.setId(3); 29 // textSession.delete("3",text3); 30 31 //text text4 = (text)textSession.get("text", 1); 32 //System.out.println("id:"+text4.getId()+"---name:"+text4.getName()+"----password:"+text4.getPassword()); 33 Query query = textSession.createQuery("from text"); 34 List<text> textList = query.list(); 35 System.out.println("-*----------------------------------------*-"); 36 for( text item : textList) 37 { 38 System.out.println("id:"+item.getId()+"---name:"+item.getName()+"----password:"+item.getPassword()+"------"+item.get_job().getJobAdress()); 39 } 40 41 Query query1 = textSession.createQuery("from text,job where text.id=job.id"); 42 List<text> textList1 = query1.list(); 43 System.out.println("-*----------------------------------------*-"); 44 for( text item : textList1) 45 { 46 System.out.println("id:"+item.getId()+"---name:"+item.getName()+"----password:"+item.getPassword()); 47 } 48 textSession.getTransaction().commit(); 49 textSession.close(); 50 51 // TODO 自動生成的方法存根 52 // Configuration conf=new Configuration();//這個構造方法調用了一個受保護的構造方法： 53 // conf.configure("hibernate.cfg.xml"); 54 // //創建工廠 55 // SessionFactory sf=conf.buildSessionFactory(); 56 // //取得session 57 // Session session=sf.openSession(); 58 // //開始事務 59 // session.beginTransaction(); 60 // text text=new text(1,"quanmina","123"); 61 // session.save(text); 62 // System.out.println("保存成功"); 63 // session.getTransaction().commit(); 64 // session.close(); 65 // sf.close(); 66 } 67 68 }
6、mian函數，聯合查詢，一對多的例子/
1 package com; 2 3 import java.util.LinkedList; 4 import java.util.List; 5 6 import org.hibernate.Query; 7 import org.hibernate.Session; 8 import org.hibernate.Transaction; 9 10 public class StudClassesMian { 11 12 public static void main(String[] args) { 13 // TODO 自動生成的方法存根 14 project_text text_hibernate = new project_text(); 15 Session session = text_hibernate.openSesson(); 16 Transaction transaction = text_hibernate.beginTransaction(session); 17 Student student = new Student(); 18 student.setName("asfd"); 19 Classes classes = new Classes(); 20 classes.setName("12期"); 21 //創建班級與學生之間的關聯 22 student.setClasses(classes); //通過學生建立的關聯 23 //session.save(student); 24 transaction.commit(); 25 String hqlS= "select s.sid,s.name,c.cid,c.name from com.Student as s,com. Classes as c where s.classes = c.cid"; 26 Query query = session.createQuery(hqlS); 27 List<Object> list_stu = query.list(); 28 List<Student> listResult= new LinkedList<Student>(); 29 for(int i=0;i<list_stu.size();i++) 30 { 31 Object[] obj = (Object[])list_stu.get(i); 32 Classes cls = new Classes((int)obj[2],obj[3].toString()); //利用構造函數將查詢結構保存到實體類中，方便數據使用/ 33 Student stu = new Student((int)obj[0],obj[1].toString(),cls); 34 listResult.add(stu); 35 } 36 for(Student item : listResult) 37 { 38 System.out.println(item.getSid()+"=="+item.getName()+"=="+item.getClasses().getCid()+"=="+item.getClasses().getName()); 39 } 40 List<Object> list = query.list(); 41 for(int i=0;i<list.size();i++) 42 { 43 Object[] obj = (Object[])list.get(i); 44 System.out.println(obj[0]+"==="+obj[1]+"==="+obj[2]+"==="+obj[3]+"==="); 45 } 46 System. out.println(list.size()); 47 String SQLStr= "select s.sid as sid,s.name as sname,c.cid as cid,c.name as cname from m2o_stu as s, m2o_cla as c where s.cid = c.cid"; 48 Query querySQL = session.createSQLQuery(SQLStr); 49 List lsitSQL = querySQL.list(); 50 System. out.println(lsitSQL.size()); 51 session.close(); 52 } 53 54 }
初學Hibernate心得/