Hibernate第四天

Lazy:延迟加载。

Hibrnater:类型是去掉路径，首字母小写。比如

<property name="name" column="f_name" type="string"> 

 

注意的是Hibrnater的date日期和java的不一样 timestamp

小练习

 

一对一关联

 

首先PO类

 

package com.lovo.po;public class HusbandPO {private int id;private String name;private WifePO myWife;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 WifePO getMyWife() {return myWife;}public void setMyWife(WifePO myWife) {this.myWife = myWife;}} 

 

 

package com.lovo.po;public class WifePO {private int id;private String name;private HusbandPO myMan;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 HusbandPO getMyMan() {return myMan;}public void setMyMan(HusbandPO myMan) {this.myMan = myMan;}} 

 

再者POhbm.xml

 

 

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" ><hibernate-mapping><class name="com.lovo.po.HusbandPO" table="t_husband"><id name="id" column="f_id" type="int"><generator class="increment"></generator></id><property name="name" column="f_name" type="string"></property><one-to-one name="myWife" cascade="all" class="com.lovo.po.WifePO"></one-to-one></class></hibernate-mapping> 

 

 

<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE hibernate-mapping PUBLIC "-//Hibernate/Hibernate Mapping DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd" ><hibernate-mapping><class name="com.lovo.po.WifePO" table="t_wife"><id name="id" column="f_id" type="int"><generator class="foreign"><param name="property">myMan</param></generator></id><property name="name" column="f_name" type="string"></property><one-to-one name="myMan" class="com.lovo.po.HusbandPO"></one-to-one></class></hibernate-mapping> 

 

当然还要配置hibernate.cfg.xml

 

<mapping resource="com/lovo/po/HusbandPO.hbm.xml" /><mapping resource="com/lovo/po/WifePO.hbm.xml" /> 

 

持久类：

 

package com.lovo.dao;import java.util.Iterator;import java.util.List;import org.hibernate.Criteria;import org.hibernate.Hibernate;import org.hibernate.Query;import org.hibernate.Session;import org.hibernate.Transaction;import org.hibernate.criterion.Criterion;import org.hibernate.criterion.DetachedCriteria;import org.hibernate.criterion.Order;import org.hibernate.criterion.Restrictions;import com.lovo.db.HibernateSessionFactory;import com.lovo.po.HusbandPO;import com.lovo.po.UserPO;import com.lovo.po.WifePO;public class UserDAO {public void addUser(UserPO user){Session session = HibernateSessionFactory.getSession();Transaction transaction = session.beginTransaction();session.save(user);transaction.commit();session.close();}public void delUser(UserPO user){Session session = HibernateSessionFactory.getSession();Transaction transaction = session.beginTransaction();session.delete(user);transaction.commit();session.close();}public void modUser(UserPO user){Session session = HibernateSessionFactory.getSession();Transaction transaction = session.beginTransaction();session.update(user);transaction.commit();session.close();}public void getUserById(int id){Session session = HibernateSessionFactory.getSession();UserPO user = (UserPO)session.get(UserPO.class, id);//UserPO user = (UserPO)session.load(UserPO.class, id);System.out.println(user.getName() + " " + user.getPassword());session.close();}public void getAllUser(){Session session = HibernateSessionFactory.getSession();String hql = "select new UserPO(name,password) from UserPO where id = 1";//String sql = "select * from t_user";Query query = session.createQuery(hql);query.setMaxResults(10);query.setFirstResult(1);//Query query = session.createSQLQuery(sql);List allUsers = query.list();for(int i = 0; i < allUsers.size(); i++){//Object[] objs = (Object[])allUsers.get(i);//System.out.println(objs[1] + " " + objs[2]);UserPO user = (UserPO)allUsers.get(i);System.out.println(user.getName());//Object[] name = (Object[])allUsers.get(i);//System.out.println(name[1]);}//Iterator it = query.iterate();//while(it.hasNext()){//UserPO user = (UserPO)it.next();//String username = user.getName(); //System.out.println(username);//}session.close();}public void getUsers(UserPO user) {String hql = "from UserPO where name = :name and password = :password";Session session = HibernateSessionFactory.getSession();Query query = session.createQuery(hql);//query.setString("name", user.getName());//query.setString("password", user.getPassword());query.setParameter("name", user.getName());query.setParameter("password", user.getPassword());//query.setProperties(user);List l = query.list();System.out.println(l.size());session.close();}public void useCriteria(){Session session = HibernateSessionFactory.getSession();Criteria criteria = session.createCriteria(UserPO.class);//criteria.add(Restrictions.gt("id", 1));//criteria.add(Restrictions.eq("name","zbz"));//Criterion criterion = Restrictions.or(Restrictions.lt("id", 2), Restrictions.gt("id", 5));//criteria.add(Restrictions.and(criterion, Restrictions.like("name", "%c%")));//criteria.add(Restrictions.sqlRestriction("f_name = 'zbz'"));criteria.addOrder(Order.desc("id"));criteria.addOrder(Order.asc("name"));criteria.setFirstResult(1);criteria.setMaxResults(10);List allUsers = criteria.list();for(int i = 0; i < allUsers.size(); i++){UserPO user = (UserPO)allUsers.get(i);System.out.println(user.getName());}session.close();}public void useDetachedCriteria(DetachedCriteria dc){Session session = HibernateSessionFactory.getSession();Criteria criteria = dc.getExecutableCriteria(session);List allUsers = criteria.list();for(int i = 0; i < allUsers.size(); i++){UserPO user = (UserPO)allUsers.get(i);System.out.println(user.getName());}session.close();}public void marry(HusbandPO he,WifePO she){he.setMyWife(she);she.setMyMan(he);Session session = HibernateSessionFactory.getSession();Transaction transaction = session.beginTransaction();session.save(he);transaction.commit();session.close();}} 

 

 

package com.lovo.test;import org.hibernate.criterion.DetachedCriteria;import org.hibernate.criterion.Order;import org.hibernate.criterion.Restrictions;import com.lovo.dao.UserDAO;import com.lovo.po.HusbandPO;import com.lovo.po.UserPO;import com.lovo.po.WifePO;public class TestMain {/** * @param args */public static void main(String[] args) {// TODO Auto-generated method stubUserPO user = new UserPO();user.setName("zbz");user.setPassword("frjjno3");UserDAO dao = new UserDAO();//dao.delUser(user);//dao.getUserById(4);//dao.getUsers(user);//dao.useCriteria();//DetachedCriteria dc = DetachedCriteria.forClass(UserPO.class);//dc.add(Restrictions.ge("id", 2));//dc.addOrder(Order.asc("name"));//dao.useDetachedCriteria(dc);HusbandPO he = new HusbandPO();WifePO she = new WifePO();he.setName("ZG");she.setName("SS");dao.marry(he, she);}} 

 

 

PS:

 

如何将oracle中存放的图片(如Blob类类型的字段)还原成一副图片

 

 

 

在Oracle中，LOB（Large Object，大型对象）类型的字段现在用得越来越多了。因为这种类型的字段，容量大（最多能容纳4GB的数据），且一个表中可以有多个这种类型的字段，很灵活，适用于数据量非常大的业务领域（如图象、档案等）。而LONG、LONG RAW等类型的字段，虽然存储容量也不小（可达2GB），但由于一个表中只能有一个这样类型的字段的限制，现在已很少使用了。

LOB类型分为BLOB和CLOB两种：BLOB即二进制大型对象（Binary Large Object），适用于存贮非文本的字节流数据（如程序、图象、影音等）。而CLOB，即字符型大型对象（Character Large Object），则与字符集相关，适于存贮文本型的数据（如历史档案、大部头著作等）。

下面以程序实例说明通过JDBC操纵Oracle数据库LOB类型字段的几种情况。

1、往数据库中插入一个新的CLOB对象public static void clobInsert(String infile) throws Exception{/* 设定不自动提交 */boolean defaultCommit = conn.getAutoCommit();conn.setAutoCommit(false);try {/* 插入一个空的CLOB对象 */stmt.executeUpdate("INSERT INTO TEST_CLOB VALUES ('111', EMPTY_CLOB())");/* 查询此CLOB对象并锁定 */ResultSet rs = stmt.executeQuery("SELECT CLOBCOL FROM TEST_CLOB WHERE ID='111' FOR UPDATE");while (rs.next()) {/* 取出此CLOB对象 */oracle.sql.CLOB clob = (oracle.sql.CLOB)rs.getClob("CLOBCOL");/* 向CLOB对象中写入数据 */BufferedWriter out = new BufferedWriter(clob.getCharacterOutputStream());BufferedReader in = new BufferedReader(new FileReader(infile));int c;while ((c=in.read())!=-1) {out.write(c);}in.close();out.close();}/* 正式提交 */conn.commit();} catch (Exception ex) {/* 出错回滚 */conn.rollback();throw ex;}/* 恢复原提交状态 */conn.setAutoCommit(defaultCommit);}2、修改CLOB对象（是在原CLOB对象基础上进行覆盖式的修改）public static void clobModify(String infile) throws Exception{/* 设定不自动提交 */boolean defaultCommit = conn.getAutoCommit();conn.setAutoCommit(false);try {/* 查询CLOB对象并锁定 */ResultSet rs = stmt.executeQuery("SELECT CLOBCOL FROM TEST_CLOB WHERE ID='111' FOR UPDATE");while (rs.next()) {/* 获取此CLOB对象 */oracle.sql.CLOB clob = (oracle.sql.CLOB)rs.getClob("CLOBCOL");/* 进行覆盖式修改 */BufferedWriter out = new BufferedWriter(clob.getCharacterOutputStream());BufferedReader in = new BufferedReader(new FileReader(infile));int c;while ((c=in.read())!=-1) {out.write(c);}in.close();out.close();}/* 正式提交 */conn.commit();} catch (Exception ex) {/* 出错回滚 */conn.rollback();throw ex;}/* 恢复原提交状态 */conn.setAutoCommit(defaultCommit);}3、替换CLOB对象（将原CLOB对象清除，换成一个全新的CLOB对象）public static void clobReplace(String infile) throws Exception{/* 设定不自动提交 */boolean defaultCommit = conn.getAutoCommit();conn.setAutoCommit(false);try {/* 清空原CLOB对象 */stmt.executeUpdate("UPDATE TEST_CLOB SET CLOBCOL=EMPTY_CLOB() WHERE ID='111'");/* 查询CLOB对象并锁定 */ResultSet rs = stmt.executeQuery("SELECT CLOBCOL FROM TEST_CLOB WHERE ID='111' FOR UPDATE");while (rs.next()) {/* 获取此CLOB对象 */oracle.sql.CLOB clob = (oracle.sql.CLOB)rs.getClob("CLOBCOL");/* 更新数据 */BufferedWriter out = new BufferedWriter(clob.getCharacterOutputStream());BufferedReader in = new BufferedReader(new FileReader(infile));int c;while ((c=in.read())!=-1) {out.write(c);}in.close();out.close();}/* 正式提交 */conn.commit();} catch (Exception ex) {/* 出错回滚 */conn.rollback();throw ex;}/* 恢复原提交状态 */conn.setAutoCommit(defaultCommit);}4、CLOB对象读取public static void clobRead(String outfile) throws Exception{/* 设定不自动提交 */boolean defaultCommit = conn.getAutoCommit();conn.setAutoCommit(false);try {/* 查询CLOB对象 */ResultSet rs = stmt.executeQuery("SELECT * FROM TEST_CLOB WHERE ID='111'");while (rs.next()) {/* 获取CLOB对象 */oracle.sql.CLOB clob = (oracle.sql.CLOB)rs.getClob("CLOBCOL");/* 以字符形式输出 */BufferedReader in = new BufferedReader(clob.getCharacterStream());BufferedWriter out = new BufferedWriter(new FileWriter(outfile));int c;while ((c=in.read())!=-1) {out.write(c);}out.close();in.close();}} catch (Exception ex) {conn.rollback();throw ex;}/* 恢复原提交状态 */conn.setAutoCommit(defaultCommit);}二、 BLOB对象的存取1、 向数据库中插入一个新的BLOB对象public static void blobInsert(String infile) throws Exception{/* 设定不自动提交 */boolean defaultCommit = conn.getAutoCommit();conn.setAutoCommit(false);try {/* 插入一个空的BLOB对象 */stmt.executeUpdate("INSERT INTO TEST_BLOB VALUES ('222', EMPTY_BLOB())");/* 查询此BLOB对象并锁定 */ResultSet rs = stmt.executeQuery("SELECT BLOBCOL FROM TEST_BLOB WHERE ID='222' FOR UPDATE");while (rs.next()) {/* 取出此BLOB对象 */oracle.sql.BLOB blob = (oracle.sql.BLOB)rs.getBlob("BLOBCOL");/* 向BLOB对象中写入数据 */BufferedOutputStream out = new BufferedOutputStream(blob.getBinaryOutputStream());BufferedInputStream in = new BufferedInputStream(new FileInputStream(infile));int c;while ((c=in.read())!=-1) {out.write(c);}in.close();out.close();}/* 正式提交 */conn.commit();} catch (Exception ex) {/* 出错回滚 */conn.rollback();throw ex;}/* 恢复原提交状态 */conn.setAutoCommit(defaultCommit);}2、修改BLOB对象（是在原BLOB对象基础上进行覆盖式的修改）public static void blobModify(String infile) throws Exception{/* 设定不自动提交 */boolean defaultCommit = conn.getAutoCommit();conn.setAutoCommit(false);try {/* 查询BLOB对象并锁定 */ResultSet rs = stmt.executeQuery("SELECT BLOBCOL FROM TEST_BLOB WHERE ID='222' FOR UPDATE");while (rs.next()) {/* 取出此BLOB对象 */oracle.sql.BLOB blob = (oracle.sql.BLOB)rs.getBlob("BLOBCOL");/* 向BLOB对象中写入数据 */BufferedOutputStream out = new BufferedOutputStream(blob.getBinaryOutputStream());BufferedInputStream in = new BufferedInputStream(new FileInputStream(infile));int c;while ((c=in.read())!=-1) {out.write(c);}in.close();out.close();}/* 正式提交 */conn.commit();} catch (Exception ex) {/* 出错回滚 */conn.rollback();throw ex;}/* 恢复原提交状态 */conn.setAutoCommit(defaultCommit);}3、替换BLOB对象（将原BLOB对象清除，换成一个全新的BLOB对象）public static void blobReplace(String infile) throws Exception{/* 设定不自动提交 */boolean defaultCommit = conn.getAutoCommit();conn.setAutoCommit(false);try {/* 清空原BLOB对象 */stmt.executeUpdate("UPDATE TEST_BLOB SET BLOBCOL=EMPTY_BLOB() WHERE ID='222'");/* 查询此BLOB对象并锁定 */ResultSet rs = stmt.executeQuery("SELECT BLOBCOL FROM TEST_BLOB WHERE ID='222' FOR UPDATE");while (rs.next()) {/* 取出此BLOB对象 */oracle.sql.BLOB blob = (oracle.sql.BLOB)rs.getBlob("BLOBCOL");/* 向BLOB对象中写入数据 */BufferedOutputStream out = new BufferedOutputStream(blob.getBinaryOutputStream());BufferedInputStream in = new BufferedInputStream(new FileInputStream(infile));int c;while ((c=in.read())!=-1) {out.write(c);}in.close();out.close();}/* 正式提交 */conn.commit();} catch (Exception ex) {/* 出错回滚 */conn.rollback();throw ex;}/* 恢复原提交状态 */conn.setAutoCommit(defaultCommit);}4、BLOB对象读取public static void blobRead(String outfile) throws Exception{/* 设定不自动提交 */boolean defaultCommit = conn.getAutoCommit();conn.setAutoCommit(false);try {/* 查询BLOB对象 */ResultSet rs = stmt.executeQuery("SELECT BLOBCOL FROM TEST_BLOB WHERE ID='222'");while (rs.next()) {/* 取出此BLOB对象 */oracle.sql.BLOB blob = (oracle.sql.BLOB)rs.getBlob("BLOBCOL");/* 以二进制形式输出 */BufferedOutputStream out = new BufferedOutputStream(new FileOutputStream(outfile));BufferedInputStream in = new BufferedInputStream(blob.getBinaryStream());int c;while ((c=in.read())!=-1) {out.write(c);}in.close();out.close();}/* 正式提交 */conn.commit();} catch (Exception ex) {/* 出错回滚 */conn.rollback();throw ex;}/* 恢复原提交状态 */conn.setAutoCommit(defaultCommit);} 

 

二是插入方式不同。

LOB数据不能象其它类型数据一样直接插入（INSERT）。插入前必须先插入一个空的LOB对象，CLOB类型的空对象为EMPTY_CLOB()，BLOB类型的空对象为EMPTY_BLOB()。之后通过SELECT命令查询得到先前插入的记录并锁定，继而将空对象修改为所要插入的LOB对象。

三是修改方式不同。

其它类型的字段修改时，用UPDATE … SET…命令即可。而LOB类型字段，则只能用SELECT … FOR UPDATE命令将记录查询出来并锁定，然后才能修改。且修改也有两种改法：一是在原数据基础上的修改（即覆盖式修改），执行SELECT … FOR UPDATE后再改数据；二是替换（先将原数据清掉，再修改），先执行UPDATE命令将LOB字段之值设为空的LOB对象，然后进行第一种改法。建议使用替换的方法，以实现与其它字段UPDATE操作后一样的效果。

四是存取时应使用由数据库JDBC驱动程序提供的LOB操作类。

对于Oracle数据库，应使用oracle.sql.CLOB和oracle.sql.BLOB。不使用由数据库JDBC驱动程序提供的LOB类时，程序运行时易于出现“抽象方法调用”的错误，这是因为JDBC所定义的java.sql.Clob与java.sql.Blob接口，其中的一些方法并未在数据库厂家提供的驱动程序中真正实现。

五是存取手段与文件操作相仿。

对于BLOB类型，应用InputStream/OutputStream类，此类不进行编码转换，逐个字节存取。oracle.sql.BLOB类相应提供了getBinaryStream()和getBinaryOutputStream()两个方法，前一个方法用于读取Oracle的BLOB字段，后一个方法用于将数据写入Oracle的BLOB字段。

对于CLOB类型，应用Reader/Writer类，此类进行编码转换。oracle.sql.CLOB类相应提供了getCharacterStream()和getCharacterOutputStream()两个方法，前一个方法用于读取Oracle的CLOB字段，后一个方法用于将数据写入Oracle的CLOB字段。

需要说明的是，为了大幅提高程序执行效率，对BLOB/CLOB字段的读写操作，应该使用缓冲操作类（带Buffered前缀），即：BufferedInputStream，BufferedOutputStream，BufferedReader，BufferedWriter。例程中全部使用了缓冲操作类。